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diff --git a/old/52344-0.txt b/old/52344-0.txt deleted file mode 100644 index 79faa43..0000000 --- a/old/52344-0.txt +++ /dev/null @@ -1,10362 +0,0 @@ -The Project Gutenberg EBook of Science and Culture, and Other Essays, by -Thomas Henry Huxley - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Science and Culture, and Other Essays - -Author: Thomas Henry Huxley - -Release Date: June 15, 2016 [EBook #52344] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK SCIENCE AND CULTURE, OTHER ESSAYS *** - - - - -Produced by MWS, Adrian Mastronardi, Jason Palmer, Turgut -Dincer and the Online Distributed Proofreading Team at -http://www.pgdp.net (This file was produced from images -generously made available by The Internet Archive/American -Libraries.) - - - - - - - - SCIENCE AND CULTURE - - AND - - OTHER ESSAYS - -[Illustration] - - SCIENCE AND CULTURE - - AND - - OTHER ESSAYS - - BY - - THOMAS HENRY HUXLEY, LL.D., F.R.S. - - - London - MACMILLAN AND CO. - AND NEW YORK - 1888 - - _All rights reserved_ - - - _First Edition printed 1881 - Reprinted 1882, 1888._ - - - - -PREFACE. - - -The Addresses, Lectures, and Essays gathered together in this volume -have appeared at intervals during the past seven years, and I can give -no better reason for republishing them in their present form, than -the fact that three earlier collections of a similar nature have been -received with favour, and, indeed, have not yet ceased to be in request. - -I beg leave to offer my best thanks to the Editors and Publishers of -the various publications in which these pieces have appeared, for their -kindly accorded permission to reprint them. - - LONDON. _October 1881._ - - - - -CONTENTS. - - - I. - - SCIENCE AND CULTURE. - - An Address delivered at the Opening of Sir Josiah Mason’s - Science College, at Birmingham, on the 1st of October - 1880 Pages 1 to 23 - - - II. - - UNIVERSITIES: ACTUAL AND IDEAL. - - The Inaugural Address of the Lord Rector of the - University of Aberdeen, 27th February 1874.—_Contemporary - Review_, 1874 24 to 64 - - - III. - - TECHNICAL EDUCATION. - - An Address delivered to the Working Men’s Club and - Institute, 1st December 1877.—_Nineteenth Century_, 1878 65 to 85 - - - IV. - - ELEMENTARY INSTRUCTION IN PHYSIOLOGY. - - Read at the Meeting of the Domestic Economy Congress at - Birmingham, 1877 86 to 93 - - - V. - - JOSEPH PRIESTLEY. - - An Address delivered on the occasion of the Presentation - of a Statue of Priestley to the Town of Birmingham, on - the 1st of August 1874.—_Macmillan’s Magazine_, 1874 94 to 127 - - - VI. - - ON THE METHOD OF ZADIG. - - A Lecture delivered at the Working Men’s College, Great - Ormond Street, 1880.—_Nineteenth Century_, 1880 128 to 148 - - - VII. - - ON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE - VEGETABLE KINGDOMS. - - An Evening Lecture at the Royal Institution, Friday, - January 28, 1876.—_Macmillan’s Magazine_, 1874 149 to 179 - - - VIII. - - ON CERTAIN ERRORS RESPECTING THE STRUCTURE OF THE HEART - ATTRIBUTED TO ARISTOTLE. - - _Nature_, 6th November 1879 180 to 198 - - - IX. - - ON THE HYPOTHESIS THAT ANIMALS ARE AUTOMATA, AND ITS - HISTORY. - - An Address delivered at the Meeting of the British - Association for the Advancement of Science, at Belfast, - 1874.—_Fortnightly Review_, 1874 199 to 245 - - - X. - - ON SENSATION AND THE UNITY OF STRUCTURE OF THE - SENSIFEROUS ORGANS. - - An Evening Lecture at the Royal Institution, Friday, - March 7, 1879.—_Nineteenth Century_, 1879 246 to 273 - - - XI. - - EVOLUTION IN BIOLOGY. - - The _Encyclopædia Britannica_, Ninth Edition, vol. viii. - 1878 274 to 309 - - - XII. - - THE COMING OF AGE OF “THE ORIGIN OF SPECIES.” - - An evening Lecture at the Royal Institution, Friday, 9th - April 1880.—_Nature_, 1880 310 to 324 - - - XIII. - - THE CONNECTION OF THE BIOLOGICAL SCIENCES WITH MEDICINE. - - An Address delivered at the Meeting of the International - Medical Congress in London, 9th August 1881 325 to 349 - - - - -I. - -SCIENCE AND CULTURE. - - -Six years ago, as some of my present hearers may remember, I had the -privilege of addressing a large assemblage of the inhabitants of this -city, who had gathered together to do honour to the memory of their -famous townsman, Joseph Priestley;[1] and, if any satisfaction attaches -to posthumous glory, we may hope that the manes of the burnt-out -philosopher were then finally appeased. - -No man, however, who is endowed with a fair share of common sense, and -not more than a fair share of vanity, will identify either contemporary -or posthumous fame with the highest good; and Priestley’s life leaves -no doubt that he, at any rate, set a much higher value upon the -advancement of knowledge, and the promotion of that freedom of thought -which is at once the cause and the consequence of intellectual progress. - -Hence I am disposed to think that, if Priestley could be amongst us -to-day, the occasion of our meeting would afford him even greater -pleasure than the proceedings which celebrated the centenary of his -chief discovery. The kindly heart would be moved, the high sense -of social duty would be satisfied, by the spectacle of well-earned -wealth, neither squandered in tawdry luxury and vainglorious show, -nor scattered with the careless charity which blesses neither him -that gives nor him that takes, but expended in the execution of a -well-considered plan for the aid of present and future generations of -those who are willing to help themselves. - -We shall all be of one mind thus far. But it is needful to share -Priestley’s keen interest in physical science; and to have learned, as -he had learned, the value of scientific training in fields of inquiry -apparently far remote from physical science; in order to appreciate, as -he would have appreciated, the value of the noble gift which Sir Josiah -Mason has bestowed upon the inhabitants of the Midland district. - -For us children of the nineteenth century, however, the establishment -of a college under the conditions of Sir Josiah Mason’s Trust, has a -significance apart from any which it could have possessed a hundred -years ago. It appears to be an indication that we are reaching the -crisis of the battle, or rather of the long series of battles, which -have been fought over education in a campaign which began long before -Priestley’s time, and will probably not be finished just yet. - -In the last century, the combatants were the champions of ancient -literature, on the one side, and those of modern literature on the -other; but, some thirty years[2] ago, the contest became complicated by -the appearance of a third army, ranged round the banner of Physical -Science. - -I am not aware that any one has authority to speak in the name of this -new host. For it must be admitted to be somewhat of a guerilla force, -composed largely of irregulars, each of whom fights pretty much for -his own hand. But the impressions of a full private, who has seen a -good deal of service in the ranks, respecting the present position of -affairs and the conditions of a permanent peace, may not be devoid -of interest; and I do not know that I could make a better use of the -present opportunity than by laying them before you. - - -From the time that the first suggestion to introduce physical science -into ordinary education was timidly whispered, until now, the advocates -of scientific education have met with opposition of two kinds. On the -one hand, they have been pooh-poohed by the men of business who pride -themselves on being the representatives of practicality; while, on the -other hand, they have been excommunicated by the classical scholars, -in their capacity of Levites in charge of the ark of culture and -monopolists of liberal education. - -The practical men believed that the idol whom they worship—rule of -thumb—has been the source of the past prosperity, and will suffice -for the future welfare of the arts and manufactures. They were of -opinion that science is speculative rubbish; that theory and practice -have nothing to do with one another; and that the scientific habit of -mind is an impediment, rather than an aid, in the conduct of ordinary -affairs. - -I have used the past tense in speaking of the practical men—for -although they were very formidable thirty years ago, I am not sure -that the pure species has not been extirpated. In fact, so far as mere -argument goes, they have been subjected to such a _feu d’enfer_ that it -is a miracle if any have escaped. But I have remarked that your typical -practical man has an unexpected resemblance to one of Milton’s angels. -His spiritual wounds, such as are inflicted by logical weapons, may be -as deep as a well and as wide as a church door, but beyond shedding a -few drops of ichor, celestial or otherwise, he is no whit the worse. -So, if any of these opponents be left, I will not waste time in vain -repetition of the demonstrative evidence of the practical value of -science; but knowing that a parable will sometimes penetrate where -syllogisms fail to effect an entrance, I will offer a story for their -consideration. - -Once upon a time, a boy, with nothing to depend upon but his own -vigorous nature, was thrown into the thick of the struggle for -existence in the midst of a great manufacturing population. He seems -to have had a hard fight, inasmuch as, by the time he was thirty -years of age, his total disposable funds amounted to twenty pounds. -Nevertheless, middle life found him giving proof of his comprehension -of the practical problems he had been roughly called upon to solve, by -a career of remarkable prosperity. - -Finally, having reached old age with its well-earned surroundings of -“honour, troops of friends,” the hero of my story bethought himself of -those who were making a like start in life, and how he could stretch -out a helping hand to them. - -After long and anxious reflection this successful practical man -of business could devise nothing better than to provide them with -the means of obtaining “sound, extensive, and practical scientific -knowledge.” And he devoted a large part of his wealth and five years of -incessant work to this end. - -I need not point the moral of a tale which, as the solid and spacious -fabric of the Scientific College assures us, is no fable, nor can -anything which I could say intensify the force of this practical answer -to practical objections. - - -We may take it for granted then, that, in the opinion of those best -qualified to judge, the diffusion of thorough scientific education is -an absolutely essential condition of industrial progress; and that the -College which has been opened to-day will confer an inestimable boon -upon those whose livelihood is to be gained by the practice of the arts -and manufactures of the district. - -The only question worth discussion is, whether the conditions, under -which the work of the College is to be carried out, are such as to give -it the best possible chance of achieving permanent success. - -Sir Josiah Mason, without doubt most wisely, has left very large -freedom of action to the trustees, to whom he proposes ultimately to -commit the administration of the College, so that they may be able to -adjust its arrangements in accordance with the changing conditions -of the future. But, with respect to three points, he has laid most -explicit injunctions upon both administrators and teachers. - -Party politics are forbidden to enter into the minds of either, so -far as the work of the College is concerned; theology is as sternly -banished from its precincts; and finally, it is especially declared -that the College shall make no provision for “mere literary instruction -and education.” - -It does not concern me at present to dwell upon the first two -injunctions any longer than may be needful to express my full -conviction of their wisdom. But the third prohibition brings us face to -face with those other opponents of scientific education, who are by no -means in the moribund condition of the practical man, but alive, alert, -and formidable. - -It is not impossible that we shall hear this express exclusion -of “literary instruction and education” from a College which, -nevertheless, professes to give a high and efficient education, sharply -criticised. Certainly the time was that the Levites of culture would -have sounded their trumpets against its walls as against an educational -Jericho. - -How often have we not been told that the study of physical science -is incompetent to confer culture; that it touches none of the higher -problems of life; and, what is worse, that the continual devotion to -scientific studies tends to generate a narrow and bigoted belief in -the applicability of scientific methods to the search after truth of -all kinds. How frequently one has reason to observe that no reply to -a troublesome argument tells so well as calling its author a “mere -scientific specialist.” And, as I am afraid it is not permissible to -speak of this form of opposition to scientific education in the past -tense; may we not expect to be told that this, not only omission, but -prohibition, of “mere literary instruction and education” is a patent -example of scientific narrow-mindedness? - -I am not acquainted with Sir Josiah Mason’s reasons for the action -which he has taken; but if, as I apprehend is the case, he refers to -the ordinary classical course of our schools and universities by the -name of “mere literary instruction and education,” I venture to offer -sundry reasons of my own in support of that action. - -For I hold very strongly by two convictions—The first is, that neither -the discipline nor the subject-matter of classical education is of -such direct value to the student of physical science as to justify -the expenditure of valuable time upon either; and the second is, that -for the purpose of attaining real culture, an exclusively scientific -education is at least as effectual as an exclusively literary education. - -I need hardly point out to you that these opinions, especially the -latter, are diametrically opposed to those of the great majority of -educated Englishmen, influenced as they are by school and university -traditions. In their belief, culture is obtainable only by a liberal -education; and a liberal education is synonymous, not merely with -education and instruction in literature, but in one particular form of -literature, namely, that of Greek and Roman antiquity. They hold that -the man who has learned Latin and Greek, however little, is educated; -while he who is versed in other branches of knowledge, however deeply, -is a more or less respectable specialist, not admissible into the -cultured caste. The stamp of the educated man, the University degree, -is not for him. - -I am too well acquainted with the generous catholicity of spirit, the -true sympathy with scientific thought, which pervades the writings -of our chief apostle of culture to identify him with these opinions; -and yet one may cull from one and another of those epistles to the -Philistines, which so much delight all who do not answer to that name, -sentences which lend them some support. - -Mr. Arnold tells us that the meaning of culture is “to know the best -that has been thought and said in the world.” It is the criticism of -life contained in literature. That criticism regards “Europe as being, -for intellectual and spiritual purposes, one great confederation, bound -to a joint action and working to a common result; and whose members -have, for their common outfit, a knowledge of Greek, Roman, and Eastern -antiquity, and of one another. Special, local, and temporary advantages -being put out of account, that modern nation will in the intellectual -and spiritual sphere make most progress, which most thoroughly carries -out this programme. And what is that but saying that we too, all of us, -as individuals, the more thoroughly we carry it out, shall make the -more progress?”[3] - -We have here to deal with two distinct propositions. The first, that -a criticism of life is the essence of culture; the second, that -literature contains the materials which suffice for the construction of -such a criticism. - -I think that we must all assent to the first proposition. For -culture certainly means something quite different from learning or -technical skill. It implies the possession of an ideal, and the habit -of critically estimating the value of things by comparison with a -theoretic standard. Perfect culture should supply a complete theory of -life, based upon a clear knowledge alike of its possibilities and of -its limitations. - -But we may agree to all this, and yet strongly dissent from the -assumption that literature alone is competent to supply this knowledge. -After having learnt all that Greek, Roman, and Eastern antiquity have -thought and said, and all that modern literatures have to tell us, it -is not self-evident that we have laid a sufficiently broad and deep -foundation for that criticism of life which constitutes culture. - -Indeed, to any one acquainted with the scope of physical science, it is -not at all evident. Considering progress only in the “intellectual and -spiritual sphere,” I find myself wholly unable to admit that either -nations or individuals will really advance, if their common outfit -draws nothing from the stores of physical science. I should say that -an army, without weapons of precision and with no particular base of -operations, might more hopefully enter upon a campaign on the Rhine, -than a man, devoid of a knowledge of what physical science has done in -the last century, upon a criticism of life. - - -When a biologist meets with an anomaly, he instinctively turns to the -study of development to clear it up. The rationale of contradictory -opinions may with equal confidence be sought in history. - -It is, happily, no new thing that Englishmen should employ their wealth -in building and endowing institutions for educational purposes. But, -five or six hundred years ago, deeds of foundation expressed or implied -conditions as nearly as possible contrary to those which have been -thought expedient by Sir Josiah Mason. That is to say, physical science -was practically ignored, while a certain literary training was enjoined -as a means to the acquirement of knowledge which was essentially -theological. - -The reason of this singular contradiction between the actions of men -alike animated by a strong and disinterested desire to promote the -welfare of their fellows, is easily discovered. - -At that time, in fact, if any one desired knowledge beyond such as -could be obtained by his own observation, or by common conversation, -his first necessity was to learn the Latin language, inasmuch as -all the higher knowledge of the western world was contained in works -written in that language. Hence, Latin grammar, with logic and -rhetoric, studied through Latin, were the fundamentals of education. -With respect to the substance of the knowledge imparted through this -channel, the Jewish and Christian Scriptures, as interpreted and -supplemented by the Romish Church, were held to contain a complete and -infallibly true body of information. - -Theological dicta were, to the thinkers of those days, that which -the axioms and definitions of Euclid are to the geometers of these. -The business of the philosophers of the middle ages was to deduce -from the data furnished by the theologians, conclusions in accordance -with ecclesiastical decrees. They were allowed the high privilege of -showing, by logical process, how and why that which the Church said -was true, must be true. And if their demonstrations fell short of or -exceeded this limit, the Church was maternally ready to check their -aberrations, if need be, by the help of the secular arm. - -Between the two, our ancestors were furnished with a compact and -complete criticism of life. They were told how the world began and -how it would end; they learned that all material existence was but a -base and insignificant blot upon the fair face of the spiritual world, -and that nature was, to all intents and purposes, the playground of -the devil; they learned that the earth is the centre of the visible -universe, and that man is the cynosure of things terrestrial; and more -especially was it inculcated that the course of nature had no fixed -order, but that it could be, and constantly was, altered by the agency -of innumerable spiritual beings, good and bad, according as they were -moved by the deeds and prayers of men. The sum and substance of the -whole doctrine was to produce the conviction that the only thing really -worth knowing in this world was how to secure that place in a better -which, under certain conditions, the Church promised. - -Our ancestors had a living belief in this theory of life, and acted -upon it in their dealings with education, as in all other matters. -Culture meant saintliness—after the fashion of the saints of those -days; the education that led to it was, of necessity, theological; and -the way to theology lay through Latin. - -That the study of nature—further than was requisite for the -satisfaction of everyday wants—should have any bearing on human life -was far from the thoughts of men thus trained. Indeed, as nature had -been cursed for man’s sake, it was an obvious conclusion that those who -meddled with nature were likely to come into pretty close contact with -Satan. And, if any born scientific investigator followed his instincts, -he might safely reckon upon earning the reputation, and probably upon -suffering the fate, of a sorcerer. - -Had the western world been left to itself in Chinese isolation, there -is no saying how long this state of things might have endured. But, -happily, it was not left to itself. Even earlier than the thirteenth -century, the development of Moorish civilisation in Spain and the -great movement of the Crusades had introduced the leaven which, from -that day to this, has never ceased to work. At first, through the -intermediation of Arabic translations, afterwards, by the study of the -originals, the western nations of Europe became acquainted with the -writings of the ancient philosophers and poets, and, in time, with the -whole of the vast literature of antiquity. - -Whatever there was of high intellectual aspiration or dominant -capacity in Italy, France, Germany, and England, spent itself for -centuries in taking possession of the rich inheritance left by the dead -civilisations of Greece and Rome. Marvellously aided by the invention -of printing, classical learning spread and flourished. Those who -possessed it prided themselves on having attained the highest culture -then within the reach of mankind. - -And justly. For, saving Dante on his solitary pinnacle, there was no -figure in modern literature at the time of the Renascence to compare -with the men of antiquity; there was no art to compete with their -sculpture; there was no physical science but that which Greece had -created. Above all, there was no other example of perfect intellectual -freedom—of the unhesitating acceptance of reason as the sole guide to -truth and the supreme arbiter of conduct. - -The new learning necessarily soon exerted a profound influence upon -education. The language of the monks and schoolmen seemed little better -than gibberish to scholars fresh from Virgil and Cicero, and the study -of Latin was placed upon a new foundation. Moreover, Latin itself -ceased to afford the sole key to knowledge. The student who sought the -highest thought of antiquity, found only a second-hand reflection of -it in Roman literature, and turned his face to the full light of the -Greeks. And after a battle, not altogether dissimilar to that which -is at present being fought over the teaching of physical science, the -study of Greek was recognised as an essential element of all higher -education. - -Thus the Humanists, as they were called, won the day; and the great -reform which they effected was of incalculable service to mankind. -But the Nemesis of all reformers is finality; and the reformers of -education, like those of religion, fell into the profound, however -common, error of mistaking the beginning for the end of the work of -reformation. - -The representatives of the Humanists, in the nineteenth century, take -their stand upon classical education as the sole avenue to culture, as -firmly as if we were still in the age of Renascence. Yet, surely, the -present intellectual relations of the modern and the ancient worlds are -profoundly different from those which obtained three centuries ago. -Leaving aside the existence of a great and characteristically modern -literature, of modern painting, and, especially, of modern music, -there is one feature of the present state of the civilised world which -separates it more widely from the Renascence, than the Renascence was -separated from the middle ages. - -This distinctive character of our own times lies in the vast and -constantly increasing part which is played by natural knowledge. Not -only is our daily life shaped by it, not only does the prosperity -of millions of men depend upon it, but our whole theory of life has -long been influenced, consciously or unconsciously, by the general -conceptions of the universe, which have been forced upon us by physical -science. - -In fact, the most elementary acquaintance with the results of -scientific investigation shows us that they offer a broad and striking -contradiction to the opinions so implicitly credited and taught in the -middle ages. - -The notions of the beginning and the end of the world entertained -by our forefathers are no longer credible. It is very certain that -the earth is not the chief body in the material universe, and that -the world is not subordinated to man’s use. It is even more certain -that nature is the expression of a definite order with which nothing -interferes, and that the chief business of mankind is to learn that -order and govern themselves accordingly. Moreover this scientific -“criticism of life” presents itself to us with different credentials -from any other. It appeals not to authority, nor to what anybody -may have thought or said, but to nature. It admits that all our -interpretations of natural fact are more or less imperfect and -symbolic, and bids the learner seek for truth not among words but among -things. It warns us that the assertion which outstrips evidence is not -only a blunder but a crime. - -The purely classical education advocated by the representatives of -the Humanists in our day, gives no inkling of all this. A man may be -a better scholar than Erasmus, and know no more of the chief causes -of the present intellectual fermentation than Erasmus did. Scholarly -and pious persons, worthy of all respect, favour us with allocutions -upon the sadness of the antagonism of science to their mediæval way -of thinking, which betray an ignorance of the first principles of -scientific investigation, an incapacity for understanding what a man -of science means by veracity, and an unconsciousness of the weight of -established scientific truths, which is almost comical. - -There is no great force in the _tu quoque_ argument, or else the -advocates of scientific education might fairly enough retort upon the -modern Humanists that they may be learned specialists, but that they -possess no such sound foundation for a criticism of life as deserves -the name of culture. And, indeed, if we were disposed to be cruel, -we might urge that the Humanists have brought this reproach upon -themselves, not because they are too full of the spirit of the ancient -Greek, but because they lack it. - -The period of the Renascence is commonly called that of the “Revival of -Letters,” as if the influences then brought to bear upon the mind of -Western Europe had been wholly exhausted in the field of literature. -I think it is very commonly forgotten that the revival of science, -effected by the same agency, although less conspicuous, was not less -momentous. - -In fact, the few and scattered students of nature of that day picked -up the clue to her secrets exactly as it fell from the hands of the -Greeks a thousand years before. The foundations of mathematics were so -well laid by them, that our children learn their geometry from a book -written for the schools of Alexandria two thousand years ago. Modern -astronomy is the natural continuation and development of the work of -Hipparchus and of Ptolemy; modern physics of that of Democritus and of -Archimedes; it was long before modern biological science outgrew the -knowledge bequeathed to us by Aristotle, by Theophrastus, and by Galen. - -We cannot know all the best thoughts and sayings of the Greeks unless -we know what they thought about natural phenomena. We cannot fully -apprehend their criticism of life unless we understand the extent -to which that criticism was affected by scientific conceptions. We -falsely pretend to be the inheritors of their culture, unless we are -penetrated, as the best minds among them were, with an unhesitating -faith that the free employment of reason, in accordance with scientific -method, is the sole method of reaching truth. - -Thus I venture to think that the pretensions of our modern Humanists -to the possession of the monopoly of culture and to the exclusive -inheritance of the spirit of antiquity must be abated, if not -abandoned. But I should be very sorry that anything I have said should -be taken to imply a desire on my part to depreciate the value of -classical education, as it might be and as it sometimes is. The native -capacities of mankind vary no less than their opportunities; and while -culture is one, the road by which one man may best reach it is widely -different from that which is most advantageous to another. Again, -while scientific education is yet inchoate and tentative, classical -education is thoroughly well organised upon the practical experience -of generations of teachers. So that, given ample time for learning and -destination for ordinary life, or for a literary career, I do not think -that a young Englishman in search of culture can do better than follow -the course usually marked out for him, supplementing its deficiencies -by his own efforts. - -But for those who mean to make science their serious occupation; or who -intend to follow the profession of medicine; or who have to enter early -upon the business of life; for all these, in my opinion, classical -education is a mistake; and it is for this reason that I am glad to see -“mere literary education and instruction” shut out from the curriculum -of Sir Josiah Mason’s College, seeing that its inclusion would probably -lead to the introduction of the ordinary smattering of Latin and Greek. - -Nevertheless, I am the last person to question the importance of -genuine literary education, or to suppose that intellectual culture can -be complete without it. An exclusively scientific training will bring -about a mental twist as surely as an exclusively literary training. The -value of the cargo does not compensate for a ship’s being out of trim; -and I should be very sorry to think that the Scientific College would -turn out none but lop-sided men. - -There is no need, however, that such a catastrophe should happen. -Instruction in English, French, and German is provided, and thus the -three greatest literatures of the modern world are made accessible to -the student. - -French and German, and especially the latter language, are absolutely -indispensable to those who desire full knowledge in any department -of science. But even supposing that the knowledge of these languages -acquired is not more than sufficient for purely scientific purposes, -every Englishman has, in his native tongue, an almost perfect -instrument of literary expression; and, in his own literature, models -of every kind of literary excellence. If an Englishman cannot get -literary culture out of his Bible, his Shakspeare, his Milton, neither, -in my belief, will the profoundest study of Homer and Sophocles, Virgil -and Horace, give it to him. - -Thus, since the constitution of the College makes sufficient provision -for literary as well as for scientific education, and since artistic -instruction is also contemplated, it seems to me that a fairly complete -culture is offered to all who are willing to take advantage of it. - - -But I am not sure that at this point the “practical” man, scotched but -not slain, may ask what all this talk about culture has to do with -an Institution, the object of which is defined to be “to promote the -prosperity of the manufactures and the industry of the country.” He -may suggest that what is wanted for this end is not culture, nor even -a purely scientific discipline, but simply a knowledge of applied -science. - -I often wish that this phrase, “applied science,” had never been -invented. For it suggests that there is a sort of scientific knowledge -of direct practical use, which can be studied apart from another sort -of scientific knowledge, which is of no practical utility, and which -is termed “pure science.” But there is no more complete fallacy than -this. What people call applied science is nothing but the application -of pure science to particular classes of problems. It consists of -deductions from those general principles, established by reasoning and -observation, which constitute pure science. No one can safely make -these deductions until he has a firm grasp of the principles; and he -can obtain that grasp only by personal experience of the operations of -observation and of reasoning on which they are founded. - -Almost all the processes employed in the arts and manufactures fall -within the range either of physics or of chemistry. In order to improve -them, one must thoroughly understand them; and no one has a chance -of really understanding them, unless he has obtained that mastery -of principles and that habit of dealing with facts, which is given -by long-continued and well-directed purely scientific training in -the physical and the chemical laboratory. So that there really is no -question as to the necessity of purely scientific discipline, even if -the work of the College were limited by the narrowest interpretation of -its stated aims. - -And, as to the desirableness of a wider culture than that yielded -by science alone, it is to be recollected that the improvement of -manufacturing processes is only one of the conditions which contribute -to the prosperity of industry. Industry is a means and not an end; and -mankind work only to get something which they want. What that something -is depends partly on their innate, and partly on their acquired, -desires. - -If the wealth resulting from prosperous industry is to be spent upon -the gratification of unworthy desires, if the increasing perfection -of manufacturing processes is to be accompanied by an increasing -debasement of those who carry them on, I do not see the good of -industry and prosperity. - -Now it is perfectly true that men’s views of what is desirable depend -upon their characters; and that the innate proclivities to which we -give that name are not touched by any amount of instruction. But it -does not follow that even mere intellectual education may not, to an -indefinite extent, modify the practical manifestation of the characters -of men in their actions, by supplying them with motives unknown to the -ignorant. A pleasure-loving character will have pleasure of some sort; -but, if you give him the choice, he may prefer pleasures which do not -degrade him to those which do. And this choice is offered to every man, -who possesses in literary or artistic culture a never-failing source of -pleasures, which are neither withered by age, nor staled by custom, nor -embittered in the recollection by the pangs of self-reproach. - -If the Institution opened to-day fulfils the intention of its founder, -the picked intelligences among all classes of the population of -this district will pass through it. No child born in Birmingham, -henceforward, if he have the capacity to profit by the opportunities -offered to him, first in the primary and other schools, and afterwards -in the Scientific College, need fail to obtain, not merely the -instruction, but the culture most appropriate to the conditions of his -life. - -Within these walls, the future employer and the future artisan may -sojourn together for a while, and carry, through all their lives, the -stamp of the influences then brought to bear upon them. Hence, it is -not beside the mark to remind you, that the prosperity of industry -depends not merely upon the improvement of manufacturing processes, -not merely upon the ennobling of the individual character, but upon a -third condition, namely, a clear understanding of the conditions of -social life on the part of both the capitalist and the operative, and -their agreement upon common principles of social action. They must -learn that social phenomena are as much the expression of natural laws -as any others; that no social arrangements can be permanent unless -they harmonise with the requirements of social statics and dynamics; -and that, in the nature of things, there is an arbiter whose decisions -execute themselves. - -But this knowledge is only to be obtained by the application of -the methods of investigation adopted in physical researches to the -investigation of the phenomena of society. Hence, I confess, I should -like to see one addition made to the excellent scheme of education -propounded for the College, in the shape of provision for the teaching -of Sociology. For though we are all agreed that party politics are to -have no place in the instruction of the College; yet in this country, -practically governed as it is now by universal suffrage, every man who -does his duty must exercise political functions. And, if the evils -which are inseparable from the good of political liberty are to be -checked, if the perpetual oscillation of nations between anarchy and -despotism is to be replaced by the steady march of self-restraining -freedom; it will be because men will gradually bring themselves to deal -with political, as they now deal with scientific questions; to be as -ashamed of undue haste and partisan prejudice in the one case as in -the other; and to believe that the machinery of society is at least -as delicate as that of a spinning-jenny, and as little likely to be -improved by the meddling of those who have not taken the trouble to -master the principles of its action. - - -In conclusion, I am sure that I make myself the mouthpiece of all -present in offering to the venerable founder of the Institution, -which now commences its beneficent career, our congratulations on the -completion of his work; and in expressing the conviction, that the -remotest posterity will point to it as a crucial instance of the wisdom -which natural piety leads all men to ascribe to their ancestors. - - - - -II. - -UNIVERSITIES: ACTUAL AND IDEAL. - - -Elected by the suffrages of your four Nations, Rector of the ancient -University of which you are scholars, I take the earliest opportunity -which has presented itself since my restoration to health, of -delivering the Address which, by long custom, is expected of the holder -of my office. - -My first duty in opening that Address, is to offer you my most hearty -thanks for the signal honour you have conferred upon me—an honour -of which, as a man unconnected with you by personal or by national -ties, devoid of political distinction, and a plebeian who stands by -his order, I could not have dreamed. And it was the more surprising -to me, as the five-and-twenty years which have passed over my head -since I reached intellectual manhood, have been largely spent in no -half-hearted advocacy of doctrines which have not yet found favour -in the eyes of Academic respectability; so that, when the proposal -to nominate me for your Rector came, I was almost as much astonished -as was Hal o’ the Wynd, “who fought for his own hand,” by the Black -Douglas’s proffer of knighthood. And I fear that my acceptance must be -taken as evidence that, less wise than the Armourer of Perth, I have -not yet done with soldiering. - -In fact, if, for a moment, I imagined that your intention was simply, -in the kindness of your hearts, to do me honour; and that the Rector of -your University, like that of some other Universities, was one of those -happy beings who sit in glory for three years, with nothing to do for -it save the making of a speech, a conversation with my distinguished -predecessor soon dispelled the dream. I found that, by the constitution -of the University of Aberdeen, the incumbent of the Rectorate is, if -not a power, at any rate a potential energy; and that, whatever may -be his chances of success or failure, it is his duty to convert that -potential energy into a living force, directed towards such ends as may -seem to him conducive to the welfare of the corporation of which he is -the theoretical head. - -I need not tell you that your late Lord Rector took this view of -his position, and acted upon it with the comprehensive, far-seeing -insight into the actual condition and tendencies, not merely of his -own, but of other countries, which is his honourable characteristic -among statesmen. I have already done my best, and, as long as I hold -my office, I shall continue my endeavours, to follow in the path which -he trod; to do what in me lies, to bring this University nearer to the -ideal—alas, that I should be obliged to say ideal—of all Universities; -which, as I conceive, should be places in which thought is free from -all fetters; and in which all sources of knowledge, and all aids to -learning, should be accessible to all comers, without distinction of -creed or country, riches or poverty. - -Do not suppose, however, that I am sanguine enough to expect much to -come of any poor efforts of mine. If your annals take any notice of my -incumbency, I shall probably go down to posterity as the Rector who was -always beaten. But if they add, as I think they will, that my defeats -became victories in the hands of my successors, I shall be well content. - - -The scenes are shifting in the great theatre of the world. The act -which commenced with the Protestant Reformation is nearly played -out, and a wider and a deeper change than that effected three -centuries ago—a reformation, or rather a revolution of thought, the -extremes of which are represented by the intellectual heirs of John -of Leyden and of Ignatius Loyola, rather than by those of Luther -and of Leo—is waiting to come on, nay, visible behind the scenes to -those who have good eyes. Men are beginning, once more, to awake to -the fact that matters of belief and of speculation are of absolutely -infinite practical importance; and are drawing off from that sunny -country “where it is always afternoon”—the sleepy hollow of broad -indifferentism—to range themselves under their natural banners. -Change is in the air. It is whirling feather-heads into all sorts of -eccentric orbits, and filling the steadiest with a sense of insecurity. -It insists on reopening all questions and asking all institutions, -however venerable, by what right they exist, and whether they are, or -are not, in harmony with the real or supposed wants of mankind. And -it is remarkable that these searching inquiries are not so much forced -on institutions from without, as developed from within. Consummate -scholars question the value of learning; priests condemn dogma; and -women turn their backs upon man’s ideal of perfect womanhood, and seek -satisfaction in apocalyptic visions of some, as yet unrealised, epicene -reality. - -If there be a type of stability in this world, one would be inclined -to look for it in the old Universities of England. But it has been my -business of late to hear a good deal about what is going on in these -famous corporations; and I have been filled with astonishment by the -evidences of internal fermentation which they exhibit. If Gibbon -could revisit the ancient seat of learning of which he has written so -cavalierly, assuredly he would no longer speak of “the monks of Oxford -sunk in prejudice and port.” There, as elsewhere, port has gone out -of fashion, and so has prejudice—at least that particular fine, old, -crusted sort of prejudice to which the great historian alludes. - -Indeed, things are moving so fast in Oxford and Cambridge, that, for my -part, I rejoiced when the Royal Commission, of which I am a member, had -finished and presented the Report which related to these Universities; -for we should have looked like mere plagiarists, if, in consequence -of a little longer delay in issuing it, all the measures of reform -we proposed had been anticipated by the spontaneous action of the -Universities themselves. - -A month ago I should have gone on to say that one might speedily -expect changes of another kind in Oxford and Cambridge. A Commission -has been inquiring into the revenues of the many wealthy societies, in -more or less direct connection with the Universities, resident in those -towns. It is said that the Commission has reported, and that, for the -first time in recorded history, the nation, and perhaps the Colleges -themselves, will know what they are worth. And it was announced that a -statesman, who, whatever his other merits or defects, has aims above -the level of mere party fighting, and a clear vision into the most -complex practical problems, meant to deal with these revenues. - -But, _Bos locutus est._ That mysterious independent variable of -political calculation, Public Opinion—which some whisper is, in the -present case, very much the same thing as publican’s opinion—has willed -otherwise. The Heads may return to their wonted slumbers—at any rate -for a space. - -Is the spirit of change, which is working thus vigorously in the South, -likely to affect the Northern Universities, and if so, to what extent? -The violence of fermentation depends, not so much on the quantity of -the yeast, as on the composition of the wort, and its richness in -fermentable material; and, as a preliminary to the discussion of this -question, I venture to call to your minds the essential and fundamental -differences between the Scottish and the English type of University. - -Do not charge me with anything worse than official egotism, if I say -that these differences appear to be largely symbolised by my own -existence. There is no Rector in an English University. Now, the -organisation of the members of an University into Nations, with their -elective Rector, is the last relic of the primitive constitution of -Universities. The Rectorate was the most important of all offices in -that University of Paris, upon the model of which the University of -Aberdeen was fashioned; and which was certainly a great and flourishing -institution in the twelfth century. - -Enthusiasts for the antiquity of one of the two acknowledged parents -of all Universities, indeed, do not hesitate to trace the origin of -the “Studium Parisiense” up to that wonderful king of the Franks and -Lombards, Karl, surnamed the Great, whom we all called Charlemagne, and -believed to be a Frenchman, until a learned historian, by beneficent -iteration, taught us better. Karl is said not to have been much of a -scholar himself, but he had the wisdom of which knowledge is only the -servitor. And that wisdom enabled him to see that ignorance is one of -the roots of all evil. - -In the Capitulary which enjoins the foundation of monasterial and -cathedral schools, he says: “Right action is better than knowledge; -but in order to do what is right, we must know what is right.”[4] An -irrefragable truth, I fancy. Acting upon it, the king took pretty full -compulsory powers, and carried into effect a really considerable and -effectual scheme of elementary education through the length and breadth -of his dominions. - -No doubt the idolaters out by the Elbe, in what is now part of Prussia, -objected to the Frankish king’s measures; no doubt the priests, who had -never hesitated about sacrificing all unbelievers in their fantastic -deities and futile conjurations, were the loudest in chanting the -virtues of toleration; no doubt they denounced as a cruel persecutor -the man who would not allow them, however sincere they might be, to go -on spreading delusions which debased the intellect, as much as they -deadened the moral sense, and undermined the bonds of civil allegiance; -no doubt, if they had lived in these times, they would have been able -to show, with ease, that the king’s proceedings were totally contrary -to the best liberal principles. But it may be said, in justification of -the Teutonic ruler, first, that he was born before those principles, -and did not suspect that the best way of getting disorder into order -was to let it alone; and, secondly, that his rough and questionable -proceedings did, more or less, bring about the end he had in view. For, -in a couple of centuries, the schools he sowed broadcast produced their -crop of men, thirsting for knowledge and craving for culture. Such men -gravitating towards Paris, as a light amidst the darkness of evil days, -from Germany, from Spain, from Britain, and from Scandinavia, came -together by natural affinity. By degrees they banded themselves into a -society, which, as its end was the knowledge of all things knowable, -called itself a “_Studium Generale_;” and when it had grown into a -recognised corporation, acquired the name of “_Universitas Studii -Generalis_,” which, mark you, means not a “Useful Knowledge Society,” -but a “Knowledge-of-things-in-general Society.” - -And thus the first “University,” at any rate on this side of the Alps, -came into being. Originally it had but one Faculty, that of Arts. Its -aim was to be a centre of knowledge and culture; not to be, in any -sense, a technical school. - -The scholars seem to have studied Grammar, Logic, and Rhetoric; -Arithmetic and Geometry; Astronomy; Theology; and Music. Thus, their -work, however imperfect and faulty, judged by modern lights, it may -have been, brought them face to face with all the leading aspects of -the many-sided mind of man. For these studies did really contain, at -any rate in embryo—sometimes, it may be, in caricature—what we now call -Philosophy, Mathematical and Physical Science, and Art. And I doubt if -the curriculum of any modern University shows so clear and generous -a comprehension of what is meant by culture, as this old Trivium and -Quadrivium does. - -The students who had passed through the University course, and had -proved themselves competent to teach, became masters and teachers of -their younger brethren. Whence the distinction of Masters and Regents -on the one hand, and Scholars on the other. - -Rapid growth necessitated organisation. The Masters and Scholars of -various tongues and countries grouped themselves into four Nations; and -the Nations, by their own votes at first, and subsequently by those -of their Procurators, or representatives, elected their supreme head -and governor, the Rector—at that time the sole representative of the -University, and a very real power, who could defy Provosts interfering -from without; or could inflict even corporal punishment on disobedient -members within the University. - -Such was the primitive constitution of the University of Paris. It is -in reference to this original state of things that I have spoken of the -Rectorate, and all that appertains to it, as the sole relic of that -constitution. - -But this original organisation did not last long. Society was not -then, any more than it is now, patient of culture, as such. It says to -everything, “Be useful to me, or away with you.” And to the learned, -the unlearned man said then, as he does now, “What is the use of all -your learning, unless you can tell me what I want to know? I am here -blindly groping about, and constantly damaging myself by collision -with three mighty powers, the power of the invisible God, the power -of my fellow Man, and the power of brute Nature. Let your learning -be turned to the study of these powers, that I may know how I am to -comport myself with regard to them.” In answer to this demand, some -of the Masters of the Faculty of Arts devoted themselves to the study -of Theology, some to that of Law, and some to that of Medicine; and -they became Doctors—men learned in those technical, or, as we now call -them, professional, branches of knowledge. Like cleaving to like, the -Doctors formed schools, or Faculties, of Theology, Law, and Medicine, -which sometimes assumed airs of superiority over their parent, the -Faculty of Arts, though the latter always asserted and maintained its -fundamental supremacy. - -The Faculties arose by process of natural differentiation out of the -primitive University. Other constituents, foreign to its nature, -were speedily grafted upon it. One of these extraneous elements was -forced into it by the Roman Church, which in those days asserted with -effect, that which it now asserts, happily without any effect in these -realms, its right of censorship and control over all teaching. The -local habitation of the University lay partly in the lands attached to -the monastery of S. Geneviève, partly in the diocese of the Bishop of -Paris; and he who would teach must have the licence of the Abbot, or of -the Bishop, as the nearest representative of the Pope, so to do, which -licence was granted by the Chancellors of these Ecclesiastics. - -Thus, if I am what archæologists call a “survival” of the primitive -head and ruler of the University, your Chancellor stands in the same -relation to the Papacy; and, with all respect for his Grace, I think -I may say that we both look terribly shrunken when compared with our -great originals. - -Not so is it with a second foreign element, which silently dropped -into the soil of Universities, like the grain of mustard-seed in the -parable; and, like that grain, grew into a tree, in whose branches -a whole aviary of fowls took shelter. That element is the element -of Endowment. It differed from the preceding, in its original design -to serve as a prop to the young plant, not to be a parasite upon it. -The charitable and the humane, blessed with wealth, were very early -penetrated by the misery of the poor student. And the wise saw that -intellectual ability is not so common or so unimportant a gift that it -should be allowed to run to waste upon mere handicrafts and chares. -The man who was a blessing to his contemporaries, but who so often has -been converted into a curse, by the blind adherence of his posterity -to the letter, rather than to the spirit, of his wishes—I mean the -“pious founder”—gave money and lands, that the student, who was rich in -brain and poor in all else, might be taken from the plough or from the -stithy, and enabled to devote himself to the higher service of mankind; -and built colleges and halls in which he might be not only housed and -fed, but taught. - -The Colleges were very generally placed in strict subordination to the -University by their founders; but, in many cases, their endowment, -consisting of land, has undergone an “unearned increment,” which has -given these societies a continually increasing weight and importance -as against the unendowed, or fixedly endowed, University. In Pharaoh’s -dream, the seven lean kine eat up the seven fat ones. In the reality of -historical fact, the fat Colleges have eaten up the lean Universities. - -Even here in Aberdeen, though the causes at work may have been -somewhat different, the effects have been similar; and you see how -much more substantial an entity is the Very Reverend the Principal, -analogue, if not homologue, of the Principals of King’s College, than -the Rector, lineal representative of the ancient monarchs of the -University, though now, little more than a “king of shreds and patches.” - -Do not suppose that, in thus briefly tracing the process of University -metamorphosis, I have had any intention of quarrelling with its -results. Practically, it seems to me that the broad changes effected in -1858 have given the Scottish Universities a very liberal constitution, -with as much real approximation to the primitive state of things as -is at all desirable. If your fat kine have eaten the lean, they have -not lain down to chew the cud ever since. The Scottish Universities, -like the English, have diverged widely enough from their primitive -model; but I cannot help thinking that the northern form has remained -more faithful to its original, not only in constitution, but, what is -more to the purpose, in view of the cry for change, in the practical -application of the endowments connected with it. - -In Aberdeen, these endowments are numerous, but so small that, taken -altogether, they are not equal to the revenue of a single third-rate -English college. They are scholarships, not fellowships; aids to -do work—not rewards for such work as it lies within the reach of -an ordinary, or even an extraordinary, young man to do. You do not -think that passing a respectable examination is a fair equivalent -for an income, such as many a gray-headed veteran, or clergyman, -would envy; and which is larger than the endowment of many Regius -chairs. You do not care to make your University a school of manners -for the rich; of sports for the athletic; or a hot-bed of high-fed, -hypercritical refinement, more destructive to vigour and originality -than are starvation and oppression. No; your little Bursaries of ten -and twenty (I believe even fifty) pounds a year, enable any boy who -has shown ability in the course of his education in those remarkable -primary schools, which have made Scotland the power she is, to obtain -the highest culture the country can give him; and when he is armed and -equipped, his Spartan Alma Mater tells him that, so far, he has had his -wages for his work, and that he may go and earn the rest. - -When I think of the host of pleasant, monied, well-bred young -gentlemen, who do a little learning and much boating by Cam and Isis, -the vision is a pleasant one; and, as a patriot, I rejoice that the -youth of the upper and richer classes of the nation receive a wholesome -and a manly training, however small may be the modicum of knowledge -they gather, in the intervals of this, their serious business. I admit, -to the full, the social and political value of that training. But, when -I proceed to consider that these young men may be said to represent -the great bulk of what the Colleges have to show for their enormous -wealth, plus, at least, a hundred and fifty pounds a year apiece which -each undergraduate costs his parents or guardians, I feel inclined -to ask, whether the rate-in-aid of the education of the wealthy and -professional classes, thus levied on the resources of the community, -is not, after all, a little heavy? And, still further, I am tempted -to inquire what has become of the indigent scholars, the sons of the -masses of the people whose daily labour just suffices to meet their -daily wants, for whose benefit these rich foundations were largely, -if not mainly, instituted? It seems as if Pharaoh’s dream had been -rigorously carried out, and that even the fat scholar has eaten the -lean one. And when I turn from this picture to the no less real vision -of many a brave and frugal Scotch boy, spending his summer in hard -manual labour, that he may have the privilege of wending his way in -autumn to this University, with a bag of oatmeal, ten pounds in his -pocket, and his own stout heart to depend upon through the northern -winter; not bent on seeking - - “The bubble reputation at the cannon’s mouth,” - -but determined to wring knowledge from the hard hands of penury; when -I see him win through all such outward obstacles to positions of wide -usefulness and well-earned fame; I cannot but think that, in essence, -Aberdeen has departed but little from the primitive intention of the -founders of Universities, and that the spirit of reform has so much to -do on the other side of the Border, that it may be long before he has -leisure to look this way. - -As compared with other actual Universities, then, Aberdeen, may, -perhaps, be well satisfied with itself. But do not think me an -impracticable dreamer, if I ask you not to rest and be thankful in -this state of satisfaction; if I ask you to consider awhile, how this -actual good stands related to that ideal better, towards which both men -and institutions must progress, if they would not retrograde. - -In an ideal University, as I conceive it, a man should be able to -obtain instruction in all forms of knowledge, and discipline in the -use of all the methods by which knowledge is obtained. In such an -University, the force of living example should fire the student with a -noble ambition to emulate the learning of learned men, and to follow -in the footsteps of the explorers of new fields of knowledge. And the -very air he breathes should be charged with that enthusiasm for truth, -that fanaticism of veracity, which is a greater possession than much -learning; a nobler gift than the power of increasing knowledge; by -so much greater and nobler than these, as the moral nature of man is -greater than the intellectual; for veracity is the heart of morality. - -But the man who is all morality and intellect, although he may be good -and even great, is, after all, only half a man. There is beauty in the -moral world and in the intellectual world; but there is also a beauty -which is neither moral nor intellectual—the beauty of the world of Art. -There are men who are devoid of the power of seeing it, as there are -men who are born deaf and blind, and the loss of those, as of these, -is simply infinite. There are others in whom it is an overpowering -passion; happy men, born with the productive, or at lowest, the -appreciative, genius of the Artist. But, in the mass of mankind, -the Æsthetic faculty, like the reasoning power and the moral sense, -needs to be roused, directed, and cultivated; and I know not why the -development of that side of his nature, through which man has access to -a perennial spring of ennobling pleasure, should be omitted from any -comprehensive scheme of University education. - -All Universities recognise Literature in the sense of the old Rhetoric, -which is art incarnate in words. Some, to their credit, recognise Art -in its narrower sense, to a certain extent, and confer degrees for -proficiency in some of its branches. If there are Doctors of Music, why -should there be no Masters of Painting, of Sculpture, of Architecture? -I should like to see Professors of the Fine Arts in every University; -and instruction in some branch of their work made a part of the Arts -curriculum. - -I just now expressed the opinion that, in our ideal University, a man -should be able to obtain instruction in all forms of knowledge. Now, by -“forms of knowledge” I mean the great classes of things knowable; of -which the first, in logical, though not in natural, order is knowledge -relating to the scope and limits of the mental faculties of man; a form -of knowledge which, in its positive aspect, answers pretty much to -Logic and part of Psychology, while, on its negative and critical side, -it corresponds with Metaphysics. - -A second class comprehends all that knowledge which relates to -man’s welfare, so far as it is determined by his own acts, or what -we call his conduct. It answers to Moral and Religious philosophy. -Practically, it is the most directly valuable of all forms of -knowledge, but speculatively, it is limited and criticised by that -which precedes and by that which follows it in my order of enumeration. - -A third class embraces knowledge of the phenomena of the Universe, as -that which lies about the individual man: and of the rules which those -phenomena are observed to follow in the order of their occurrence, -which we term the laws of Nature. - -This is what ought to be called Natural Science, or Physiology, though -those terms are hopelessly diverted from such a meaning; and it -includes all exact knowledge of natural fact, whether Mathematical, -Physical, Biological, or Social. - -Kant has said that the ultimate object of all knowledge is to give -replies to these three questions: What can I do? What ought I to do? -What may I hope for? The forms of knowledge which I have enumerated, -should furnish such replies as are within human reach, to the first -and second of these questions. While to the third, perhaps the wisest -answer is, “Do what you can to do what you ought, and leave hoping and -fearing alone.” - -If this be a just and an exhaustive classification of the forms of -knowledge, no question as to their relative importance, or as to the -superiority of one to the other, can be seriously raised. - -On the face of the matter, it is absurd to ask whether it is more -important to know the limits of one’s powers; or the ends for which -they ought to be exerted; or the conditions under which they must be -exerted. One may as well inquire which of the terms of a Rule of Three -sum one ought to know, in order to get a trustworthy result. Practical -life is such a sum, in which your duty multiplied into your capacity, -and divided by your circumstances, gives you the fourth term in the -proportion, which is your deserts, with great accuracy. All agree, I -take it, that men ought to have these three kinds of knowledge. The -so-called “conflict of studies” turns upon the question of how they may -best be obtained. - -The founders of Universities held the theory that the Scriptures and -Aristotle taken together, the latter being limited by the former, -contained all knowledge worth having, and that the business of -philosophy was to interpret and co-ordinate these two. I imagine -that in the twelfth century this was a very fair conclusion from -known facts. Nowhere in the world, in those days, was there such an -encyclopædia of knowledge of all three classes, as is to be found in -those writings. The scholastic philosophy is a wonderful monument of -the patience and ingenuity with which the human mind toiled to build up -a logically consistent theory of the Universe, out of such materials. -And that philosophy is by no means dead and buried, as many vainly -suppose. On the contrary, numbers of men of no mean learning and -accomplishment, and sometimes of rare power and subtlety of thought, -hold by it as the best theory of things which has yet been stated. And, -what is still more remarkable, men who speak the language of modern -philosophy, nevertheless think the thoughts of the schoolmen. “The -voice is the voice of Jacob, but the hands are the hands of Esau.” -Every day I hear “Cause,” “Law,” “Force,” “Vitality,” spoken of as -entities, by people who can enjoy Swift’s joke about the meat-roasting -quality of the smoke-jack, and comfort themselves with the reflection -that they are not even as those benighted schoolmen. - -Well, this great system had its day, and then it was sapped and mined -by two influences. The first was the study of classical literature, -which familiarised men with methods of philosophising; with conceptions -of the highest Good; with ideas of the order of Nature; with notions of -Literary and Historical Criticism; and, above all, with visions of Art, -of a kind which not only would not fit into the scholastic scheme, but -showed them a pre-Christian, and indeed altogether un-Christian world, -of such grandeur and beauty that they ceased to think of any other. -They were as men who had kissed the Fairy Queen, and wandering with her -in the dim loveliness of the underworld, cared not to return to the -familiar ways of home and fatherland, though they lay, at arm’s length, -overhead. Cardinals were more familiar with Virgil than with Isaiah; -and Popes laboured, with great success, to re-paganise Rome. - -The second influence was the slow, but sure, growth of the physical -sciences. It was discovered that some results of speculative thought, -of immense practical and theoretical importance, can be verified by -observation; and are always true, however severely they may be tested. -Here, at any rate, was knowledge, to the certainty of which no -authority could add, or take away, one jot or tittle, and to which the -tradition of a thousand years was as insignificant as the hearsay of -yesterday. To the scholastic system, the study of classical literature -might be inconvenient and distracting, but it was possible to hope that -it could be kept within bounds. Physical science, on the other hand, -was an irreconcilable enemy, to be excluded at all hazards. The College -of Cardinals has not distinguished itself in Physics or Physiology; and -no Pope has, as yet, set up public laboratories in the Vatican. - -People do not always formulate the beliefs on which they act. The -instinct of fear and dislike is quicker than the reasoning process; -and I suspect that, taken in conjunction with some other causes, such -instinctive aversion is at the bottom of the long exclusion of any -serious discipline in the physical sciences from the general curriculum -of Universities; while, on the other hand, classical literature has -been gradually made the backbone of the Arts course. - -I am ashamed to repeat here what I have said elsewhere, in season -and out of season, respecting the value of Science as knowledge and -discipline. But the other day I met with some passages in the Address -to another Scottish University, of a great thinker, recently lost to -us, which express so fully, and yet so tersely, the truth in this -matter, that I am fain to quote them:— - -“To question all things;—never to turn away from any difficulty; -to accept no doctrine either from ourselves or from other people -without a rigid scrutiny by negative criticism; letting no fallacy, -or incoherence, or confusion of thought step by unperceived; above -all, to insist upon having the meaning of a word clearly understood -before using it, and the meaning of a proposition before assenting -to it;—these are the lessons we learn” from workers in Science. -“With all this vigorous management of the negative element, they -inspire no scepticism about the reality of truth or indifference to -its pursuit. The noblest enthusiasm, both for the search after truth -and for applying it to its highest uses, pervades those writers.” -“In cultivating, therefore,” science as an essential ingredient in -education, “we are all the while laying an admirable foundation for -ethical and philosophical culture.”[5] - -The passages I have quoted were uttered by John Stuart Mill; but you -cannot hear inverted commas, and it is therefore right that I should -add, without delay, that I have taken the liberty of substituting -“workers in science” for “ancient dialecticians,” and “Science as an -essential ingredient in education” for “the ancient languages as our -best literary education.” Mill did, in fact, deliver a noble panegyric -upon classical studies. I do not doubt its justice, nor presume to -question its wisdom. But I venture to maintain that no wise or just -judge, who has a knowledge of the facts, will hesitate to say that it -applies with equal force to scientific training. - -But it is only fair to the Scottish Universities to point out that -they have long understood the value of Science as a branch of general -education. I observe, with the greatest satisfaction, that candidates -for the degree of Master of Arts in this University are required to -have a knowledge, not only of Mental and Moral Philosophy, and of -Mathematics and Natural Philosophy, but of Natural History, in addition -to the ordinary Latin and Greek course; and that a candidate may take -honours in these subjects and in Chemistry. - -I do not know what the requirements of your examiners may be, but I -sincerely trust they are not satisfied with a mere book knowledge of -these matters. For my own part, I would not raise a finger, if I could -thereby introduce mere book work in science into every Arts curriculum -in the country. Let those who want to study books devote themselves -to Literature, in which we have the perfection of books, both as to -substance and as to form. If I may paraphrase Hobbes’s well-known -aphorism, I would say that “books are the money of Literature, but only -the counters of Science,” Science (in the sense in which I now use the -term) being the knowledge of fact, of which every verbal description -is but an incomplete and symbolic expression. And be assured that no -teaching of science is worth anything, as a mental discipline, which is -not based upon direct perception of the facts, and practical exercise -of the observing and logical faculties upon them. Even in such a simple -matter as the mere comprehension of form, ask the most practised and -widely informed anatomist what is the difference between his knowledge -of a structure which he has read about, and his knowledge of the same -structure when he has seen it for himself; and he will tell you that -the two things are not comparable—the difference is infinite. Thus I -am very strongly inclined to agree with some learned school-masters -who say that, in their experience, the teaching of science is all -waste time. As they teach it, I have no doubt it is. But to teach it -otherwise, requires an amount of personal labour and a development of -means and appliances, which must strike horror and dismay into a man -accustomed to mere book work; and who has been in the habit of teaching -a class of fifty without much strain upon his energies. And this is one -of the real difficulties in the way of the introduction of physical -science into the ordinary University course, to which I have alluded. -It is a difficulty which will not be overcome, until years of patient -study have organised scientific teaching as well as, or I hope better -than, classical teaching has been organised hitherto. - -A little while ago, I ventured to hint a doubt as to the perfection -of some of the arrangements in the ancient Universities of England; -but, in their provision for giving instruction in Science as such, -and without direct reference to any of its practical applications, -they have set a brilliant example. Within the last twenty years, -Oxford alone has sunk more than a hundred and twenty thousand pounds -in building and furnishing Physical, Chemical, and Physiological -Laboratories, and a magnificent Museum, arranged with an almost -luxurious regard for the needs of the student. Cambridge, less rich, -but aided by the munificence of her Chancellor, is taking the same -course; and, in a few years, it will be for no lack of the means and -appliances of sound teaching, if the mass of English University men -remain in their present state of barbarous ignorance of even the -rudiments of scientific culture. - -Yet another step needs to be made before Science can be said to have -taken its proper place in the Universities. That is its recognition -as a Faculty, or branch of study demanding recognition and special -organisation, on account of its bearing on the wants of mankind. The -Faculties of Theology, Law, and Medicine, are technical schools, -intended to equip men who have received general culture, with the -special knowledge which is needed for the proper performance of the -duties of clergymen, lawyers, and medical practitioners. - -When the material well-being of the country depended upon rude pasture -and agriculture, and still ruder mining; in the days when all the -innumerable applications of the principles of physical science to -practical purposes were non-existent even as dreams; days which men -living may have heard their fathers speak of; what little physical -science could be seen to bear directly upon human life, lay within the -province of Medicine. Medicine was the foster-mother of Chemistry, -because it has to do with the preparation of drugs and the detection -of poisons; of Botany, because it enabled the physician to recognise -medicinal herbs; of Comparative Anatomy and Physiology, because the man -who studied Human Anatomy and Physiology for purely medical purposes -was led to extend his studies to the rest of the animal world. - -Within my recollection, the only way in which a student could obtain -anything like a training in Physical Science, was by attending the -lectures of the Professors of Physical and Natural Science attached to -the Medical Schools. But, in the course of the last thirty years, both -foster-mother and child have grown so big, that they threaten not only -to crush one another, but to press the very life out of the unhappy -student who enters the nursery; to the great detriment of all three. - -I speak in the presence of those who know practically what medical -education is; for I may assume that a large proportion of my hearers -are more or less advanced students of medicine. I appeal to the most -industrious and conscientious among you, to those who are most deeply -penetrated with a sense of the extremely serious responsibilities which -attach to the calling of a medical practitioner, when I ask whether, -out of the four years which you devote to your studies, you ought to -spare even so much as an hour for any work which does not tend directly -to fit you for your duties? - -Consider what that work is. Its foundation is a sound and practical -acquaintance with the structure of the human organism, and with the -modes and conditions of its action in health. I say a sound and -practical acquaintance, to guard against the supposition that my -intention is to suggest that you ought all to be minute anatomists and -accomplished physiologists. The devotion of your whole four years to -Anatomy and Physiology alone, would be totally insufficient to attain -that end. What I mean is, the sort of practical, familiar, finger-end -knowledge which a watchmaker has of a watch, and which you expect that -craftsman, as an honest man, to have, when you entrust a watch that -goes badly, to him. It is a kind of knowledge which is to be acquired, -not in the lecture-room, nor in the library, but in the dissecting-room -and the laboratory. It is to be had, not by sharing your attention -between these and sundry other subjects, but by concentrating your -minds, week after week, and month after month, six or seven hours a -day, upon all the complexities of organ and function, until each of the -greater truths of anatomy and physiology has become an organic part of -your minds—until you would know them if you were roused and questioned -in the middle of the night, as a man knows the geography of his native -place and the daily life of his home. That is the sort of knowledge -which, once obtained, is a life-long possession. Other occupations may -fill your minds—it may grow dim, and seem to be forgotten—but there it -is, like the inscription on a battered and defaced coin, which comes -out when you warm it. - -If I had the power to remodel Medical Education, the first two years of -the medical curriculum should be devoted to nothing but such thorough -study of Anatomy and Physiology, with Physiological Chemistry and -Physics; the student should then pass a real, practical examination in -these subjects; and, having gone through that ordeal satisfactorily, -he should be troubled no more with them. His whole mind should then be -given with equal intentness, to Therapeutics, in its broadest sense, -to Practical Medicine and to Surgery, with instruction in Hygiene and -in Medical Jurisprudence; and of these subjects only—surely there are -enough of them—should he be required to show a knowledge in his final -examination. - -I cannot claim any special property in this theory of what the medical -curriculum should be, for I find that views, more or less closely -approximating these, are held by all who have seriously considered the -very grave and pressing question of Medical Reform; and have, indeed, -been carried into practice, to some extent, by the most enlightened -Examining Boards. I have heard but two kinds of objections to them. -There is, first, the objection of vested interests, which I will not -deal with here, because I want to make myself as pleasant as I can, and -no discussions are so unpleasant as those which turn on such points. -And there is, secondly, the much more respectable objection, which -takes the general form of the reproach that, in thus limiting the -curriculum, we are seeking to narrow it. We are told that the medical -man ought to be a person of good education and general information, -if his profession is to hold its own among other professions; that -he ought to know Botany, or else, if he goes abroad, he will not be -able to tell poisonous fruits from edible ones; that he ought to -know drugs, as a druggist knows them, or he will not be able to tell -sham bark and senna from the real articles; that he ought to know -Zoology, because—well, I really have never been able to learn exactly -why he is to be expected to know zoology. There is, indeed, a popular -superstition, that doctors know all about things that are queer or -nasty to the general mind, and may, therefore, be reasonably expected -to know the “barbarous binomials” applicable to snakes, snails, and -slugs; an amount of information with which the general mind is usually -completely satisfied. And there is a scientific superstition that -Physiology is largely aided by Comparative Anatomy—a superstition -which, like most superstitions, once had a grain of truth at bottom; -but the grain has become homœopathic, since Physiology took its modern -experimental development, and became what it is now, the application -of the principles of Physics and Chemistry to the elucidation of the -phenomena of life. - -I hold as strongly as any one can do, that the medical practitioner -ought to be a person of education and good general culture; but I -also hold by the old theory of a Faculty, that a man should have his -general culture before he devotes himself to the special studies of -that Faculty; and I venture to maintain, that, if the general culture -obtained in the Faculty of Arts were what it ought to be, the student -would have quite as much knowledge of the fundamental principles of -Physics, of Chemistry, and of Biology, as he needs, before he commenced -his special medical studies. - -Moreover, I would urge, that a thorough study of Human Physiology is, -in itself, an education broader and more comprehensive than much that -passes under that name. There is no side of the intellect which it does -not call into play, no region of human knowledge into which either its -roots, or its branches, do not extend; like the Atlantic between the -Old and the New Worlds, its waves wash the shores of the two worlds -of matter and of mind; its tributary streams flow from both; through -its waters, as yet unfurrowed by the keel of any Columbus, lies the -road, if such there be, from the one to the other; far away from that -North-west Passage of mere speculation, in which so many brave souls -have been hopelessly frozen up. - -But whether I am right or wrong about all this, the patent fact of the -limitation of time remains. As the song runs:— - - “If a man could be sure - That his life would endure - For the space of a thousand long years——” - -he might do a number of things not practicable under present -conditions. Methuselah might, with much propriety, have taken half a -century to get his doctor’s degree; and might, very fairly, have been -required to pass a practical examination upon the contents of the -British Museum, before commencing practice as a promising young fellow -of two hundred, or thereabouts. But you have four years to do your -work in, and are turned loose, to save or slay, at two or three and -twenty. - -Now, I put it to you, whether you think that, when you come down to -the realities of life—when you stand by the sick-bed, racking your -brains for the principles which shall furnish you with the means of -interpreting symptoms, and forming a rational theory of the condition -of your patient, it will be satisfactory for you to find that those -principles are not there—although, to use the examination slang which -is unfortunately too familiar to me, you can quite easily “give -an account of the leading peculiarities of the _Marsupialia_,” or -“enumerate the chief characters of the _Compositæ_,” or “state the -class and order of the animal from which Castoreum is obtained.” - -I really do not think that state of things will be satisfactory -to you; I am very sure it will not be so to your patient. Indeed, -I am so narrow-minded myself, that if I had to choose between two -physicians—one who did not know whether a whale is a fish or not, and -could not tell gentian from ginger, but did understand the applications -of the institutes of medicine to his art; while the other, like -Talleyrand’s doctor, “knew everything, even a little physic”—with all -my love for breadth of culture, I should assuredly consult the former. - -It is not pleasant to incur the suspicion of an inclination to injure -or depreciate particular branches of knowledge. But the fact that -one of those which I should have no hesitation in excluding from the -medical curriculum, is that to which my own life has been specially -devoted, should, at any rate, defend me from the suspicion of being -urged to this course by any but the very gravest considerations of the -public welfare. - -And I should like, further, to call your attention to the important -circumstance that, in thus proposing the exclusion of the study of such -branches of knowledge as Zoology and Botany, from those compulsory upon -the medical student, I am not, for a moment, suggesting their exclusion -from the University. I think that sound and practical instruction in -the elementary facts and broad principles of Biology should form part -of the Arts Curriculum: and here, happily, my theory is in entire -accordance with your practice. Moreover, as I have already said, I have -no sort of doubt that, in view of the relation of Physical Science -to the practical life of the present day, it has the same right as -Theology, Law, and Medicine, to a Faculty of its own in which men shall -be trained to be professional men of science. It may be doubted whether -Universities are the places for technical schools of Engineering, or -Applied Chemistry, or Agriculture. But there can surely be little -question, that instruction in the branches of Science which lie at the -foundation of these Arts, of a far more advanced and special character -than could, with any propriety, be included in the ordinary Arts -Curriculum, ought to be obtainable by means of a duly organised Faculty -of Science in every University. - -The establishment of such a Faculty would have the additional advantage -of providing, in some measure, for one of the greatest wants of our -time and country. I mean the proper support and encouragement of -original research. - -The other day, an emphatic friend of mine committed himself to the -opinion that, in England, it is better for a man’s worldly prospects -to be a drunkard, than to be smitten with the divine dipsomania of the -original investigator. I am inclined to think he was not far wrong. -And, be it observed, that the question is not, whether such a man shall -be able to make as much out of his abilities as his brother, of like -ability, who goes into Law, or Engineering, or Commerce; it is not a -question of “maintaining a due number of saddle horses,” as George -Eliot somewhere puts it—it is a question of living or starving. - -If a student of my own subject shows power and originality, I dare not -advise him to adopt a scientific career; for, supposing he is able to -maintain himself until he has attained distinction, I cannot give him -the assurance that any amount of proficiency in the Biological Sciences -will be convertible into, even the most modest, bread and cheese. -And I believe that the case is as bad, or perhaps worse, with other -branches of Science. In this respect Britain, whose immense wealth -and prosperity hang upon the thread of Applied Science, is far behind -France, and infinitely behind Germany. - -And the worst of it is, that it is very difficult to see one’s way to -any immediate remedy for this state of affairs which shall be free from -a tendency to become worse than the disease. - -Great schemes for the Endowment of Research have been proposed. It has -been suggested, that Laboratories for all branches of Physical Science, -provided with every apparatus needed by the investigator, shall be -established by the State: and shall be accessible, under due conditions -and regulations, to all properly qualified persons. I see no objection -to the principle of such a proposal. If it be legitimate to spend great -sums of money on public Libraries and public collections of Painting -and Sculpture, in aid of the man of letters, or the Artist, or for the -mere sake of affording pleasure to the general public, I apprehend that -it cannot be illegitimate to do as much for the promotion of scientific -investigation. To take the lowest ground, as a mere investment of -money, the latter is likely to be much more immediately profitable. To -my mind, the difficulty in the way of such schemes is not theoretical, -but practical. Given the laboratories, how are the investigators to be -maintained? What career is open to those who have been thus encouraged -to leave bread-winning pursuits? If they are to be provided for by -endowment, we come back to the College Fellowship system, the results -of which, for Literature, have not been so brilliant that one would -wish to see it extended to Science; unless some much better securities, -than at present exist, can be taken that it will foster real work. -You know that among the Bees, it depends on the kind of cell in which -the egg is deposited, and the quantity and quality of food which is -supplied to the grub, whether it shall turn out a busy little worker -or a big idle queen. And, in the human hive, the cells of the endowed -larvæ are always tending to enlarge, and their food to improve, until -we get queens, beautiful to behold, but which gather no honey and build -no comb. - -I do not say that these difficulties may not be overcome, but their -gravity is not to be lightly estimated. - -In the meanwhile, there is one step in the direction of the endowment -of research which is free from such objections. It is possible to place -the scientific inquirer in a position in which he shall have ample -leisure and opportunity for original work, and yet shall give a fair -and tangible equivalent for those privileges. The establishment of a -Faculty of Science in every University, implies that of a corresponding -number of Professorial chairs, the incumbents of which need not be -so burdened with teaching as to deprive them of ample leisure for -original work. I do not think that it is any impediment to an original -investigator to have to devote a moderate portion of his time to -lecturing, or superintending practical instruction. On the contrary, -I think it may be, and often is, a benefit to be obliged to take a -comprehensive survey of your subject; or to bring your results to a -point, and give them, as it were, a tangible objective existence. The -besetting sins of the investigator are two: the one is the desire to -put aside a subject, the general bearings of which he has mastered -himself, and pass on to something which has the attraction of novelty; -and the other, the desire for too much perfection, which leads him to - - “Add and alter many times, - Till all be ripe and rotten;” - -to spend the energies which should be reserved for action, in whitening -the decks and polishing the guns. - -The obligation to produce results for the instruction of others, seems -to me to be a more effectual check on these tendencies, than even the -love of usefulness or the ambition for fame. - -But supposing the Professorial forces of our University to be -duly organised, there remains an important question, relating -to the teaching power, to be considered. Is the Professorial -system—the system, I mean, of teaching in the lecture-room alone, -and leaving the student to find his own way when he is outside the -lecture-room—adequate to the wants of learners? In answering this -question, I confine myself to my own province, and I venture to -reply for Physical Science, assuredly and undoubtedly, No. As I have -already intimated, practical work in the Laboratory is absolutely -indispensable, and that practical work must be guided and superintended -by a sufficient staff of Demonstrators, who are for Science what Tutors -are for other branches of study. And there must be a good supply of -such Demonstrators. I doubt if the practical work of more than twenty -students can be properly superintended by one Demonstrator. If we -take the working day at six hours, that is less than twenty minutes -apiece—not a very large allowance of time for helping a dull man, for -correcting an inaccurate one, or even for making an intelligent student -clearly apprehend what he is about. And, no doubt, the supplying of -a proper amount of this tutorial, practical teaching, is a difficulty -in the way of giving proper instruction in Physical Science in such -Universities as that of Aberdeen, which are devoid of endowments; and, -unlike the English Universities, have no moral claim on the funds of -richly endowed bodies to supply their wants. - -Examination—thorough, searching examination—is an indispensable -accompaniment of teaching; but I am almost inclined to commit myself -to the very heterodox proposition that it is a necessary evil. I am a -very old Examiner, having, for some twenty years past, been occupied -with examinations on a considerable scale, of all sorts and conditions -of men, and women too,—from the boys and girls of elementary schools -to the candidates for Honours and Fellowships in the Universities. I -will not say that, in this case as in so many others, the adage, that -familiarity breeds contempt, holds good; but my admiration for the -existing system of examination and its products, does not wax warmer -as I see more of it. Examination, like fire, is a good servant, but a -bad master; and there seems to me to be some danger of its becoming our -master. I by no means stand alone in this opinion. Experienced friends -of mine do not hesitate to say that students whose career they watch, -appear to them to become deteriorated by the constant effort to pass -this or that examination, just as we hear of men’s brains becoming -affected by the daily necessity of catching a train. They work to pass, -not to know; and outraged Science takes her revenge. They do pass, -and they don’t know. I have passed sundry examinations in my time, not -without credit, and I confess I am ashamed to think how very little -real knowledge underlay the torrent of stuff which I was able to pour -out on paper. In fact, that which examination, as ordinarily conducted, -tests, is simply a man’s power of work under stimulus, and his capacity -for rapidly and clearly producing that which, for the time, he has got -into his mind. Now, these faculties are by no means to be despised. -They are of great value in practical life, and are the making of many -an advocate, and of many a so-called statesman. But in the pursuit of -truth, scientific or other, they count for very little, unless they are -supplemented by that long-continued, patient “intending of the mind,” -as Newton phrased it, which makes very little show in Examinations. I -imagine that an Examiner who knows his students personally, must not -unfrequently have found himself in the position of finding A’s paper -better than B’s, though his own judgment tells him, quite clearly, that -B is the man who has the larger share of genuine capacity. - -Again, there is a fallacy about Examiners. It is commonly supposed that -any one who knows a subject is competent to teach it; and no one seems -to doubt that any one who knows a subject is competent to examine in -it. I believe both these opinions to be serious mistakes: the latter, -perhaps, the more serious of the two. In the first place, I do not -believe that any one who is not, or has not been, a teacher is really -qualified to examine advanced students. And in the second place, -Examination is an Art, and a difficult one, which has to be learned -like all other arts. - -Beginners always set too difficult questions—partly because they are -afraid of being suspected of ignorance if they set easy ones, and -partly from not understanding their business. Suppose that you want to -test the relative physical strength of a score of young men. You do not -put a hundredweight down before them, and tell each to swing it round. -If you do, half of them won’t be able to lift it at all, and only one -or two will be able to perform the task. You must give them half a -hundredweight, and see how they manœuvre that, if you want to form any -estimate of the muscular strength of each. So, a practised Examiner -will seek for information respecting the mental vigour and training of -candidates from the way in which they deal with questions easy enough -to let reason, memory, and method have free play. - -No doubt, a great deal is to be done by the careful selection of -Examiners, and by the copious introduction of practical work, to -remove the evils inseparable from examination; but, under the best of -circumstances, I believe that examination will remain but an imperfect -test of knowledge, and a still more imperfect test of capacity, while -it tells next to nothing about a man’s power as an investigator. - -There is much to be said in favour of restricting the highest degrees -in each Faculty, to those who have shown evidence of such original -power, by prosecuting a research under the eye of the Professor in -whose province it lies; or, at any rate, under conditions which shall -afford satisfactory proof that the work is theirs. The notion may sound -revolutionary, but it is really very old; for, I take it, that it lies -at the bottom of that presentation of a thesis by the candidate for a -doctorate, which has now, too often, become little better than a matter -of form. - - -Thus far, I have endeavoured to lay before you, in a too brief and -imperfect manner, my views respecting the teaching half—the Magistri -and Regentes—of the University of the Future. Now let me turn to the -learning half—the Scholares. - -If the Universities are to be the sanctuaries of the highest culture of -the country, those who would enter that sanctuary, must not come with -unwashed hands. If the good seed is to yield its hundredfold harvest, -it must not be scattered amidst the stones of ignorance, or the tares -of undisciplined indolence and wantonness. On the contrary, the soil -must have been carefully prepared, and the Professor should find that -the operations of clod-crushing, draining, and weeding, and even a good -deal of planting, have been done by the Schoolmaster. - -That is exactly what the Professor does not find in any University in -the three Kingdoms that I can hear of—the reason of which state of -things lies in the extremely faulty organisation of the majority of -secondary Schools. Students come to the Universities ill-prepared in -classics and mathematics, not at all prepared in anything else; and -half their time is spent in learning that which they ought to have -known when they came. - -I sometimes hear it said that the Scottish Universities differ from -the English, in being to a much greater extent places of comparatively -elementary education for a younger class of students. But it would seem -doubtful if any great difference of this kind really exists; for a high -authority, himself Head of an English College, has solemnly affirmed -that: “Elementary teaching of youths under twenty is now the only -function performed by the University;” and that Colleges are “boarding -schools in which the elements of the learned languages are taught to -youths.”[6] - -This is not the first time that I have quoted those remarkable -assertions. I should like to engrave them in public view, for they -have not been refuted; and I am convinced that if their import is once -clearly apprehended, they will play no mean part when the question of -University reorganisation, with a view to practical measures, comes -on for discussion. You are not responsible for this anomalous state -of affairs now; but, as you pass into active life and acquire the -political influence to which your education and your position should -entitle you, you will become responsible for it, unless each in his -sphere does his best to alter it, by insisting on the improvement of -secondary Schools. - -Your present responsibility is of another, though not less serious, -kind. Institutions do not make men, any more than organisation makes -life; and even the ideal University we have been dreaming about will be -but a superior piece of mechanism, unless each student strive after the -ideal of the Scholar. And that ideal, it seems to me, has never been -better embodied than by the great Poet, who, though lapped in luxury, -the favourite of a Court, and the idol of his countrymen, remained -through all the length of his honoured years a Scholar in Art, in -Science, and in Life. - - “Would’st shape a noble life? Then cast - No backward glances towards the past: - And though somewhat be lost and gone, - Yet do thou act as one new-born. - What each day needs, that shalt thou ask; - Each day will set its proper task. - Give other’s work just share of praise; - Not of thine own the merits raise. - Beware no fellow man thou hate: - And so in God’s hands leave thy fate.”[7] - - - - -III. - -TECHNICAL EDUCATION. - - -Any candid observer of the phenomena of modern society will readily -admit that bores must be classed among the enemies of the human race; -and a little consideration will probably lead him to the further -admission, that no species of that extensive genus of noxious creatures -is more objectionable than the educational bore. Convinced as I am of -the truth of this great social generalisation, it is not without a -certain trepidation that I venture to address you on an educational -topic. For, in the course of the last ten years, to go back no farther, -I am afraid to say how often I have ventured to speak of education, -from that given in the primary schools to that which is to be had in -the universities and medical colleges; indeed, the only part of this -wide region into which, as yet, I have not adventured is that into -which I propose to intrude to-day. - -Thus, I cannot but be aware that I am dangerously near becoming the -thing which all men fear and fly. But I have deliberately elected to -run the risk. For when you did me the honour to ask me to address you, -an unexpected circumstance had led me to occupy myself seriously with -the question of technical education; and I had acquired the conviction -that there are few subjects respecting which it is more important for -all classes of the community to have clear and just ideas than this; -while, certainly, there is none which is more deserving of attention by -the Working Men’s Club and Institute Union. - -It is not for me to express an opinion whether the considerations, -which I am about to submit to you, will be proved by experience to be -just or not; but I will do my best to make them clear. Among the many -good things to be found in Lord Bacon’s works, none is more full of -wisdom than the saying that “truth more easily comes out of error than -out of confusion.” Clear and consecutive wrong-thinking is the next -best thing to right-thinking; so that, if I succeed in clearing your -ideas on this topic, I shall have wasted neither your time nor my own. - -“Technical education,” in the sense in which the term is ordinarily -used, and in which I am now employing it, means that sort of education -which is specially adapted to the needs of men whose business in -life it is to pursue some kind of handicraft; it is, in fact, a fine -Greco-Latin equivalent for what in good vernacular English would be -called “the teaching of handicrafts.” And probably, at this stage of -our progress, it may occur to many of you to think of the story of the -cobbler and his last, and to say to yourselves, though you will be too -polite to put the question openly to me, What does the speaker know -practically about this matter? What is his handicraft? I think the -question is a very proper one, and unless I were prepared to answer it, -I hope satisfactorily, I should have chosen some other theme. - -The fact is, I am, and have been, any time these thirty years, a man -who works with his hands—a handicraftsman. I do not say this in the -broadly metaphorical sense in which fine gentlemen, with all the -delicacy of Agag about them, trip to the hustings about election time, -and protest that they too are working men. I really mean my words to be -taken in their direct, literal, and straightforward sense. In fact, if -the most nimble-fingered watchmaker among you will come to my workshop, -he may set me to put a watch together, and I will set him to dissect, -say, a blackbeetle’s nerves. I do not wish to vaunt, but I am inclined -to think that I shall manage my job to his satisfaction sooner than he -will do his piece of work to mine. - -In truth, anatomy, which is my handicraft, is one of the most difficult -kinds of mechanical labour, involving, as it does, not only lightness -and dexterity of hand, but sharp eyes and endless patience. And you -must not suppose that my particular branch of science is especially -distinguished for the demand it makes upon skill in manipulation. A -similar requirement is made upon all students of physical science. -The astronomer, the electrician, the chemist, the mineralogist, the -botanist, are constantly called upon to perform manual operations of -exceeding delicacy. The progress of all branches of physical science -depends upon observation, or on that artificial observation which is -termed experiment, of one kind or another; and, the farther we advance, -the more practical difficulties surround the investigation of the -conditions of the problems offered to us; so that mobile and yet steady -hands, guided by clear vision, are more and more in request in the -workshops of science. - -Indeed, it has struck me that one of the grounds of that sympathy -between the handicraftsmen of this country and the men of science, by -which it has so often been my good fortune to profit, may, perhaps, lie -here. You feel and we feel that, among the so-called learned folks, we -alone are brought into contact with tangible facts in the way that you -are. You know well enough that it is one thing to write a history of -chairs in general, or to address a poem to a throne, or to speculate -about the occult powers of the chair of St. Peter; and quite another -thing to make with your own hands a veritable chair, that will stand -fair and square, and afford a safe and satisfactory resting-place to a -frame of sensitiveness and solidity. - -So it is with us, when we look out from our scientific handicrafts -upon the doings of our learned brethren, whose work is untrammelled -by anything “base and mechanical,” as handicrafts used to be called -when the world was younger, and, in some respects, less wise than -now. We take the greatest interest in their pursuits; we are edified -by their histories and are charmed with their poems, which sometimes -illustrate so remarkably the powers of man’s imagination; some of us -admire and even humbly try to follow them in their high philosophical -excursions, though we know the risk of being snubbed by the inquiry -whether grovelling dissectors of monkeys and blackbeetles can hope -to enter into the empyreal kingdom of speculation. But still we feel -that our business is different; humbler if you will, though the -diminution of dignity is, perhaps, compensated by the increase of -reality; and that we, like you, have to get our work done in a region -where little avails, if the power of dealing with practical tangible -facts is wanting. You know that clever talk touching joinery will not -make a chair; and I know that it is of about as much value in the -physical sciences. Mother Nature is serenely obdurate to honeyed words; -only those who understand the ways of things, and can silently and -effectually handle them, get any good out of her. - - -And now, having, as I hope, justified my assumption of a place among -handicraftsmen, and put myself right with you as to my qualification, -from practical knowledge, to speak about technical education, I will -proceed to lay before you the results of my experience as a teacher of -a handicraft, and tell you what sort of education I should think best -adapted for a boy whom one wanted to make a professional anatomist. - -I should say, in the first place, let him have a good English -elementary education. I do not mean that he shall be able to pass -in such and such a standard—that may or may not be an equivalent -expression—but that his teaching shall have been such as to have given -him command of the common implements of learning and to have created a -desire for the things of the understanding. - -Further, I should like him to know the elements of physical science, -and especially of physics and chemistry, and I should take care that -this elementary knowledge was real. I should like my aspirant to -be able to read a scientific treatise in Latin, French, or German, -because an enormous amount of anatomical knowledge is locked up in -those languages. And especially, I should require some ability to -draw—I do not mean artistically, for that is a gift which may be -cultivated but cannot be learned, but with fair accuracy. I will not -say that everybody can learn even this; for the negative development -of the faculty of drawing in some people is almost miraculous. Still -everybody, or almost everybody, can learn to write; and, as writing is -a kind of drawing, I suppose that the majority of the people who say -they cannot draw, and give copious evidence of the accuracy of their -assertion, could draw, after a fashion, if they tried. And that “after -a fashion” would be better than nothing for my purposes. - -Above all things, let my imaginary pupil have preserved the freshness -and vigour of youth in his mind as well as his body. The educational -abomination of desolation of the present day is the stimulation -of young people to work at high pressure by incessant competitive -examinations. Some wise man (who probably was not an early riser) -has said of early risers in general, that they are conceited all the -forenoon and stupid all the afternoon. Now whether this is true of -early risers in the common acceptation of the word or not, I will not -pretend to say; but it is too often true of the unhappy children who -are forced to rise too early in their classes. They are conceited all -the forenoon of life, and stupid all its afternoon. The vigour and -freshness, which should have been stored up for the purposes of the -hard struggle for existence in practical life, have been washed out -of them by precocious mental debauchery—by book gluttony and lesson -bibbing. Their faculties are worn out by the strain put upon their -callow brains, and they are demoralised by worthless childish triumphs -before the real work of life begins. I have no compassion for sloth, -but youth has more need for intellectual rest than age; and the -cheerfulness, the tenacity of purpose, the power of work which make -many a successful man what he is, must often be placed to the credit, -not of his hours of industry, but to that of his hours of idleness, -in boyhood. Even the hardest worker of us all, if he has to deal with -anything above mere details, will do well, now and again, to let his -brain lie fallow for a space. The next crop of thought will certainly -be all the fuller in the ear and the weeds fewer. - -This is the sort of education which I should like any one who was -going to devote himself to my handicraft to undergo. As to knowing -anything about anatomy itself, on the whole I would rather he left that -alone until he took it up seriously in my laboratory. It is hard work -enough to teach, and I should not like to have superadded to that the -possible need of unteaching. - -Well, but, you will say, this is Hamlet with the Prince of Denmark left -out; your “technical education” is simply a good education, with more -attention to physical science, to drawing, and to modern languages, -than is common, and there is nothing specially technical about it. - -Exactly so; that remark takes us straight to the heart of what I have -to say; which is, that, in my judgment, the preparatory education -of the handicraftsman ought to have nothing of what is ordinarily -understood by “technical” about it. - -The workshop is the only real school for a handicraft. The education -which precedes that of the workshop should be entirely devoted to the -strengthening of the body, the elevation of the moral faculties, and -the cultivation of the intelligence; and, especially, to the imbuing -the mind with a broad and clear view of the laws of that natural world -with the components of which the handicraftsman will have to deal. And, -the earlier the period of life at which the handicraftsman has to enter -into actual practice of his craft, the more important is it that he -should devote the precious hours of preliminary education to things of -the mind, which have no direct and immediate bearing on his branch of -industry, though they lie at the foundation of all realities. - - -Now let me apply the lessons I have learned from my handicraft to -yours. If any of you were obliged to take an apprentice, I suppose -you would like to get a good healthy lad, ready and willing to learn, -handy, and with his fingers not all thumbs, as the saying goes. You -would like that he should read, write, and cipher well; and, if you -were an intelligent master, and your trade involved the application of -scientific principles, as so many trades do, you would like him to know -enough of the elementary principles of science to understand what was -going on. I suppose that, in nine trades out of ten, it would be useful -if he could draw; and many of you must have lamented your inability -to find out for yourselves what foreigners are doing or have done. So -that some knowledge of French and German might, in many cases, be very -desirable. - -So it appears to me that what you want is pretty much what I want; and -the practical question is, How you are to get what you need, under the -actual limitations and conditions of life of handicraftsmen in this -country? - -I think I shall have the assent both of the employers of labour and of -the employed as to one of these limitations; which is, that no scheme -of technical education is likely to be seriously entertained which will -delay the entrance of boys into working life, or prevent them from -contributing towards their own support, as early as they do at present. -Not only do I believe that any such scheme could not be carried out, -but I doubt its desirableness, even if it were practicable. - -The period between childhood and manhood is full of difficulties and -dangers, under the most favourable circumstances; and, even among the -well-to-do, who can afford to surround their children with the most -favourable conditions, examples of a career ruined, before it has well -begun, are but too frequent. Moreover, those who have to live by labour -must be shaped to labour early. The colt that is left at grass too -long makes but a sorry draught-horse, though his way of life does not -bring him within the reach of artificial temptations. Perhaps the most -valuable result of all education is the ability to make yourself do the -thing you have to do, when it ought to be done, whether you like it -or not; it is the first lesson that ought to be learned; and, however -early a man’s training begins, it is probably the last lesson that he -learns thoroughly. - -There is another reason, to which I have already adverted, and which -I would reiterate, why any extension of the time devoted to ordinary -school-work is undesirable. In the newly awakened zeal for education, -we run some risk of forgetting the truth that while under-instruction -is a bad thing, over-instruction may possibly be a worse. - -Success in any kind of practical life is not dependent solely, or -indeed chiefly, upon knowledge. Even in the learned professions, -knowledge, alone, is of less consequence than people are apt to -suppose. And, if much expenditure of bodily energy is involved in the -day’s work, mere knowledge is of still less importance when weighed -against the probable cost of its acquirement. To do a fair day’s work -with his hands, a man needs, above all things, health, strength, and -the patience and cheerfulness which, if they do not always accompany -these blessings, can hardly in the nature of things exist without them; -to which we must add honesty of purpose and a pride in doing what is -done well. - -A good handicraftsman can get on very well without genius, but he will -fare badly without a reasonable share of that which is a more useful -possession for workaday life, namely, mother-wit; and he will be all -the better for a real knowledge, however limited, of the ordinary laws -of nature, and especially of those which apply to his own business. - -Instruction carried so far as to help the scholar to turn his store of -mother-wit to account, to acquire a fair amount of sound elementary -knowledge, and to use his hands and eyes; while leaving him fresh, -vigorous, and with a sense of the dignity of his own calling, whatever -it may be, if fairly and honestly pursued, cannot fail to be of -invaluable service to all those who come under its influence. - -But, on the other hand, if school instruction is carried so far as to -encourage bookishness; if the ambition of the scholar is directed, not -to the gaining of knowledge, but to the being able to pass examinations -successfully; especially if encouragement is given to the mischievous -delusion that brainwork is, in itself, and apart from its quality, a -nobler or more respectable thing than handiwork—such education may be -a deadly mischief to the workman, and lead to the rapid ruin of the -industries it is intended to serve. - -I know that I am expressing the opinion of some of the largest as well -as the most enlightened employers of labour, when I say that there is -a real danger that, from the extreme of no education, we may run to -the other extreme of over-education of handicraftsmen. And I apprehend -that what is true for the ordinary hand-worker is true for the foreman. -Activity, probity, knowledge of men, ready mother-wit, supplemented by -a good knowledge of the general principles involved in his business, -are the making of a good foreman. If he possess these qualities, no -amount of learning will fit him better for his position; while the -course of life and the habit of mind required for the attainment of -such learning may, in various direct and indirect ways, act as direct -disqualifications for it. - -Keeping in mind, then, that the two things to be avoided are, the delay -of the entrance of boys into practical life, and the substitution -of exhausted book-worms for shrewd, handy men, in our works and -factories, let us consider what may be wisely and safely attempted in -the way of improving the education of the handicraftsman. - -First, I look to the elementary schools now happily established all -over the country. I am not going to criticise or find fault with -them; on the contrary, their establishment seems to me to be the most -important and the most beneficial result of the corporate action of the -people in our day. A great deal is said of British interests just now, -but, depend upon it, that no Eastern difficulty needs our intervention -as a nation so seriously, as the putting down both the Bashi-Bazouks -of ignorance and the Cossacks of sectarianism at home. What has already -been achieved in these directions is a great thing; you must have lived -some time to know how great. An education, better in its processes, -better in its substance, than that which was accessible to the great -majority of well-to-do Britons a quarter of a century ago, is now -obtainable by every child in the land. Let any man of my age go into -an ordinary elementary school, and, unless he was unusually fortunate -in his youth, he will tell you that the educational method, the -intelligence, patience, and good temper on the teacher’s part, which -are now at the disposal of the veriest waifs and wastrels of society, -are things of which he had no experience in those costly middle-class -schools, which were so ingeniously contrived as to combine all the -evils and shortcomings of the great public schools with none of their -advantages. Many a man, whose so-called education cost a good deal of -valuable money and occupied many a year of invaluable time, leaves the -inspection of a well-ordered elementary school devoutly wishing that, -in his young days, he had had the chance of being as well taught as -these boys and girls are. - -But while, in view of such an advance in general education, I willingly -obey the natural impulse to be thankful, I am not willing altogether -to rest. I want to see instruction in elementary science and in art -more thoroughly incorporated in the educational system. At present, it -is being administered by driblets, as if it were a potent medicine, -“a few drops to be taken occasionally in a teaspoon.” Every year I -notice that that earnest and untiring friend of yours and of mine, -Sir John Lubbock, stirs up the Government of the day in the House of -Commons on this subject; and also that, every year, he, and the few -members of the House of Commons, such as Mr. Playfair, who sympathise -with him, are met with expressions of warm admiration for science in -general, and reasons at large for doing nothing in particular. But now -that Mr. Forster, to whom the education of the country owes so much, -has announced his conversion to the right faith, I begin to hope that, -sooner or later, things will mend. - -I have given what I believe to be a good reason for the assumption, -that the keeping at school of boys, who are to be handicraftsmen, -beyond the age of thirteen or fourteen is neither practicable nor -desirable; and, as it is quite certain, that, with justice to other -and no less important branches of education, nothing more than the -rudiments of science and art teaching can be introduced into elementary -schools, we must seek elsewhere for a supplementary training in these -subjects, and, if need be, in foreign languages, which may go on after -the workman’s life has begun. - -The means of acquiring the scientific and artistic part of this -training already exists in full working order, in the first place, in -the classes of the Science and Art Department, which are, for the most -part, held in the evening, so as to be accessible to all who choose to -avail themselves of them after working hours. The great advantage of -these classes is that they bring the means of instruction to the doors -of the factories and workshops; that they are no artificial creations, -but by their very existence prove the desire of the people for them; -and finally, that they admit of indefinite development in proportion -as they are wanted. I have often expressed the opinion, and I repeat -it here, that, during the eighteen years they have been in existence, -these classes have done incalculable good; and I can say, of my own -knowledge, that the Department spares no pains and trouble in trying to -increase their usefulness and ensure the soundness of their work. - -No one knows better than my friend Colonel Donnelly, to whose clear -views and great administrative abilities so much of the successful -working of the science classes is due, that there is much to be done -before the system can be said to be thoroughly satisfactory. The -instruction given needs to be made more systematic and especially more -practical; the teachers are of very unequal excellence, and not a few -stand much in need of instruction themselves, not only in the subjects -which they teach, but in the objects for which they teach. I daresay -you have heard of that proceeding, reprobated by all true sportsmen, -which is called “shooting for the pot.” Well, there is such a thing -as “teaching for the pot”—teaching, that is, not that your scholar -may know, but that he may count for payment among those who pass the -examination; and there are some teachers, happily not many, who have -yet to learn that the examiners of the Department regard them as -poachers of the worst description. - -Without presuming in any way to speak in the name of the Department, I -think I may say, as a matter which has come under my own observation, -that it is doing its best to meet all these difficulties. It -systematically promotes practical instruction in the classes; it -affords facilities to teachers who desire to learn their business -thoroughly; and it is always ready to aid in the suppression of -pot-teaching. - -All this is, as you may imagine, highly satisfactory to me. I see that -spread of scientific education, about which I have so often permitted -myself to worry the public, become, for all practical purposes, an -accomplished fact. Grateful as I am for all that is now being done, -in the same direction, in our higher schools and universities, I have -ceased to have any anxiety about the wealthier classes. Scientific -knowledge is spreading by what the alchemists called a “distillatio per -ascensum;” and nothing now can prevent it from continuing to distil -upwards and permeate English society, until, in the remote future, -there shall be no member of the legislature who does not know as much -of science as an elementary school-boy; and even the heads of houses -in our venerable seats of learning shall acknowledge that natural -science is not merely a sort of University back-door through which -inferior men may get at their degrees. Perhaps this apocalyptic vision -is a little wild; and I feel I ought to ask pardon for an outbreak of -enthusiasm, which, I assure you, is not my commonest failing. I have -said that the Government is already doing a great deal in aid of that -kind of technical education for handicraftsmen which, to my mind, is -alone worth seeking. Perhaps it is doing as much as it ought to do, -even in this direction. Certainly there is another kind of help of the -most important character, for which we may look elsewhere than to the -Government. The great mass of mankind have neither the liking, nor the -aptitude, for either literary, or scientific, or artistic pursuits; -nor, indeed, for excellence of any sort. Their ambition is to go -through life with moderate exertion and a fair share of ease, doing -common things in a common way. And a great blessing and comfort it is -that the majority of men are of this mind; for the majority of things -to be done are common things, and are quite well enough done when -commonly done. The great end of life is not knowledge but action. What -men need is, as much knowledge as they can assimilate and organise into -a basis for action; give them more and it may become injurious. One -knows people who are as heavy and stupid from undigested learning as -others are from over-fulness of meat and drink. But a small percentage -of the population is born with that most excellent quality, a desire -for excellence, or with special aptitudes of some sort or another; Mr. -Galton tells us that not more than one in four thousand may be expected -to attain distinction, and not more than one in a million some share -of that intensity of instinctive aptitude, that burning thirst for -excellence, which is called genius. - -Now, the most important object of all educational schemes is to -catch these exceptional people, and turn them to account for the -good of society. No man can say where they will crop up; like their -opposites, the fools and knaves, they appear sometimes in the palace, -and sometimes in the hovel; but the great thing to be aimed at, I was -almost going to say the most important end of all social arrangements, -is to keep these glorious sports of Nature from being either corrupted -by luxury or starved by poverty, and to put them into the position in -which they can do the work for which they are specially fitted. - -Thus, if a lad in an elementary school showed signs of special -capacity, I would try to provide him with the means of continuing his -education after his daily working life had begun; if, in the evening -classes, he developed special capabilities in the direction of science -or of drawing, I would try to secure him an apprenticeship to some -trade in which those powers would have applicability. Or, if he chose -to become a teacher, he should have the chance of so doing. Finally, to -the lad of genius, the one in a million, I would make accessible the -highest and most complete training the country could afford. Whatever -that might cost, depend upon it the investment would be a good one. I -weigh my words when I say that if the nation could purchase a potential -Watt, or Davy, or Faraday, at the cost of a hundred thousand pounds -down, he would be dirt-cheap at the money. It is a mere commonplace -and everyday piece of knowledge, that what these three men did has -produced untold millions of wealth, in the narrowest economical sense -of the word. - -Therefore, as the sum and crown of what is to be done for technical -education, I look to the provision of a machinery for winnowing out the -capacities and giving them scope. When I was a member of the London -School Board, I said, in the course of a speech, that our business -was to provide a ladder, reaching from the gutter to the university, -along which every child in the three kingdoms should have the chance of -climbing as far as he was fit to go. This phrase was so much bandied -about at the time, that, to say truth, I am rather tired of it; but I -know of no other which so fully expresses my belief, not only about -education in general, but about technical education in particular. - -The essential foundation of all the organisation needed for the -promotion of education among handicraftsmen will, I believe, exist in -this country, when every working lad can feel that society has done -as much as lies in its power to remove all needless and artificial -obstacles from his path; that there is no barrier, except such as -exists in the nature of things, between himself and whatever place in -the social organisation he is fitted to fill; and, more than this, -that, if he has capacity and industry, a hand is held out to help him -along any path which is wisely and honestly chosen. - -I have endeavoured to point out to you that a great deal of such an -organisation already exists; and I am glad to be able to add that -there is a good prospect that what is wanting will, before long, be -supplemented. - -Those powerful and wealthy societies, the livery companies of the City -of London, remembering that they are the heirs and representatives of -the trade guilds of the Middle Ages, are interesting themselves in the -question. So far back as 1872 the Society of Arts organised a system -of instruction in the technology of arts and manufactures, for persons -actually employed in factories and workshops, who desired to extend and -improve their knowledge of the theory and practice of their particular -avocations;[8] and a considerable subsidy, in aid of the efforts of -the Society, was liberally granted by the Clothworkers’ Company. We -have here the hopeful commencement of a rational organisation for the -promotion of excellence among handicraftsmen. Quite recently, other of -the livery companies have determined upon giving their powerful, and, -indeed, almost boundless, aid to the improvement of the teaching of -handicrafts. They have already gone so far as to appoint a committee -to act for them; and I betray no confidence in adding that, some time -since, the committee sought the advice and assistance of several -persons, myself among the number. - -Of course I cannot tell you what may be the result of the deliberations -of the committee; but we may all fairly hope that, before long, steps -which will have a weighty and a lasting influence on the growth and -spread of sound and thorough teaching among the handicraftsmen[9] of -this country will be taken by the livery companies of London. - - [This hope has been fully justified by the establishment - of the Cowper Street Schools, and that of the Central - Institution of the City and Guilds of London Institute. - September 1881.] - - - - -IV. - -ON ELEMENTARY INSTRUCTION IN PHYSIOLOGY. - - -The chief ground upon which I venture to recommend that the teaching of -elementary physiology should form an essential part of any organised -course of instruction in matters pertaining to domestic economy, is, -that a knowledge of even the elements of this subject supplies those -conceptions of the constitution and mode of action of the living body, -and of the nature of health and disease, which prepare the mind to -receive instruction from sanitary science. - -It is, I think, eminently desirable that the hygienist and the -physician should find something in the public mind to which they can -appeal; some little stock of universally acknowledged truths, which may -serve as a foundation for their warnings, and predispose towards an -intelligent obedience to their recommendations. - -Listening to ordinary talk about health, disease, and death, one is -often led to entertain a doubt whether the speakers believe that the -course of natural causation runs as smoothly in the human body as -elsewhere. Indications are too often obvious of a strong, though -perhaps an unavowed and half unconscious, under-current of opinion -that the phenomena of life are not only widely different, in their -superficial characters and in their practical importance, from other -natural events, but that they do not follow in that definite order -which characterises the succession of all other occurrences, and the -statement of which we call a law of nature. - -Hence, I think, arises the want of heartiness of belief in the value -of knowledge respecting the laws of health and disease, and of the -foresight and care to which knowledge is the essential preliminary, -which is so often noticeable; and a corresponding laxity and -carelessness in practice, the results of which are too frequently -lamentable. - -It is said that among the many religious sects of Russia, there is one -which holds that all disease is brought about by the direct and special -interference of the Deity, and which, therefore, looks with repugnance -upon both preventive and curative measures as alike blasphemous -interferences with the will of God. Among ourselves, the “Peculiar -People” are, I believe, the only persons who hold the like doctrine -in its integrity, and carry it out with logical rigour. But many of -us are old enough to recollect that the administration of chloroform -in assuagement of the pangs of childbirth was, at its introduction, -strenuously resisted upon similar grounds. - -I am not sure that the feeling, of which the doctrine to which I have -referred is the full expression, does not lie at the bottom of the -minds of a great many people who yet would vigorously object to give -a verbal assent to the doctrine itself. However this may be, the main -point is that sufficient knowledge has now been acquired of vital -phenomena, to justify the assertion, that the notion, that there is -anything exceptional about these phenomena, receives not a particle of -support from any known fact. On the contrary, there is a vast and an -increasing mass of evidence that birth and death, health and disease, -are as much parts of the ordinary stream of events as the rising and -setting of the sun, or the changes of the moon; and that the living -body is a mechanism, the proper working of which we term health; -its disturbance, disease; its stoppage, death. The activity of this -mechanism is dependent upon many and complicated conditions, some of -which are hopelessly beyond our control, while others are readily -accessible, and are capable of being indefinitely modified by our own -actions. The business of the hygienist and of the physician is to know -the range of these modifiable conditions, and how to influence them -towards the maintenance of health and the prolongation of life; the -business of the general public is to give an intelligent assent, and -a ready obedience based upon that assent, to the rules laid down for -their guidance by such experts. But an intelligent assent is an assent -based upon knowledge, and the knowledge which is here in question means -an acquaintance with the elements of physiology. - -It is not difficult to acquire such knowledge. What is true, to -a certain extent, of all the physical sciences, is eminently -characteristic of physiology—the difficulty of the subject begins -beyond the stage of elementary knowledge, and increases with every -stage of progress. While the most highly trained and the best furnished -intellect may find all its resources insufficient, when it strives to -reach the heights and penetrate into the depths of the problems of -physiology, the elementary and fundamental truths can be made clear to -a child. - -No one can have any difficulty in comprehending the mechanism of -circulation or respiration; or the general mode of operation of the -organ of vision; though the unravelling of all the minutiæ of these -processes, may, for the present, baffle the conjoined attacks of -the most accomplished physicists, chemists, and mathematicians. To -know the anatomy of the human body, with even an approximation to -thoroughness, is the work of a life; but as much as is needed for a -sound comprehension of elementary physiological truths, may be learned -in a week. - -A knowledge of the elements of physiology is not only easy of -acquirement, but it may be made a real and practical acquaintance -with the facts, as far as it goes. The subject of study is always at -hand, in oneself. The principal constituents of the skeleton, and the -changes of form of contracting muscles, may be felt through one’s -own skin. The beating of one’s heart, and its connection with the -pulse, may be noted; the influence of the valves of one’s own veins -may be shown; the movements of respiration may be observed; while the -wonderful phenomena of sensation afford an endless field for curious -and interesting self-study. The prick of a needle will yield, in a drop -of one’s own blood, material for microscopic observation of phenomena -which lie at the foundation of all biological conceptions; and a cold, -with its concomitant coughing and sneezing, may prove the sweet uses -of adversity by helping one to a clear conception of what is meant by -“reflex action.” - -Of course there is a limit to this physiological self-examination. -But there is so close a solidarity between ourselves and our poor -relations of the animal world, that our inaccessible inward parts -may be supplemented by theirs. A comparative anatomist knows that a -sheep’s heart and lungs, or eye, must not be confounded with those of -a man; but, so far as the comprehension of the elementary facts of the -physiology of circulation, of respiration, and of vision goes, the one -furnishes the needful anatomical data as well as the other. - -Thus, it is quite possible to give instruction in elementary physiology -in such a manner as, not only to confer knowledge, which, for the -reason I have mentioned, is useful in itself; but to serve the purposes -of a training in accurate observation, and in the methods of reasoning -of physical science. But that is an advantage which I mention only -incidentally, as the present Conference does not deal with education in -the ordinary sense of the word. - -It will not be suspected that I wish to make physiologists of all the -world. It would be as reasonable to accuse an advocate of the “three -R’s” of a desire to make an orator, an author, and a mathematician of -everybody. A stumbling reader, a pot-hook writer, and an arithmetician -who has not got beyond the rule of three, is not a person of brilliant -acquirements; but the difference between such a member of society and -one who can neither read, write, nor cipher is almost inexpressible; -and no one now-a-days doubts the value of instruction, even if it goes -no farther. - -The saying that a little knowledge is a dangerous thing is, to my -mind, a very dangerous adage. If knowledge is real and genuine, I do -not believe that it is other than a very valuable possession, however -infinitesimal its quantity may be. Indeed, if a little knowledge is -dangerous, where is the man who has so much as to be out of danger? - -If William Harvey’s life-long labours had revealed to him a tenth -part of that which may be made sound and real knowledge to our boys -and girls, he would not only have been what he was, the greatest -physiologist of his age, but he would have loomed upon the seventeenth -century as a sort of intellectual portent. Our “little knowledge” would -have been to him a great, astounding, unlooked-for vision of scientific -truth. - -I really see no harm which can come of giving our children a little -knowledge of physiology. But then, as I have said, the instruction -must be real, based upon observation, eked out by good explanatory -diagrams and models, and conveyed by a teacher whose own knowledge has -been acquired by a study of the facts; and not the mere catechismal -parrot-work which too often usurps the place of elementary teaching. - -It is, I hope, unnecessary for me to give a formal contradiction to -the silly fiction, which is assiduously circulated by fanatics who not -only ought to know, but do know, that their assertions are untrue, -that I have advocated the introduction of that experimental discipline -which is absolutely indispensable to the professed physiologist, into -elementary teaching. - -But while I should object to any experimentation which can justly be -called painful, for the purpose of elementary instruction; and, while, -as a member of a late Royal Commission, I gladly did my best to prevent -the infliction of needless pain, for any purpose; I think it is my duty -to take this opportunity of expressing my regret at a condition of the -law which permits a boy to troll for pike, or set lines with live frog -bait, for idle amusement; and, at the same time, lays the teacher of -that boy open to the penalty of fine and imprisonment, if he uses the -same animal for the purpose of exhibiting one of the most beautiful -and instructive of physiological spectacles, the circulation in the -web of the foot. No one could undertake to affirm that a frog is not -inconvenienced by being wrapped up in a wet rag, and having his toes -tied out; and it cannot be denied that inconvenience is a sort of pain. -But you must not inflict the least pain on a vertebrated animal for -scientific purposes (though you may do a good deal in that way for gain -or for sport) without due licence of the Secretary of State for the -Home Department, granted under the authority of the Vivisection Act. - -So it comes about, that, in this present year of grace 1877, two -persons may be charged with cruelty to animals. One has impaled a frog, -and suffered the creature to writhe about in that condition for hours; -the other has pained the animal no more than one of us would be pained -by tying strings round his fingers, and keeping him in the position -of a hydropathic patient. The first offender says, “I did it because -I find fishing very amusing,” and the magistrate bids him depart in -peace; nay, probably wishes him good sport. The second pleads, “I -wanted to impress a scientific truth, with a distinctness attainable in -no other way, on the minds of my scholars,” and the magistrate fines -him five pounds. - -I cannot but think that this is an anomalous and not wholly creditable -state of things. - - - - -V. - -JOSEPH PRIESTLEY. - - -If the man to perpetuate whose memory we have this day raised a -statue had been asked on what part of his busy life’s work he set the -highest value, he would undoubtedly have pointed to his voluminous -contributions to theology. In season and out of season, he was the -steadfast champion of that hypothesis respecting the Divine nature -which is termed Unitarianism by its friends and Socinianism by its -foes. Regardless of odds, he was ready to do battle with all comers in -that cause; and if no adversaries entered the lists, he would sally -forth to seek them. - -To this, his highest ideal of duty, Joseph Priestley sacrificed the -vulgar prizes of life, which, assuredly, were within easy reach of a -man of his singular energy and varied abilities. For this object, he -put aside, as of secondary importance, those scientific investigations -which he loved so well, and in which he showed himself so competent -to enlarge the boundaries of natural knowledge and to win fame. In -this cause, he not only cheerfully suffered obloquy from the bigoted -and the unthinking, and came within sight of martyrdom; but bore with -that which is much harder to be borne than all these, the unfeigned -astonishment and hardly disguised contempt of a brilliant society, -composed of men whose sympathy and esteem must have been most dear to -him, and to whom it was simply incomprehensible that a philosopher -should seriously occupy himself with any form of Christianity. - -It appears to me that the man who, setting before himself such an ideal -of life, acted up to it consistently, is worthy of the deepest respect, -whatever opinion may be entertained as to the real value of the tenets -which he so zealously propagated and defended. - -But I am sure that I speak not only for myself, but for all this -assemblage, when I say that our purpose to-day is to do honour, not -to Priestley, the Unitarian divine, but to Priestley, the fearless -defender of rational freedom in thought and in action: to Priestley, -the philosophic thinker; to that Priestley who held a foremost place -among “the swift runners who hand over the lamp of life,”[10] and -transmit from one generation to another the fire kindled, in the -childhood of the world, at the Promethean altar of Science. - - -The main incidents of Priestley’s life are so well known that I need -dwell upon them at no great length. - -Born in 1733, at Fieldhead, near Leeds, and brought up among Calvinists -of the straitest orthodoxy, the boy’s striking natural ability led to -his being devoted to the profession of a minister of religion; and, in -1752, he was sent to the Dissenting Academy at Daventry—an institution -which authority left undisturbed, though its existence contravened the -law. The teachers under whose instruction and influence the young man -came at Daventry, carried out to the letter the injunction to “try all -things: hold fast that which is good,” and encouraged the discussion -of every imaginable proposition with complete freedom, the leading -professors taking opposite sides; a discipline which, admirable as -it may be from a purely scientific point of view, would seem to be -calculated to make acute, rather than sound, divines. Priestley tells -us, in his “Autobiography,” that he generally found himself on the -unorthodox side: and, as he grew older, and his faculties attained -their maturity, this native tendency towards heterodoxy grew with his -growth and strengthened with his strength. He passed from Calvinism to -Arianism; and finally, in middle life, landed in that very broad form -of Unitarianism, by which his craving after a credible and consistent -theory of things was satisfied. - -On leaving Daventry, Priestley became minister of a congregation, first -at Needham Market, and secondly at Nantwich; but whether on account -of his heterodox opinions, or of the stuttering which impeded his -expression of them in the pulpit, little success attended his efforts -in this capacity. In 1761, a career much more suited to his abilities -became open to him. He was appointed “tutor in the languages” in the -Dissenting Academy at Warrington, in which capacity, besides giving -three courses of lectures, he taught Latin, Greek, French, and Italian, -and read lectures on the Theory of Language and Universal Grammar, on -Oratory, Philosophical Criticism, and Civil law. And it is interesting -to observe that, as a teacher, he encouraged and cherished in those -whom he instructed, the freedom which he had enjoyed, in his own -student days, at Daventry. One of his pupils tells us that, - - “At the conclusion of his lecture, he always encouraged - his students to express their sentiments relative to the - subject of it, and to urge any objections to what he had - delivered, without reserve. It pleased him when any one - commenced such a conversation. In order to excite the - freest discussion, he occasionally invited the students - to drink tea with him, in order to canvass the subjects - of his lectures. I do not recollect that he ever showed - the least displeasure at the strongest objections that - were made to what he delivered, but I distinctly remember - the smile of approbation with which he usually received - them: nor did he fail to point out, in a very encouraging - manner, the ingenuity or force of any remarks that were - made, when they merited these characters. His object, - as well as Dr. Aikin’s, was to engage the students to - examine and decide for themselves, uninfluenced by the - sentiments of any other persons.”[11] - -It would be difficult to give a better description of a model teacher -than that conveyed in these words. - -From his earliest days, Priestley had shown a strong bent towards the -study of nature; and his brother Timothy tells us that the boy put -spiders into bottles, to see how long they would live in the same air—a -curious anticipation of the investigations of his later years. At -Nantwich, where he set up a school, Priestley informs us that he bought -an air pump, an electrical machine, and other instruments, in the use -of which he instructed his scholars. But he does not seem to have -devoted himself seriously to physical science until 1766, when he had -the great good fortune to meet Benjamin Franklin, whose friendship he -ever afterwards enjoyed. Encouraged by Franklin, he wrote a “History of -Electricity,” which was published in 1767, and appears to have met with -considerable success. - -In the same year, Priestley left Warrington to become the minister of -a congregation at Leeds; and, here, happening to live next door to a -public brewery, as he says, - - “I, at first, amused myself with making experiments on - the fixed air which I found ready-made in the process - of fermentation. When I removed from that house I was - under the necessity of making fixed air for myself; and - one experiment leading to another, as I have distinctly - and faithfully noted in my various publications on the - subject, I by degrees contrived a convenient apparatus - for the purpose, but of the cheapest kind. - - “When I began these experiments I knew very little - of _chemistry_, and had, in a manner, no idea on the - subject before I attended a course of chemical lectures, - delivered in the Academy at Warrington, by Dr. Turner of - Liverpool. But I have often thought that, upon the whole, - this circumstance was no disadvantage to me; as, in this - situation, I was led to devise an apparatus and processes - of my own, adapted to my peculiar views; whereas, if I - had been previously accustomed to the usual chemical - processes, I should not have so easily thought of any - other, and without new modes of operation, I should - hardly have discovered anything materially new.”[12] - -The first outcome of Priestley’s chemical work, published in 1772, was -of a very practical character. He discovered the way of impregnating -water with an excess of “fixed air,” or carbonic acid, and thereby -producing what we now know as “soda water”—a service to naturally, -and still more to artificially, thirsty souls, which those whose -parched throats and hot heads are cooled by morning draughts of -that beverage, cannot too gratefully acknowledge. In the same year, -Priestley communicated the extensive series of observations which his -industry and ingenuity had accumulated, in the course of four years, -to the Royal Society, under the title of “Observations on Different -Kinds of Air”—a memoir which was justly regarded of so much merit and -importance, that the Society at once conferred upon the author the -highest distinction in their power, by awarding him the Copley Medal. - -In 1771 a proposal was made to Priestley to accompany Captain Cook -in his second voyage to the South Seas. He accepted it, and his -congregation agreed to pay an assistant to supply his place during -his absence. But the appointment lay in the hands of the Board of -Longitude, of which certain clergymen were members; and whether these -worthy ecclesiastics feared that Priestley’s presence among the ship’s -company might expose his Majesty’s Sloop _Resolution_ to the fate which -aforetime befell a certain ship that went from Joppa to Tarshish; or -whether they were alarmed lest a Socinian should undermine that piety -which, in the days of Commodore Trunnion, so strikingly characterised -sailors, does not appear; but, at any rate, they objected to Priestley -“on account of his religious principles,” and appointed the two -Forsters, whose “religious principles,” if they had been known to these -well-meaning but not far-sighted persons, would probably have surprised -them. - -In 1772 another proposal was made to Priestley. Lord Shelburne, -desiring a “literary companion,” had been brought into communication -with Priestley by the good offices of a friend of both, Dr. Price; -and offered him the nominal post of librarian, with a good house -and appointments, and an annuity in case of the termination of the -engagement. Priestley accepted the offer, and remained with Lord -Shelburne for seven years, sometimes residing at Calne, sometimes -travelling abroad with the Earl. - -Why the connection terminated has never been exactly known; but it -is certain that Lord Shelburne behaved with the utmost consideration -and kindness towards Priestley; that he fulfilled his engagements to -the letter; and that, at a later period, he expressed a desire that -Priestley should return to his old footing in his house. Probably -enough, the politician, aspiring to the highest offices in the state, -may have found the position of the protector of a man who was being -denounced all over the country as an infidel and an atheist somewhat -embarrassing. In fact, a passage in Priestley’s “Autobiography” on the -occasion of the publication of his “Disquisitions relating to Matter -and Spirit,” which took place in 1777, indicates pretty clearly the -state of the case:— - - “(126) It being probable that this publication would be - unpopular, and might be the means of bringing odium on - my patron, several attempts were made by his friends, - though none by himself, to dissuade me from persisting - in it. But being, as I thought, engaged in the cause - of important truth, I proceeded without regard to any - consequences, assuring them that this publication should - not be injurious to his lordship.” - -It is not unreasonable to suppose that his lordship, as a keen, -practical man of the world, did not derive much satisfaction from this -assurance. The “evident marks of dissatisfaction” which Priestley says -he first perceived in his patron in 1778, may well have arisen from -the peer’s not unnatural uneasiness as to what his domesticated, but -not tamed, philosopher might write next, and what storm might thereby -be brought down on his own head; and it speaks very highly for Lord -Shelburne’s delicacy that, in the midst of such perplexities, he -made not the least attempt to interfere with Priestley’s freedom of -action. In 1780, however, he intimated to Dr. Price that he should be -glad to establish Priestley on his Irish estates: the suggestion was -interpreted, as Lord Shelburne probably intended it should be, and -Priestley left him, the annuity of £150 a year, which had been promised -in view of such a contingency, being punctually paid. - -After leaving Calne, Priestley spent some little time in London, and -then, having settled in Birmingham at the desire of his brother-in-law, -he was soon invited to become the minister of a large congregation. -This settlement Priestley considered, at the time, to be “the happiest -event of his life.” And well he might think so; for it gave him -competence and leisure; placed him within reach of the best makers -of apparatus of the day; made him a member of that remarkable “Lunar -Society,” at whose meetings he could exchange thoughts with such men -as Watt, Wedgewood, Darwin, and Boulton; and threw open to him the -pleasant house of the Galtons of Barr, where these men, and others of -less note, formed a society of exceptional charm and intelligence.[13] - -But these halcyon days were ended by a bitter storm. The French -Revolution broke out. An electric shock ran through the nations; -whatever there was of corrupt and retrograde, and, at the same time, -a great deal of what there was of best and noblest, in European -society shuddered at the outburst of long-pent-up social fires. -Men’s feelings were excited in a way that we, in this generation, -can hardly comprehend. Party wrath and virulence were expressed in -a manner unparalleled, and it is to be hoped impossible, in our -times; and Priestley and his friends were held up to public scorn, -even in Parliament, as fomenters of sedition. A “Church-and-King” cry -was raised against the Liberal Dissenters; and, in Birmingham, it -was intensified and specially directed towards Priestley by a local -controversy, in which he had engaged with his usual vigour. In 1791, -the celebration of the second anniversary of the taking of the Bastille -by a public dinner, with which Priestley had nothing whatever to do, -gave the signal to the loyal and pious mob, who, unchecked, and indeed -to some extent encouraged, by those who were responsible for order, had -the town at their mercy for three days. The chapels and houses of the -leading Dissenters were wrecked, and Priestley and his family had to -fly for their lives, leaving library, apparatus, papers, and all their -possessions, a prey to the flames. - -Priestley never returned to Birmingham. He bore the outrages and losses -inflicted upon him with extreme patience and sweetness,[14] and betook -himself to London. But even his scientific colleagues gave him a cold -shoulder; and though he was elected minister of a congregation at -Hackney, he felt his position to be insecure, and finally determined on -emigrating to the United States. He landed in America in 1794; lived -quietly with his sons at Northumberland, in Pennsylvania, where his -posterity still flourish; and, clear-headed and busy to the last, died -on the 6th of February 1804. - - -Such were the conditions under which Joseph Priestley did the work -which lay before him, and then, as the Norse Sagas say, went out of the -story. The work itself was of the most varied kind. No human interest -was without its attraction for Priestley, and few men have ever had -so many irons in the fire at once; but, though he may have burned his -fingers a little, very few who have tried that operation have burned -their fingers so little. He made admirable discoveries in science; his -philosophical treatises are still well worth reading; his political -works are full of insight and replete with the spirit of freedom; and -while all these sparks flew off from his anvil, the controversial -hammer rained a hail of blows on orthodox priest and bishop. While -thus engaged, the kindly, cheerful doctor felt no more wrath or -uncharitableness towards his opponents than a smith does towards his -iron. But if the iron could only speak!—and the priests and bishops -took the point of view of the iron. - -No doubt what Priestley’s friends repeatedly urged upon him—that he -would have escaped the heavier trials of his life and done more for the -advancement of knowledge, if he had confined himself to his scientific -pursuits and let his fellow-men go their way—was true. But it seems to -have been Priestley’s feeling that he was a man and a citizen before -he was a philosopher, and that the duties of the two former positions -are at least as imperative as those of the latter. Moreover, there are -men (and I think Priestley was one of them) to whom the satisfaction -of throwing down a triumphant fallacy is as great as that which -attends the discovery of a new truth; who feel better satisfied with -the government of the world, when they have been helping Providence -by knocking an imposture on the head; and who care even more for -freedom of thought than for mere advance of knowledge. These men are -the Carnots who organise victory for truth, and they are, at least, as -important as the generals who visibly fight her battles in the field. - - -Priestley’s reputation as a man of science rests upon his numerous and -important contributions to the chemistry of gaseous bodies; and to form -a just estimate of the value of his work—of the extent to which it -advanced the knowledge of fact and the development of sound theoretical -views—we must reflect what chemistry was in the first half of the -eighteenth century. - -The vast science which now passes under that name had no existence. -Air, water, and fire were still counted among the elemental bodies; -and though Van Helmont, a century before, had distinguished different -kinds of air as _gas ventosum_ and _gas sylvestre_, and Boyle and -Hales had experimentally defined the physical properties of air, and -discriminated some of the various kinds of aëriform bodies, no one -suspected the existence of the numerous totally distinct gaseous -elements which are now known, or dreamed that the air we breathe and -the water we drink are compounds of gaseous elements. - -But, in 1754, a young Scotch physician, Dr. Black, made the first -clearing in this tangled backwood of knowledge. And it gives one a -wonderful impression of the juvenility of scientific chemistry to think -that Lord Brougham, whom so many of us recollect, attended Black’s -lectures when he was a student in Edinburgh. Black’s researches gave -the world the novel and startling conception of a gas that was a -permanently elastic fluid like air, but that differed from common air -in being much heavier, very poisonous, and in having the properties of -an acid, capable of neutralising the strongest alkalies; and it took -the world some time to become accustomed to the notion. - -A dozen years later, one of the most sagacious and accurate -investigators who has adorned this, or any other, country, Henry -Cavendish, published a memoir in the “Philosophical Transactions,” in -which he deals not only with the “fixed air” (now called carbonic acid -or carbonic anhydride) of Black, but with “inflammable air,” or what we -now term hydrogen. - -By the rigorous application of weight and measure to all his processes, -Cavendish implied the belief subsequently formulated by Lavoisier, -that, in chemical processes, matter is neither created nor destroyed, -and indicated the path along which all future explorers must travel. -Nor did he himself halt until this path led him, in 1784, to the -brilliant and fundamental discovery that water is composed of two gases -united in fixed and constant proportions. - -It is a trying ordeal for any man to be compared with Black and -Cavendish, and Priestley cannot be said to stand on their level. -Nevertheless, his achievements are not only great in themselves, but -truly wonderful, if we consider the disadvantages under which he -laboured. Without the careful scientific training of Black, without the -leisure and appliances secured by the wealth of Cavendish, he scaled -the walls of science as so many Englishmen have done before and since -his day; and trusting to mother wit to supply the place of training, -and to ingenuity to create apparatus out of washing tubs, he discovered -more new gases than all his predecessors put together had done. He -laid the foundations of gas analysis; he discovered the complementary -actions of animal and vegetable life upon the constituents of the -atmosphere; and, finally, he crowned his work, this day one hundred -years ago, by the discovery of that “pure dephlogisticated air” to -which the French chemists subsequently gave the name of oxygen. Its -importance, as the constituent of the atmosphere which disappears in -the processes of respiration and combustion, and is restored by green -plants growing in sunshine, was proved somewhat later. For these -brilliant discoveries, the Royal Society elected Priestley a fellow and -gave him their medal, while the Academies of Paris and St. Petersburg -conferred their membership upon him. Edinburgh had made him an -honorary doctor of laws at an early period of his career; but, I need -hardly add, that a man of Priestley’s opinions received no recognition -from the universities of his own country. - -That Priestley’s contributions to the knowledge of chemical fact were -of the greatest importance, and that they richly deserve all the praise -that has been awarded to them, is unquestionable; but it must, at the -same time, be admitted that he had no comprehension of the deeper -significance of his work; and, so far from contributing anything to the -theory of the facts which he discovered, or assisting in their rational -explanation, his influence to the end of his life was warmly exerted -in favour of error. From first to last, he was a stiff adherent of the -phlogiston doctrine which was prevalent when his studies commenced; -and, by a curious irony of fate, the man who by the discovery of what -he called “dephlogisticated air” furnished the essential datum for the -true theory of combustion, of respiration, and of the composition of -water, to the end of his days fought against the inevitable corollaries -from his own labours. His last scientific work, published in 1800, -bears the title, “The Doctrine of Phlogiston established, and that of -the Composition of Water refuted.” - -When Priestley commenced his studies, the current belief was, that -atmospheric air, freed from accidental impurities, is a simple -elementary substance, indestructible and unalterable, as water was -supposed to be. When a combustible burned, or when an animal breathed -in air, it was supposed that a substance, “phlogiston,” the matter of -heat and light, passed from the burning or breathing body into it, -and destroyed its powers of supporting life and combustion. Thus, air -contained in a vessel in which a lighted candle had gone out, or a -living animal had breathed until it could breathe no longer, was called -“phlogisticated.” The same result was supposed to be brought about by -the addition of what Priestley called “nitrous gas” to common air. - -In the course of his researches, Priestley found that the quantity of -common air which can thus become “phlogisticated,” amounts to about -one-fifth the volume of the whole quantity submitted to experiment. -Hence it appeared that common air consists, to the extent of -four-fifths of its volume, of air which is already “phlogisticated;” -while the other fifth is free from phlogiston, or “dephlogisticated.” -On the other hand, Priestley found that air “phlogisticated” by -combustion or respiration could be “dephlogisticated,” or have the -properties of pure common air restored to it, by the action of green -plants in sunshine. The question, therefore, would naturally arise—as -common air can be wholly phlogisticated by combustion, and converted -into a substance which will no longer support combustion, is it -possible to get air that shall be less phlogisticated than common air, -and consequently support combustion better than common air does? - -Now, Priestley says that, in 1774, the possibility of obtaining air -less phlogisticated than common air had not occurred to him.[15] But -in pursuing his experiments on the evolution of air from various bodies -by means of heat, it happened that, on the 1st of August 1774, he threw -the heat of the sun, by means of a large burning glass which he had -recently obtained, upon a substance which was then called _mercurius -calcinatus per se_, and which is commonly known as red precipitate. - - “I presently found that, by means of this lens, air was - expelled from it very readily. Having got about three - or four times as much as the bulk of my materials, I - admitted water to it, and found that it was not imbibed - by it. But what surprised me more than I can well - express, was that a candle burned in this air with a - remarkably vigorous flame, very much like that enlarged - flame with which a candle burns in nitrous air, exposed - to iron or lime of sulphur; but as I had got nothing like - this remarkable appearance from any kind of air besides - this particular modification of nitrous air, and I knew - no nitrous acid was used in the preparation of _mercurius - calcinatus_, I was utterly at a loss how to account for - it. - - “In this case also, though I did not give sufficient - attention to the circumstance at that time, the flame - of the candle, besides being larger, burned with more - splendour and heat than in that species of nitrous air; - and a piece of red-hot wood sparkled in it, exactly like - paper dipped in a solution of nitre, and it consumed very - fast—an experiment which I had never thought of trying - with nitrous air.”[16] - -Priestley obtained the same sort of air from red lead, but, as he says -himself, he remained in ignorance of the properties of this new kind of -air for seven months, or until March 1775, when he found that the new -air behaved with “nitrous gas” in the same way as the dephlogisticated -part of common air does;[17] but that, instead of being diminished to -four-fifths, it almost completely vanished, and, therefore, showed -itself to be “between five and six times as good as the best common -air I have ever met with.”[18] As this new air thus appeared to be -completely free from phlogiston, Priestley called it “dephlogisticated -air.” - -What was the nature of this air? Priestley found that the same kind of -air was to be obtained by moistening with the spirit of nitre (which he -terms nitrous acid) any kind of earth that is free from phlogiston, and -applying heat; and consequently he says: “There remained no doubt on -my mind but that the atmospherical air, or the thing that we breathe, -consists of the nitrous acid and earth, with so much phlogiston as is -necessary to its elasticity, and likewise so much more as is required -to bring it from its state of perfect purity to the mean condition in -which we find it.”[19] - - -Priestley’s view, in fact, is that atmospheric air is a kind of -saltpetre, in which the potash is replaced by some unknown earth. -And in speculating on the manner in which saltpetre is formed, -he enunciates the hypothesis, “that nitre is formed by a real -_decomposition of the air itself_, the _bases_ that are presented to -it having, in such circumstances, a nearer affinity with the spirit -of nitre than that kind of earth with which it is united in the -atmosphere.”[20] - -It would have been hard for the most ingenious person to have wandered -farther from the truth than Priestley does in this hypothesis; and, -though Lavoisier undoubtedly treated Priestley very ill, and pretended -to have discovered dephlogisticated air, or oxygen, as he called it, -independently, we can almost forgive him, when we reflect how different -were the ideas which the great French chemist attached to the body -which Priestley discovered. - -They are like two navigators of whom the first sees a new country, but -takes clouds for mountains and mirage for lowlands; while the second -determines its length and breadth, and lays down on a chart its exact -place, so that, thenceforth, it serves as a guide to his successors, -and becomes a secure outpost whence new explorations may be pushed. - -Nevertheless, as Priestley himself somewhere remarks, the first object -of physical science is to ascertain facts, and the service which he -rendered to chemistry by the definite establishment of a large number -of new and fundamentally important facts, is such as to entitle him to -a very high place among the fathers of chemical science. - - -It is difficult to say whether Priestley’s philosophical, political, or -theological views were most responsible for the bitter hatred which was -borne to him by a large body of his countrymen,[21] and which found -its expression in the malignant insinuations in which Burke, to his -everlasting shame, indulged in the House of Commons. - -Without containing much that will be new to the readers of Hobbes, -Spinoza, Collins, Hume, and Hartley, and, indeed, while making no -pretensions to originality, Priestley’s “Disquisitions relating to -Matter and Spirit,” and his “Doctrine of Philosophical Necessity -illustrated,” are among the most powerful, clear, and unflinching -expositions of materialism and necessarianism which exist in the -English language, and are still well worth reading. - -Priestley denied the freedom of the will in the sense of its -self-determination; he denied the existence of a soul distinct from the -body; and as a natural consequence, he denied the natural immortality -of man. - -In relation to these matters English opinion, a century ago, was very -much what it is now. - -A man may be a necessarian without incurring graver reproach than that -implied in being called a gloomy fanatic, necessarianism, though very -shocking, having a note of Calvinistic orthodoxy; but, if a man is a -materialist; or, if good authorities say he is and must be so, in spite -of his assertion to the contrary; or, if he acknowledge himself unable -to see good reasons for believing in the natural immortality of man, -respectable folks look upon him as an unsafe neighbour of a cash-box, -as an actual or potential sensualist, the more virtuous in outward -seeming, the more certainly loaded with secret “grave personal sins.” - -Nevertheless, it is as certain as anything can be, that Joseph -Priestley was no gloomy fanatic, but as cheerful and kindly a soul as -ever breathed, the idol of children; a man who was hated only by those -who did not know him, and who charmed away the bitterest prejudices -in personal intercourse; a man who never lost a friend, and the best -testimony to whose worth is the generous and tender warmth with which -his many friends vied with one another in rendering him substantial -help, in all the crises of his career. - -The unspotted purity of Priestley’s life, the strictness of -his performance of every duty, his transparent sincerity, the -unostentatious and deep-seated piety which breathes through all his -correspondence, are in themselves a sufficient refutation of the -hypothesis, invented by bigots to cover uncharitableness, that such -opinions as his must arise from moral defects. And his statue will do -as good service as the brazen image that was set upon a pole before -the Israelites, if those who have been bitten by the fiery serpents of -sectarian hatred, which still haunt this wilderness of a world, are -made whole by looking upon the image of a heretic, who was yet a saint. - -Though Priestley did not believe in the natural immortality of man, he -held with an almost naïve realism, that man would be raised from the -dead by a direct exertion of the power of God, and thenceforward be -immortal. And it may be as well for those who may be shocked by this -doctrine to know that views, substantially identical with Priestley’s, -have been advocated, since his time, by two prelates of the Anglican -Church: by Dr. Whately, Archbishop of Dublin, in his well-known -“Essays;”[22] and by Dr. Courtenay, Bishop of Kingston in Jamaica, -the first edition of whose remarkable book “On the Future States,” -dedicated to Archbishop Whately, was published in 1843 and the second -in 1857. According to Bishop Courtenay, - - “The death of the body will cause a cessation of all the - activity of the mind by way of natural consequence; to - continue for ever UNLESS the Creator should interfere.” - -And again:— - - “The natural end of human existence is the ‘first death,’ - the dreamless slumber of the grave, wherein man lies - spellbound, soul and body, under the dominion of sin - and death—that whatever modes of conscious existence, - whatever future states of ‘life’ or of ‘torment’ beyond - Hades are reserved for man, are results of our blessed - Lord’s victory over sin and death; that the resurrection - of the dead must be preliminary to their entrance into - either of the future states, and that the nature and even - existence of these states and even the mere fact that - there is a futurity of consciousness, can be known _only_ - through God’s revelation of Himself in the Person and the - Gospel of His Son.”—P. 389. - -And now hear Priestley:— - - “Man, according to this system (of materialism), is no - more than we now see of him. His being commences at - the time of his conception, or perhaps at an earlier - period. The corporeal and mental faculties, in being in - the same substance, grow, ripen, and decay together; - and whenever the system is dissolved it continues in a - state of dissolution till it shall please that Almighty - Being who called it into existence to restore it to life - again.”—“Matter and Spirit,” p. 49. - -And again:— - - “The doctrine of the Scripture is, that God made man of - the dust of the ground, and by simply animating this - organised matter, made man that living percipient and - intelligent being that he is. According to Revelation, - _death_ is a state of rest and insensibility, and our - only though sure hope of a future life is founded on - the doctrine of the resurrection of the whole man at - some distant period; this assurance being sufficiently - confirmed to us both by the evident tokens of a Divine - commission attending the persons who delivered the - doctrine, and especially by the actual resurrection of - Jesus Christ, which is more authentically attested than - any other fact in history.”—_Ibid._, p. 247. - -We all know that “a saint in crape is twice a saint in lawn;” but -it is not yet admitted that the views which are consistent with -such saintliness in lawn, become diabolical when held by a mere -dissenter.[23] - -I am not here either to defend or to attack Priestley’s philosophical -views, and I cannot say that I am personally disposed to attach much -value to episcopal authority in philosophical questions; but it seems -right to call attention to the fact, that those of Priestley’s opinions -which have brought most odium upon him, have been openly promulgated, -without challenge, by persons occupying the highest positions in the -State Church. - -I must confess that what interests me most about Priestley’s -materialism, is the evidence that he saw dimly the seed of destruction -which such materialism carries within its own bosom. In the course -of his reading for his “History of Discoveries relating to Vision, -Light, and Colours,” he had come upon the speculations of Boscovich -and Michell, and had been led to admit the sufficiently obvious truth -that our knowledge of matter is a knowledge of its properties; and that -of its substance—if it have a substance—we know nothing. And this led -to the further admission that, so far as we can know, there may be no -difference between the substance of matter and the substance of spirit -(“Disquisitions,” p. 16). A step farther would have shown Priestley -that his materialism was, essentially, very little different from the -Idealism of his contemporary, the Bishop of Cloyne. - - -As Priestley’s philosophy is mainly a clear statement of the views of -the deeper thinkers of his day, so are his political conceptions based -upon those of Locke. Locke’s aphorism that “the end of government is -the good of mankind,” is thus expanded by Priestley:— - - “It must necessarily be understood, therefore, whether it - be expressed or not, that all people live in society for - their mutual advantage; so that the good and happiness - of the members, that is, of the majority of the members, - of any state, is the great standard by which everything - relating to that state must finally be determined.”[24] - -The little sentence here interpolated, “that is, of the majority of -the members of any state,” appears to be that passage which suggested -to Bentham, according to his own acknowledgment, the famous “greatest -happiness” formula, which by substituting “happiness” for “good,” has -converted a noble into an ignoble principle. But I do not call to -mind that there is any utterance in Locke quite so outspoken as the -following passage in the “Essay on the First Principles of Government.” -After laying down as “a fundamental maxim in all governments,” the -proposition that “kings, senators, and nobles” are “the servants of the -public,” Priestley goes on to say:— - - “But in the largest states, if the abuses of the - government should at any time be great and manifest; if - the servants of the people, forgetting their masters and - their masters’ interest, should pursue a separate one - of their own; if, instead of considering that they are - made for the people, they should consider the people as - made for them; if the oppressions and violation of right - should be great, flagrant, and universally resented; if - the tyrannical governors should have no friends but a few - sycophants, who had long preyed upon the vitals of their - fellow-citizens, and who might be expected to desert a - government whenever their interests should be detached - from it; if, in consequence of these circumstances, it - should become manifest that the risk which would be - run in attempting a revolution would be trifling, and - the evils which might be apprehended from it were far - less than those which were actually suffered and which - were daily increasing; in the name of God, I ask, what - principles are those which ought to restrain an injured - and insulted people from asserting their natural rights, - and from changing or even punishing their governors—that - is, their servants—who had abused their trust, or from - altering the whole form of their government, if it - appeared to be of a structure so liable to abuse?” - -As a Dissenter, subject to the operation of the Corporation and Test -Acts, and as a Unitarian, excluded from the benefit of the Toleration -Act, it is not surprising to find that Priestley had very definite -opinions about Ecclesiastical Establishments; the only wonder is that -these opinions were so moderate as the following passages show them to -have been:— - - “Ecclesiastical authority may have been necessary in the - infant state of society, and, for the same reason, it - may perhaps continue to be, in some degree, necessary as - long as society is imperfect; and therefore may not be - entirely abolished till civil governments have arrived - at a much greater degree of perfection. If, therefore, - I were asked whether I should approve of the immediate - dissolution of all the ecclesiastical establishments in - Europe, I should answer, No.... Let experiment be first - made of _alterations_, or, which is the same thing, of - _better establishments_ than the present. Let them be - reformed in many essential articles, and then not thrown - aside entirely till it be found by experience that no - good can be made of them.” - -Priestley goes on to suggest four such reforms of a capital nature:— - - “1. Let the Articles of Faith to be subscribed by - candidates for the ministry be greatly reduced. In - the formulary of the Church of England, might not - thirty-eight out of the thirty-nine be very well spared? - It is a reproach to any Christian establishment if every - man cannot claim the benefit of it who can say that he - believes in the religion of Jesus Christ as it is set - forth in the New Testament. You say the terms are so - general that even Deists would quibble and insinuate - themselves. I answer that all the articles which are - subscribed at present, by no means exclude Deists who - will prevaricate; and upon this scheme you would at least - exclude fewer honest men.”[25] - -The second reform suggested is the equalisation, in proportion to work -done, of the stipends of the clergy; the third, the exclusion of the -bishops from Parliament; and the fourth, complete toleration, so that -every man may enjoy the rights of a citizen, and be qualified to serve -his country, whether he belong to the Established Church or not. - -Opinions such as those I have quoted, respecting the duties and -the responsibilities of governors, are the commonplaces of modern -Liberalism; and Priestley’s views on Ecclesiastical Establishments -would, I fear, meet with but a cool reception, as altogether too -conservative, from a large proportion of the lineal descendants of the -people who taught their children to cry “Damn Priestley;” and, with -that love for the practical application of science which is the source -of the greatness of Birmingham, tried to set fire to the doctor’s house -with sparks from his own electrical machine; thereby giving the man -they called an incendiary and raiser of sedition against Church and -King, an appropriately experimental illustration of the nature of arson -and riot. - - -If I have succeeded in putting before you the main features of -Priestley’s work, its value will become apparent, when we compare the -condition of the English nation, as he knew it, with its present state. - -The fact that France has been for eighty-five years trying, without -much success, to right herself after the great storm of the Revolution, -is not unfrequently cited among us, as an indication of some inherent -incapacity for self-government among the French people. I think, -however, that Englishmen who argue thus, forget that, from the meeting -of the Long Parliament in 1640, to the last Stuart rebellion in 1745, -is a hundred and five years, and that, in the middle of the last -century, we had but just safely freed ourselves from our Bourbons and -all that they represented. The corruption of our state was as bad as -that of the Second Empire. Bribery was the instrument of government, -and peculation its reward. Four-fifths of the seats in the House of -Commons were more or less openly dealt with as property. A minister -had to consider the state of the vote market, and the sovereign secured -a sufficiency of “king’s friends” by payments allotted with retail, -rather than royal, sagacity. - -Barefaced and brutal immorality and intemperance pervaded the land, -from the highest to the lowest classes of society. The Established -Church was torpid, so far as it was not a scandal; but those who -dissented from it came within the meshes of the Act of Uniformity, the -Test Act, and the Corporation Act. By law, such a man as Priestley, -being a Unitarian, could neither teach nor preach, and was liable to -ruinous fines and long imprisonment.[26] In those days, the guns that -were pointed by the Church against the Dissenters were shotted. The law -was a cesspool of iniquity and cruelty. Adam Smith was a new prophet -whom few regarded, and commerce was hampered by idiotic impediments, -and ruined by still more absurd help, on the part of government. - -Birmingham, though already the centre of a considerable industry, was a -mere village as compared with its present extent. People who travelled -went about armed, by reason of the abundance of highwaymen and the -paucity and inefficiency of the police. Stage coaches had not reached -Birmingham, and it took three days to get to London. Even canals were a -recent and much opposed invention. - -Newton had laid the foundation of a mechanical conception of the -physical universe: Hartley, putting a modern face upon ancient -materialism, had extended that mechanical conception to psychology; -Linnæus and Haller were beginning to introduce method and order into -the chaotic accumulation of biological facts. But those parts of -physical science which deal with heat, electricity, and magnetism, -and above all, chemistry, in the modern sense, can hardly be said -to have had an existence. No one knew that two of the old elemental -bodies, air and water, are compounds, and that a third, fire, is not a -substance but a motion. The great industries that have grown out of the -applications of modern scientific discoveries had no existence, and the -man who should have foretold their coming into being in the days of his -son, would have been regarded as a mad enthusiast. - -In common with many other excellent persons, Priestley believed that -man is capable of reaching, and will eventually attain, perfection. -If the temperature of space presented no obstacle, I should be glad -to entertain the same idea; but judging from the past progress of our -species, I am afraid that the globe will have cooled down so far, -before the advent of this natural millennium, that we shall be, at -best, perfected Esquimaux. For all practical purposes, however, it -is enough that man may visibly improve his condition in the course -of a century or so. And, if the picture of the state of things -in Priestley’s time, which I have just drawn, have any pretence -to accuracy, I think it must be admitted that there has been a -considerable change for the better. - -I need not advert to the well-worn topic of material advancement, in -a place in which the very stones testify to that progress—in the town -of Watt and of Boulton. I will only remark, in passing, that material -advancement has its share in moral and intellectual progress. Becky -Sharp’s acute remark that it is not difficult to be virtuous on ten -thousand a year, has its application to nations; and it is futile to -expect a hungry and squalid population to be anything but violent and -gross. But as regards other than material welfare, although perfection -is not yet in sight—even from the mast-head—it is surely true that -things are much better than they were. - -Take the upper and middle classes as a whole, and it may be said -that open immorality and gross intemperance have vanished. Four and -six bottle men are as extinct as the dodo. Women of good repute -do not gamble, and talk modelled upon Dean Swift’s “Art of Polite -Conversation” would be tolerated in no decent kitchen. - -Members of the legislature are not to be bought; and constituents are -awakening to the fact that votes must not be sold—even for such trifles -as rabbits and tea and cake. Political power has passed into the hands -of the masses of the people. Those whom Priestley calls their servants -have recognised their position, and have requested the master to be -so good as to go to school and fit himself for the administration of -his property. No civil disability attaches to any one on theological -grounds, and the highest offices of the state are open to Papist, Jew, -or Secularist.[27] - -Whatever men’s opinions as to the policy of Establishment, no one -can hesitate to admit that the clergy of the Church are men of pure -life and conversation, zealous in the discharge of their duties; and, -at present, apparently, more bent on prosecuting one another than -on meddling with Dissenters. Theology itself has broadened so much, -that Anglican divines put forward doctrines more liberal than those -of Priestley; and, in our state-supported churches, one listener may -hear a sermon to which Bossuet might have given his approbation, while -another may hear a discourse in which Socrates would find nothing new. - -But great as these changes may be, they sink into insignificance -beside the progress of physical science, whether we consider the -improvement of methods of investigation, or the increase in bulk of -solid knowledge. Consider that the labours of Laplace, of Young, of -Davy, and of Faraday; of Cuvier, of Lamarck, and of Robert Brown; of -Von Baer, and of Schwann; of Smith and of Hutton, have all been carried -on since Priestley discovered oxygen; and consider that they are now -things of the past, concealed by the industry of those who have built -upon them, as the first founders of a coral reef are hidden beneath the -life’s work of their successors; consider that the methods of physical -science are slowly spreading into all investigations, and that proofs -as valid as those required by her canons of investigation, are being -demanded of all doctrines which ask for men’s assent; and you will -have a faint image of the astounding difference in this respect between -the nineteenth century and the eighteenth. - -If we ask what is the deeper meaning of all these vast changes, I -think there can be but one reply. They mean that reason has asserted -and exercised her primacy over all provinces of human activity: that -ecclesiastical authority has been relegated to its proper place; that -the good of the governed has been finally recognised as the end of -government, and the complete responsibility of governors to the people -as its means; and that the dependence of natural phenomena in general, -on the laws of action of what we call matter has become an axiom. - -But it was to bring these things about, and to enforce the recognition -of these truths, that Joseph Priestley laboured. If the nineteenth -century is other and better than the eighteenth, it is, in great -measure, to him and to such men as he, that we owe the change. If the -twentieth century is to be better than the nineteenth, it will be -because there are among us men who walk in Priestley’s footsteps. - -Such men are not those whom their own generation delights to honour; -such men, in fact, rarely trouble themselves about honour, but ask, -in another spirit than Falstaff’s, “What is honour? Who hath it? He -that died o’ Wednesday.” But whether Priestley’s lot be theirs, and a -future generation, in justice and in gratitude, set up their statues; -or whether their names and fame are blotted out from remembrance, -their work will live as long as time endures. To all eternity, the -sum of truth and right will have been increased by their means; to all -eternity, falsehood and injustice will be the weaker because they have -lived. - - - - -VI. - -ON THE METHOD OF ZADIG: - -RETROSPECTIVE PROPHECY AS A FUNCTION OF SCIENCE. - - “Une marque plus sûre que toutes celles de Zadig”—CUVIER.[28] - - -It is a usual and a commendable practice to preface the discussion of -the views of a philosophic thinker by some account of the man and of -the circumstances which shaped his life and coloured his way of looking -at things; but, though Zadig is cited in one of the most important -chapters of Cuvier’s greatest work, little is known about him, and that -little might perhaps be better authenticated than it is. - -It is said that he lived at Babylon in the time of King Moabdar; -but the name of Moabdar does not appear in the list of Babylonian -sovereigns brought to light by the patience and the industry of the -decipherers of cuneiform inscriptions in these later years; nor indeed -am I aware that there is any other authority for his existence than -that of the biographer of Zadig, one Arouet de Voltaire, among whose -more conspicuous merits strict historical accuracy is perhaps hardly -to be reckoned. - -Happily Zadig is in the position of a great many other philosophers. -What he was like when he was in the flesh, indeed whether he existed at -all, are matters of no great consequence. What we care about in a light -is that it shows the way, not whether it is lamp or candle, tallow or -wax. Our only real interest in Zadig lies in the conceptions of which -he is the putative father; and his biographer has stated these with so -much clearness and vivacious illustration, that we need hardly feel a -pang, even if critical research should prove King Moabdar and all the -rest of the story to be unhistorical, and reduce Zadig himself to the -shadowy condition of a solar myth. - -Voltaire tells us that, disenchanted with life by sundry domestic -misadventures, Zadig withdrew from the turmoil of Babylon to a secluded -retreat on the banks of the Euphrates, where he beguiled his solitude -by the study of nature. The manifold wonders of the world of life -had a particular attraction for the lonely student; incessant and -patient observation of the plants and animals about him sharpened -his naturally good powers of observation and of reasoning; until, at -length, he acquired a sagacity which enabled him to perceive endless -minute differences among objects which, to the untutored eye, appeared -absolutely alike. - -It might have been expected that this enlargement of the powers of the -mind and of its store of natural knowledge could tend to nothing but -the increase of a man’s own welfare and the good of his fellow-men. -But Zadig was fated to experience the vanity of such expectations. - - One day, walking near a little wood, he saw, hastening - that way, one of the Queen’s chief eunuchs, followed by - a troop of officials, who appeared to be in the greatest - anxiety, running hither and thither like men distraught, - in search of some lost treasure. - - “Young man,” cried the eunuch, “have you seen the Queen’s - dog?” Zadig answered modestly, “A bitch, I think, not - a dog.” “Quite right,” replied the eunuch; and Zadig - continued, “A very small spaniel who has lately had - puppies; she limps with the left foreleg, and has very - long ears.” “Ah! you have seen her then,” said the - breathless eunuch. “No,” answered Zadig, “I have not seen - her; and I really was not aware that the Queen possessed - a spaniel.” - - By an odd coincidence, at the very same time, the - handsomest horse in the King’s stables broke away from - his groom in the Babylonian plains. The grand huntsman - and all his staff were seeking the horse with as much - anxiety as the eunuch and his people the spaniel; and the - grand huntsman asked Zadig if he had not seen the King’s - horse go that way. - - “A first-rate galloper, small-hoofed, five feet high; - tail three feet and a half long; cheek pieces of the bit - of twenty-three carat gold; shoes silver?” said Zadig. - - “Which way did he go? Where is he?” cried the grand - huntsman. - - “I have not seen anything of the horse, and I never heard - of him before,” replied Zadig. - - The grand huntsman and the chief eunuch made sure that - Zadig had stolen both the King’s horse and the Queen’s - spaniel, so they haled him before the High Court of - Desterham, which at once condemned him to the knout, and - transportation for life to Siberia. But the sentence was - hardly pronounced when the lost horse and spaniel were - found. So the judges were under the painful necessity of - reconsidering their decision: but they fined Zadig four - hundred ounces of gold for saying he had seen that which - he had not seen. - - The first thing was to pay the fine; afterwards Zadig was - permitted to open his defence to the court, which he did - in the following terms: - - “Stars of justice, abysses of knowledge, mirrors - of truth, whose gravity is as that of lead, whose - inflexibility is as that of iron, who rival the diamond - in clearness, and possess no little affinity with gold; - since I am permitted to address your august assembly, I - swear by Ormuzd that I have never seen the respectable - lady dog of the queen, nor beheld the sacrosanct horse of - the King of Kings. - - “This is what happened. I was taking a walk towards the - little wood near which I subsequently had the honour to - meet the venerable chief eunuch and the most illustrious - grand huntsman. I noticed the track of an animal in the - sand, and it was easy to see that it was that of a small - dog. Long faint streaks upon the little elevations of - sand between the footmarks convinced me that it was a - she dog with pendent dugs, showing that she must have - had puppies not many days since. Other scrapings of - the sand, which always lay close to the marks of the - forepaws, indicated that she had very long ears; and, as - the imprint of one foot was always fainter than those of - the other three, I judged that the lady dog of our august - Queen was, if I may venture to say so, a little lame. - - “With respect to the horse of the King of Kings, permit - me to observe that, wandering through the paths which - traverse the wood, I noticed the marks of horse-shoes. - They were all equidistant. ‘Ah!’ said I, ‘this is a - famous galloper.’ In a narrow alley, only seven feet - wide, the dust upon the trunks of the trees was a little - disturbed at three feet and a half from the middle of - the path. ‘This horse,’ said I to myself, ‘had a tail - three feet and a half long, and, lashing it from one side - to the other, he has swept away the dust.’ Branches of - the trees met overhead at the height of five feet, and - under them I saw newly fallen leaves; so I knew that the - horse had brushed some of the branches, and was therefore - five feet high. As to his bit, it must have been made of - twenty-three carat gold, for he had rubbed it against - a stone, which turned out to be a touchstone, with the - properties of which I am familiar by experiment. Lastly, - by the marks which his shoes left upon pebbles of another - kind, I was led to think that his shoes were of fine - silver.” - - All the judges admired Zadig’s profound and subtle - discernment; and the fame of it reached even the King and - the Queen. From the ante-rooms to the presence-chamber, - Zadig’s name was in everybody’s mouth; and, although many - of the magi were of opinion that he ought to be burnt - as a sorcerer, the King commanded that the four hundred - ounces of gold which he had been fined should be restored - to him. So the officers of the court went in state with - the four hundred ounces; only they retained three hundred - and ninety-eight for legal expenses, and their servants - expected fees. - -Those who are interested in learning more of the fateful history of -Zadig must turn to the original; we are dealing with him only as a -philosopher, and this brief excerpt suffices for the exemplification of -the nature of his conclusions and of the method by which he arrived at -them. - -These conclusions may be said to be of the nature of retrospective -prophecies; though it is perhaps a little hazardous to employ -phraseology which perilously suggests a contradiction in terms—the -word “prophecy” being so constantly in ordinary use restricted to -“foretelling.” Strictly, however, the term prophecy as much applies to -outspeaking as to foretelling; and, even in the restricted sense of -“divination,” it is obvious that the essence of the prophetic operation -does not lie in its backward or forward relation to the course of time, -but in the fact that it is the apprehension of that which lies out of -the sphere of immediate knowledge; the seeing of that which to the -natural sense of the seer is invisible. - -The foreteller asserts that, at some future time, a properly situated -observer will witness certain events; the clairvoyant declares that, -at this present time, certain things are to be witnessed a thousand -miles away; the retrospective prophet (would that there were such a -word as “backteller!”) affirms that so many hours or years ago, such -and such things were to be seen. In all these cases, it is only the -relation to time which alters—the process of divination beyond the -limits of possible direct knowledge remains the same. - -No doubt it was their instinctive recognition of the analogy between -Zadig’s results and those obtained by authorised inspiration which -inspired the Babylonian magi with the desire to burn the philosopher. -Zadig admitted that he had never either seen or heard of the horse of -the king or of the spaniel of the queen; and yet he ventured to assert -in the most positive manner that animals answering to their description -did actually exist, and ran about the plains of Babylon. If his method -was good for the divination of the course of events ten hours old, why -should it not be good for those of ten years or ten centuries past; -nay, might it not extend to ten thousand years and justify the impious -in meddling with the traditions of Oannes and the fish, and all the -sacred foundations of Babylonian cosmogony? - -But this was not the worst. There was another consideration which -obviously dictated to the more thoughtful of the magi the propriety -of burning Zadig out of hand. His defence was worse than his offence. -It showed that his mode of divination was fraught with danger to -magianism in general. Swollen with the pride of human reason, he had -ignored the established canons of magian lore; and, trusting to what -after all was mere carnal common sense, he professed to lead men to -a deeper insight into nature than magian wisdom, with all its lofty -antagonism to everything common, had ever reached. What, in fact, lay -at the foundation of all Zadig’s arguments but the coarse commonplace -assumption, upon which every act of our daily lives is based, that we -may conclude from an effect to the pre-existence of a cause competent -to produce that effect? - -The tracks were exactly like those which dogs and horses leave; -therefore they were the effects of such animals as causes. The marks -at the sides of the fore prints of the dog track were exactly such -as would be produced by long trailing ears; therefore the dog’s long -ears were the causes of these marks—and so on. Nothing can be more -hopelessly vulgar, more unlike the majestic development of a system -of grandly unintelligible conclusions from sublimely inconceivable -premisses, such as delights the magian heart. In fact, Zadig’s method -was nothing but the method of all mankind. Retrospective prophecies, -far more astonishing for their minute accuracy than those of Zadig, are -familiar to those who have watched the daily life of nomadic people. - -From freshly broken twigs, crushed leaves, disturbed pebbles, and -imprints hardly discernible by the untrained eye, such graduates in -the University of Nature will divine, not only the fact that a party -has passed that way, but its strength, its composition, the course -it took, and the number of hours or days which have elapsed since it -passed. But they are able to do this because, like Zadig, they perceive -endless minute differences where untrained eyes discern nothing; and -because the unconscious logic of common sense compels them to account -for these effects by the causes which they know to be competent to -produce them. - -And such mere methodised savagery was to discover the hidden things -of nature better than _à priori_ deductions from the nature of -Ormuzd—perhaps to give a history of the past, in which Oannes would be -altogether ignored! Decidedly it were better to burn this man at once. - -If instinct, or an unwonted use of reason, led Moabdar’s magi to -this conclusion two or three thousand years ago, all that can be -said is that subsequent history has fully justified them. For the -rigorous application of Zadig’s logic to the results of accurate and -long-continued observation has founded all those sciences which -have been termed historical or palætiological, because they are -retrospectively prophetic and strive towards the reconstruction in -human imagination of events which have vanished and ceased to be. - -History, in the ordinary acceptation of the word, is based upon the -interpretation of documentary evidence; and documents would have no -evidential value unless historians were justified in their assumption -that they have come into existence by the operation of causes similar -to those of which documents are, in our present experience, the -effects. If a written history can be produced otherwise than by human -agency, or if the man who wrote a given document was actuated by other -than ordinary human motives, such documents are of no more evidential -value than so many arabesques. - -Archæology, which takes up the thread of history beyond the point at -which documentary evidence fails us, could have no existence, except -for our well-grounded confidence that monuments and works of art or -artifice, have never been produced by causes different in kind from -those to which they now owe their origin. And geology, which traces -back the course of history beyond the limits of archæology, could tell -us nothing except for the assumption that, millions of years ago, -water, heat, gravitation, friction, animal and vegetable life, caused -effects of the same kind as they do now. Nay, even physical astronomy, -in so far as it takes us back to the uttermost point of time which -palætiological science can reach, is founded upon the same assumption. -If the law of gravitation ever failed to be true, even to the smallest -extent, for that period, the calculations of the astronomer have no -application. - -The power of prediction, of prospective prophecy, is that which is -commonly regarded as the great prerogative of physical science. And -truly it is a wonderful fact that one can go into a shop and buy for -small price a book, the “Nautical Almanac,” which will foretell the -exact position to be occupied by one of Jupiter’s moons six months -hence; nay more, that, if it were worth while, the Astronomer Royal -could furnish us with as infallible a prediction applicable to 1980 or -2980. - -But astronomy is not less remarkable for its power of retrospective -prophecy. - -Thales, oldest of Greek philosophers, the dates of whose birth and -death are uncertain, but who flourished about 600 B.C., is said to have -foretold an eclipse of the sun which took place in his time during a -battle between the Medes and the Lydians. Sir George Airy has written a -very learned and interesting memoir[29] in which he proves that such an -eclipse was visible in Lydia on the afternoon of the 28th of May in the -year 585 B.C. - -No one doubts that, on the day and at the hour mentioned by the -Astronomer Royal, the people of Asia Minor saw the face of the sun -totally obscured. But, though we implicitly believe this retrospective -prophecy, it is incapable of verification. In the total absence of -historical records, it is impossible even to conceive any means of -ascertaining directly whether the eclipse of Thales happened or not. -All that can be said is, that the prospective prophecies of the -astronomer are always verified; and that, inasmuch as his retrospective -prophecies are the result of following backwards, the very same method -as that which invariably leads to verified results, when it is worked -forwards, there is as much reason for placing full confidence in the -one as in the other. Retrospective prophecy is therefore a legitimate -function of astronomical science; and if it is legitimate for one -science it is legitimate for all; the fundamental axiom on which -it rests, the constancy of the order of nature, being the common -foundation of all scientific thought. Indeed, if there can be grades -in legitimacy, certain branches of science have the advantage over -astronomy, in so far as their retrospective prophecies are not only -susceptible of verification, but are sometimes strikingly verified. - -Such a science exists in that application of the principles of biology -to the interpretation of the animal and vegetable remains imbedded -in the rocks which compose the surface of the globe, which is called -Palæontology. - -At no very distant time, the question whether these so-called “fossils” -were really the remains of animals and plants was hotly disputed. Very -learned persons maintained that they were nothing of the kind, but a -sort of concretion, or crystallisation, which had taken place within -the stone in which they are found; and which simulated the forms of -animal and vegetable life, just as frost on a window-pane imitates -vegetation. At the present day, it would probably be impossible -to find any sane advocate of this opinion; and the fact is rather -surprising, that among the people from whom the circle-squarers, -perpetual-motioners, flat-earth men and the like, are recruited, to say -nothing of table-turners and spirit-rappers, somebody has not perceived -the easy avenue to nonsensical notoriety open to any one who will take -up the good old doctrine, that fossils are all _lusus naturæ_. - -The position would be impregnable, inasmuch as it is quite impossible -to prove the contrary. If a man choose to maintain that a fossil -oyster shell, in spite of its correspondence, down to every minutest -particular, with that of an oyster fresh taken out of the sea, was -never tenanted by a living oyster, but is a mineral concretion, there -is no demonstrating his error. All that can be done is to show him -that, by a parity of reasoning, he is bound to admit that a heap of -oyster shells outside a fishmonger’s door may also be “sports of -nature,” and that a mutton bone in a dust-bin may have had the like -origin. And when you cannot prove that people are wrong, but only that -they are absurd, the best course is to let them alone. - -The whole fabric of palæontology, in fact, falls to the ground unless -we admit the validity of Zadig’s great principle, that like effects -imply like causes; and that the process of reasoning from a shell, or -a tooth, or a bone, to the nature of the animal to which it belonged, -rests absolutely on the assumption that the likeness of this shell, -or tooth, or bone, to that of some animal with which we are already -acquainted, is such that we are justified in inferring a corresponding -degree of likeness in the rest of the two organisms. It is on this -very simple principle, and not upon imaginary laws of physiological -correlation, about which, in most cases, we know nothing whatever, that -the so-called restorations of the palæontologist are based. - -Abundant illustrations of this truth will occur to every one who is -familiar with palæontology; none is more suitable than the case of the -so-called _Belemnites_. In the early days of the study of fossils, -this name was given to certain elongated stony bodies, ending at one -extremity in a conical point, and truncated at the other, which were -commonly reputed to be thunderbolts, and as such to have descended -from the sky. They are common enough in some parts of England; and, in -the condition in which they are ordinarily found, it might be difficult -to give satisfactory reasons for denying them to be merely mineral -bodies. - -They appear, in fact, to consist of nothing but concentric layers -of carbonate of lime, disposed in subcrystalline fibres, or prisms, -perpendicular to the layers. Among a great number of specimens of these -Belemnites, however, it was soon observed that some showed a conical -cavity at the blunt end; and, in still better preserved specimens, this -cavity appeared to be divided into chambers by delicate saucer-shaped -partitions, situated at regular intervals one above the other. Now -there is no mineral body which presents any structure comparable to -this, and the conclusion suggested itself that the Belemnites must be -the effects of causes other than those which are at work in inorganic -nature. On close examination, the saucer-shaped partitions were proved -to be all perforated at one point, and the perforations being situated -exactly in the same line, the chambers were seen to be traversed by -a canal, or _siphuncle_, which thus connected the smallest or apical -chamber with the largest. There is nothing like this in the vegetable -world; but an exactly corresponding structure is met with in the -shells of two kinds of existing animals, the pearly _Nautilus_ and -the _Spirula_, and only in them. These animals belong to the same -division—the _Cephalopoda_—as the cuttle-fish, the squid, and the -octopus. But they are the only existing members of the group which -possess chambered, siphunculated shells; and it is utterly impossible -to trace any physiological connection between the very peculiar -structural characters of a cephalopod and the presence of a chambered -shell. In fact, the squid has, instead of any such shell, a horny -“pen,” the cuttle-fish has the so-called “cuttle-bone,” and the octopus -has no shell, or, at most, a mere rudiment of one. - -Nevertheless, seeing that there is nothing in nature at all like the -chambered shell of the Belemnite, except the shells of the _Nautilus_ -and of the _Spirula_, it was legitimate to prophesy that the animal -from which the fossil proceeded must have belonged to the group of the -_Cephalopoda_. _Nautilus_ and _Spirula_ are both very rare animals, -but the progress of investigation brought to light the singular fact, -that, though each has the characteristic cephalopodous organisation, it -is very different from the other. The shell of _Nautilus_ is external, -that of _Spirula_ internal; _Nautilus_ has four gills, _Spirula_ -two; _Nautilus_ has multitudinous tentacles, _Spirula_ has only ten -arms beset with horny rimmed suckers; _Spirula_, like the squids and -cuttle-fishes, which it closely resembles, has a bag of ink which it -squirts out to cover its retreat when alarmed; _Nautilus_ has none. - -No amount of physiological reasoning could enable any one to say -whether the animal which fabricated the Belemnite was more like -_Nautilus_, or more like _Spirula_. But the accidental discovery of -Belemnites in due connection with black elongated masses which were -certainly fossilised ink-bags, inasmuch as the ink could be ground up -and used for painting as well as if it were recent sepia, settled the -question; and it became perfectly safe to prophesy that the creature -which fabricated the Belemnite was a two-gilled cephalopod with suckers -on its arms, and with all the other essential features of our living -squids, cuttle-fishes, and _Spirulæ_. The palæontologist was, by this -time, able to speak as confidently about the animal of the Belemnite, -as Zadig was respecting the queen’s spaniel. He could give a very fair -description of its external appearance, and even enter pretty fully -into the details of its internal organisation, and yet could declare -that neither he, nor any one else, had ever seen one. And as the -queen’s spaniel was found, so happily has the animal of the Belemnite; -a few exceptionally preserved specimens having been discovered, which -completely verify the retrospective prophecy of those who interpreted -the facts of the case by due application of the method of Zadig. - -These Belemnites flourished in prodigious abundance in the seas of the -mesozoic or secondary age of the world’s geological history; but no -trace of them has been found in any of the tertiary deposits, and they -appear to have died out towards the close of the mesozoic epoch. The -method of Zadig, therefore, applies in full force to the events of a -period which is immeasurably remote, which long preceded the origin -of the most conspicuous mountain masses of the present world, and -the deposition, at the bottom of the ocean, of the rocks which form -the greater part of the soil of our present continents. The Euphrates -itself, at the mouth of which Oannes landed, is a thing of yesterday -compared with a Belemnite; and even the liberal chronology of Magian -cosmogony fixes the beginning of the world only at a time when other -applications of Zadig’s method afford convincing evidence that, could -we have been there to see, things would have looked very much as they -do now. Truly the magi were wise in their generation; they foresaw -rightly that this pestilent application of the principles of common -sense, inaugurated by Zadig, would be their ruin. - -But it may be said that the method of Zadig, which is simple reasoning -from analogy, does not account for the most striking feats of modern -palæontology—the reconstruction of entire animals from a tooth or -perhaps a fragment of a bone; and it may be justly urged that Cuvier, -the great master of this kind of investigation, gave a very different -account of the process which yielded such remarkable results. - -Cuvier is not the first man of ability who has failed to make his -own mental processes clear to himself, and he will not be the last. -The matter can be easily tested. Search the eight volumes of the -“Recherches sur les Ossemens fossiles” from cover to cover, and -nothing but the application of the method of Zadig will be found in -the arguments by which a fragment of a skeleton is made to reveal the -characters of the animal to which it belonged. - -There is one well-known case which may represent all. It is an -excellent illustration of Cuvier’s sagacity, and he evidently takes -some pride in telling his story about it. A split slab of stone arrived -from the quarries of Montmartre, the two halves of which contained the -greater part of the skeleton of a small animal. On careful examinations -of the characters of the teeth and of the lower jaw, which happened -to be exposed, Cuvier assured himself that they presented such a very -close resemblance to the corresponding parts in the living opossums -that he at once assigned the fossil to that genus. - -Now the opossums are unlike most mammals in that they possess two -bones attached to the fore part of the pelvis, which are commonly -called “marsupial bones.” The name is a misnomer, originally conferred -because it was thought that these bones have something to do with the -support of the pouch, or marsupium, with which some, but not all, of -the opossums are provided. As a matter of fact, they have nothing to do -with the support of the pouch, and they exist as much in those opossums -which have no pouches as in those which possess them. In truth, no one -knows what the use of these bones may be, nor has any valid theory -of their physiological import yet been suggested. And if we have no -knowledge of the physiological importance of the bones themselves, it -is obviously absurd to pretend that we are able to give physiological -reasons why the presence of these bones is associated with certain -peculiarities of the teeth and of the jaws. If any one knows why four -molar teeth and an inflected angle of the jaw are very generally found -along with marsupial bones, he has not yet communicated that knowledge -to the world. - -If, however, Zadig was right in concluding from the likeness of the -hoof-prints which he observed to a horse’s that the creature which made -them had a tail like that of a horse, Cuvier, seeing that the teeth -and jaw of his fossil were just like those of an opossum, had the same -right to conclude that the pelvis would also be like an opossum’s; and -so strong was his conviction that this retrospective prophecy, about -an animal which he had never seen before, and which had been dead and -buried for millions of years, would be verified, that he went to work -upon the slab which contained the pelvis in confident expectation of -finding and laying bare the “marsupial bones,” to the satisfaction of -some persons whom he had invited to witness their disinterment. As -he says:—“Cette opération se fit en présence de quelques personnes à -qui j’en avais annoncé d’avance le résultat, dans l’intention de leur -prouver par le fait la justice de nos théories zoologiques; puisque le -vrai cachet d’une théorie est sans contredit la faculté qu’elle donne -de prévoir les phénomènes.” - -In the “Ossemens fossiles” Cuvier leaves his paper just as it first -appeared in the “Annales du Muséum,” as “a curious monument of the -force of zoological laws and of the use which may be made of them.” - -Zoological laws truly, but not physiological laws. If one sees a -live dog’s head, it is extremely probable that a dog’s tail is not -far off, though nobody can say why that sort of head and that sort -of tail go together; what physiological connection there is between -the two. So, in the case of the Montmartre fossil, Cuvier, finding a -thorough opossum’s head, concluded that the pelvis also would be like -an opossum’s. But, most assuredly, the most advanced physiologist of -the present day could throw no light on the question why these are -associated, nor could pretend to affirm that the existence of the one -is necessarily connected with that of the other. In fact, had it so -happened that the pelvis of the fossil had been originally exposed, -while the head lay hidden, the presence of the “marsupial bones,” -however like they might have been to an opossum’s, would by no means -have warranted the prediction that the skull would turn out to be that -of the opossum. It might just as well have been like that of some -other Marsupial; or even like that of the totally different group of -Monotremes, of which the only living representatives are the _Echidna_ -and the _Ornithorhynchus_. - -For all practical purposes, however, the empirical laws of -co-ordination of structures, which are embodied in the generalisations -of morphology, may be confidently trusted, if employed with due -caution, to lead to a just interpretation of fossil remains; or, in -other words, we may look for the verification of the retrospective -prophecies which are based upon them. - -And if this be the case, the late advances which have been made in -palæontological discovery open out a new field for such prophecies. -For it has been ascertained with respect to many groups of animals, -that, as we trace them back in time, their ancestors gradually cease -to exhibit those special modifications which at present characterise -the type, and more nearly embody the general plan of the group to which -they belong. - -Thus, in the well-known case of the horse, the toes which are -suppressed in the living horse are found to be more and more complete -in the older members of the group, until, at the bottom of the Tertiary -series of America, we find an equine animal which has four toes in -front and three behind. No remains of the horse tribe are at present -known from any Mesozoic deposit. Yet who can doubt that, whenever a -sufficiently extensive series of lacustrine and fluviatile beds of that -age becomes known, the lineage which has been traced thus far will be -continued by equine quadrupeds with an increasing number of digits, -until the horse type merges in the five-toed form towards which these -gradations point? - -But the argument which holds good for the horse, holds good, not only -for all mammals, but for the whole animal world. And as the study of -the pedigrees, or lines of evolution, to which, at present, we have -access, brings to light, as it assuredly will do, the laws of that -process, we shall be able to reason from the facts with which the -geological record furnishes us to those which have hitherto remained, -and many of which, perhaps, may for ever remain, hidden. The same -method of reasoning which enables us, when furnished with a fragment of -an extinct animal, to prophesy the character which the whole organism -exhibited, will, sooner or later, enable us, when we know a few of the -later terms of a genealogical series, to predict the nature of the -earlier terms. - -In no very distant future, the method of Zadig, applied to a greater -body of facts than the present generation is fortunate enough to -handle, will enable the biologist to reconstruct the scheme of life -from its beginning, and to speak as confidently of the character of -long extinct living beings, no trace of which has been preserved, as -Zadig did of the queen’s spaniel and the king’s horse. Let us hope that -they may be better rewarded for their toil and their sagacity than was -the Babylonian philosopher; for perhaps, by that time, the Magi also -may be reckoned among the members of a forgotten Fauna, extinguished in -the struggle for existence against their great rival, common sense. - - - - -VII. - -ON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE -VEGETABLE KINGDOMS. - - -In the whole history of science there is nothing more remarkable than -the rapidity of the growth of biological knowledge within the last -half-century, and the extent of the modification which has thereby been -effected in some of the fundamental conceptions of the naturalist. - -In the second edition of the “Règne Animal,” published in 1828, -Cuvier devotes a special section to the “Division of Organised Beings -into Animals and Vegetables,” in which the question is treated with -that comprehensiveness of knowledge and clear critical judgment -which characterise his writings, and justify us in regarding them -as representative expressions of the most extensive, if not the -profoundest, knowledge of his time. He tells us that living beings have -been subdivided from the earliest times into _animated beings_, which -possess sense and motion, and _inanimated beings_, which are devoid of -these functions, and simply vegetate. - -Although the roots of plants direct themselves towards moisture, and -their leaves towards air and light,—although the parts of some plants -exhibit oscillating movements without any perceptible cause, and the -leaves of others retract when touched,—yet none of these movements -justify the ascription to plants of perception or of will. From the -mobility of animals, Cuvier, with his characteristic partiality for -teleological reasoning, deduces the necessity of the existence in them -of an alimentary cavity, or reservoir of food, whence their nutrition -may be drawn by the vessels, which are a sort of internal roots; and, -in the presence of this alimentary cavity, he naturally sees the -primary and the most important distinction between animals and plants. - -Following out his teleological argument, Cuvier remarks that the -organisation of this cavity and its appurtenances must needs vary -according to the nature of the aliment, and the operations which it -has to undergo, before it can be converted into substances fitted for -absorption; while the atmosphere and the earth supply plants with -juices ready prepared, and which can be absorbed immediately. As the -animal body required to be independent of heat and of the atmosphere, -there were no means by which the motion of its fluids could be produced -by internal causes. Hence arose the second great distinctive character -of animals, or the circulatory system, which is less important than the -digestive, since it was unnecessary, and therefore is absent, in the -more simple animals. - -Animals further needed muscles for locomotion and nerves for -sensibility. Hence, says Cuvier, it was necessary that the chemical -composition of the animal body should be more complicated than that of -the plant; and it is so, inasmuch as an additional substance, nitrogen, -enters into it as an essential element; while, in plants, nitrogen is -only accidentally joined with the three other fundamental constituents -of organic beings—carbon, hydrogen, and oxygen. Indeed, he afterwards -affirms that nitrogen is peculiar to animals; and herein he places the -third distinction between the animal and the plant. The soil and the -atmosphere supply plants with water, composed of hydrogen and oxygen; -air, consisting of nitrogen and oxygen; and carbonic acid, containing -carbon and oxygen. They retain the hydrogen and the carbon, exhale the -superfluous oxygen, and absorb little or no nitrogen. The essential -character of vegetable life is the exhalation of oxygen, which is -effected through the agency of light. Animals, on the contrary, -derive their nourishment either directly or indirectly from plants. -They get rid of the superfluous hydrogen and carbon, and accumulate -nitrogen. The relations of plants and animals to the atmosphere are -therefore inverse. The plant withdraws water and carbonic acid from -the atmosphere, the animal contributes both to it. Respiration—that -is, the absorption of oxygen and the exhalation of carbonic acid—is -the specially animal function of animals, and constitutes their fourth -distinctive character. - -Thus wrote Cuvier in 1828. But, in the fourth and fifth decades of -this century, the greatest and most rapid revolution which biological -science has ever undergone was effected by the application of the -modern microscope to the investigation of organic structure; by the -introduction of exact and easily manageable methods of conducting the -chemical analysis of organic compounds; and finally, by the employment -of instruments of precision for the measurement of the physical forces -which are at work in the living economy. - -That the semi-fluid contents (which we now term protoplasm) of the -cells of certain plants, such as the _Charæ_, are in constant and -regular motion, was made out by Bonaventura Corti a century ago; but -the fact, important as it was, fell into oblivion, and had to be -rediscovered by Treviranus in 1807. Robert Brown noted the more complex -motions of the protoplasm in the cells of _Tradescantia_ in 1831; and -now such movements of the living substance of plants are well known to -be some of the most widely-prevalent phenomena of vegetable life. - -Agardh, and other of the botanists of Cuvier’s generation, who occupied -themselves with the lower plants, had observed that, under particular -circumstances, the contents of the cells of certain water-weeds were -set free, and moved about with considerable velocity, and with all the -appearances of spontaneity, as locomotive bodies, which, from their -similarity to animals of simple organisation, were called “zoospores.” -Even as late as 1845, however, a botanist of Schleiden’s eminence dealt -very sceptically with these statements; and his scepticism was the more -justified, since Ehrenberg, in his elaborate and comprehensive work -on the _Infusoria_, had declared the greater number of what are now -recognised as locomotive plants to be animals. - -At the present day, innumerable plants and free plant cells are known -to pass the whole or part of their lives in an actively locomotive -condition, in no wise distinguishable from that of one of the simpler -animals; and, while in this condition, their movements are, to all -appearance, as spontaneous—as much the product of volition—as those of -such animals. - -Hence the teleological argument for Cuvier’s first diagnostic -character—the presence in animals of an alimentary cavity, or internal -pocket, in which they can carry about their nutriment—has broken -down, so far, at least, as his mode of stating it goes. And, with the -advance of microscopic anatomy, the universality of the fact itself -among animals has ceased to be predicable. Many animals of even complex -structure, which live parasitically within others, are wholly devoid -of an alimentary cavity. Their food is provided for them, not only -ready cooked, but ready digested, and the alimentary canal, become -superfluous, has disappeared. Again, the males of most Rotifers have no -digestive apparatus; as a German naturalist has remarked, they devote -themselves entirely to the “Minnedienst,” and are to be reckoned among -the few realisations of the Byronic ideal of a lover. Finally, amidst -the lowest forms of animal life, the speck of gelatinous protoplasm, -which constitutes the whole body, has no permanent digestive cavity or -mouth, but takes in its food anywhere; and digests, so to speak, all -over its body. - -But although Cuvier’s leading diagnosis of the animal from the plant -will not stand a strict test, it remains one of the most constant of -the distinctive characters of animals. And, if we substitute for the -possession of an alimentary cavity, the power of taking solid nutriment -into the body and there digesting it, the definition so changed -will cover all animals, except certain parasites, and the few and -exceptional cases of non-parasitic animals which do not feed at all. On -the other hand, the definition thus amended will exclude all ordinary -vegetable organisms. - -Cuvier himself practically gives up his second distinctive mark when he -admits that it is wanting in the simpler animals. - -The third distinction is based on a completely erroneous conception of -the chemical differences and resemblances between the constituents of -animal and vegetable organisms, for which Cuvier is not responsible, -as it was current among contemporary chemists. It is now established -that nitrogen is as essential a constituent of vegetable as of animal -living matter; and that the latter is, chemically speaking, just as -complicated as the former. Starchy substances, cellulose and sugar, -once supposed to be exclusively confined to plants, are now known to -be regular and normal products of animals. Amylaceous and saccharine -substances are largely manufactured, even by the highest animals; -cellulose is widespread as a constituent of the skeletons of the lower -animals; and it is probable that amyloid substances are universally -present in the animal organism, though not in the precise form of -starch. - -Moreover, although it remains true that there is an inverse relation -between the green plant in sunshine and the animal, in so far as, under -these circumstances, the green plant decomposes carbonic acid and -exhales oxygen, while the animal absorbs oxygen and exhales carbonic -acid; yet, the exact researches of the modern chemical investigators -of the physiological processes of plants have clearly demonstrated the -fallacy of attempting to draw any general distinction between animals -and vegetables on this ground. In fact, the difference vanishes with -the sunshine, even in the case of the green plant; which, in the dark, -absorbs oxygen and gives out carbonic acid like any animal.[30] On -the other hand, those plants, such as the fungi, which contain no -chlorophyll and are not green, are always, so far as respiration is -concerned, in the exact position of animals. They absorb oxygen and -give out carbonic acid. - -Thus, by the progress of knowledge, Cuvier’s fourth distinction -between the animal and the plant has been as completely invalidated as -the third and second; and even the first can be retained only in a -modified form and subject to exceptions. - -But has the advance of biology simply tended to break down old -distinctions, without establishing new ones? - -With a qualification, to be considered presently, the answer to this -question is undoubtedly in the affirmative. The famous researches of -Schwann and Schleiden in 1837 and the following years, founded the -modern science of histology, or that branch of anatomy which deals -with the ultimate visible structure of organisms, as revealed by -the microscope; and, from that day to this, the rapid improvement -of methods of investigation, and the energy of a host of accurate -observers, have given greater and greater breadth and firmness to -Schwann’s great generalisation, that a fundamental unity of structure -obtains in animals and plants; and that, however diverse may be the -fabrics, or _tissues_, of which their bodies are composed, all these -varied structures result from the metamorphosis of morphological units -(termed _cells_, in a more general sense than that in which the word -“cells” was at first employed), which are not only similar in animals -and in plants respectively, but present a close resemblance, when those -of animals and those of plants are compared together. - -The contractility which is the fundamental condition of locomotion, -has not only been discovered to exist far more widely among plants -than was formerly imagined; but, in plants, the act of contraction has -been found to be accompanied, as Dr. Burdon Sanderson’s interesting -investigations have shown, by a disturbance of the electrical state of -the contractile substance, comparable to that which was found by Du -Bois Reymond to be a concomitant of the activity of ordinary muscle in -animals. - -Again, I know of no test by which the reaction of the leaves of the -Sundew and of other plants to stimuli, so fully and carefully studied -by Mr. Darwin, can be distinguished from those acts of contraction -following upon stimuli, which are called “reflex” in animals. - -On each lobe of the bilobed leaf of Venus’s fly trap (_Dionæa -muscipula_) are three delicate filaments which stand out at right angle -from the surface of the leaf. Touch one of them with the end of a fine -human hair and the lobes of the leaf instantly close together[31] in -virtue of an act of contraction of part of their substance, just as the -body of a snail contracts into its shell when one of its “horns” is -irritated. - -The reflex action of the snail is the result of the presence of a -nervous system in the animal. A molecular change takes place in the -nerve of the tentacle, is propagated to the muscles by which the body -is retracted, and causing them to contract, the act of retraction -is brought about. Of course the similarity of the acts does not -necessarily involve the conclusion that the mechanism by which they are -effected is the same; but it suggests a suspicion of their identity -which needs careful testing. - -The results of recent inquiries into the structure of the nervous -system of animals converge towards the conclusion that the nerve -fibres, which we have hitherto regarded as ultimate elements of nervous -tissue, are not such, but are simply the visible aggregations of vastly -more attenuated filaments, the diameter of which dwindles down to the -limits of our present microscopic vision, greatly as these have been -extended by modern improvements of the microscope; and that a nerve -is, in its essence, nothing but a linear tract of specially modified -protoplasm between two points of an organism—one of which is able to -affect the other by means of the communication so established. Hence, -it is conceivable that even the simplest living being may possess a -nervous system. And the question whether plants are provided with a -nervous system or not, thus acquires a new aspect, and presents the -histologist and physiologist with a problem of extreme difficulty, -which must be attacked from a new point of view and by the aid of -methods which have yet to be invented. - -Thus it must be admitted that plants may be contractile and locomotive; -that, while locomotive, their movements may have as much appearance -of spontaneity as those of the lowest animals; and that many exhibit -actions, comparable to those which are brought about by the agency of a -nervous system in animals. And it must be allowed to be possible that -further research may reveal the existence of something comparable to a -nervous system in plants. So that I know not where we can hope to find -any absolute distinction between animals and plants, unless we return -to their mode of nutrition, and inquire whether certain differences of -a more occult character than those imagined to exist by Cuvier, and -which certainly hold good for the vast majority of animals and plants, -are of universal application. - -A bean may be supplied with water in which salts of ammonia and -certain other mineral salts are dissolved in due proportion; with -atmospheric air containing its ordinary minute dose of carbonic acid; -and with nothing else but sunlight and heat. Under these circumstances, -unnatural as they are, with proper management, the bean will thrust -forth its radicle and its plumule; the former will grow down into -roots, the latter grow up into the stem and leaves of a vigorous bean -plant; and this plant will, in due time, flower and produce its crop of -beans, just as if it were grown in the garden or in the field. - -The weight of the nitrogenous protein compounds, of the oily, starchy, -saccharine and woody substances contained in the full-grown plant -and its seeds, will be vastly greater than the weight of the same -substances contained in the bean from which it sprang. But nothing has -been supplied to the bean save water, carbonic acid, ammonia, potash, -lime, iron, and the like, in combination with phosphoric, sulphuric, -and other acids. Neither protein, nor fat, nor starch, nor sugar, nor -any substance in the slightest degree resembling them, has formed part -of the food of the bean. But the weights of the carbon, hydrogen, -oxygen, nitrogen, phosphorus, sulphur, and other elementary bodies -contained in the bean-plant, and in the seeds which it produces, are -exactly equivalent to the weights of the same elements which have -disappeared from the materials supplied to the bean during its growth. -Whence it follows that the bean has taken in only the raw materials of -its fabric, and has manufactured them into bean stuffs. - -The bean has been able to perform this great chemical feat by the -help of its green colouring matter, or chlorophyll; for it is only -the green parts of the plant which, under the influence of sunlight, -have the marvellous power of decomposing carbonic acid, setting free -the oxygen and laying hold of the carbon which it contains. In fact, -the bean obtains two of the absolutely indispensable elements of its -substance from two distinct sources; the watery solution, in which its -roots are plunged, contains nitrogen but no carbon; the air, to which -the leaves are exposed, contains carbon, but its nitrogen is in the -state of a free gas, in which condition the bean can make no use of -it;[32] and the chlorophyll[33] is the apparatus by which the carbon is -extracted from the atmospheric carbonic acid—the leaves being the chief -laboratories in which this operation is effected. - -The great majority of conspicuous plants are, as everybody knows, -green; and this arises from the abundance of their chlorophyll. -The few which contain no chlorophyll and are colourless, are unable -to extract the carbon which they require from atmospheric carbonic -acid, and lead a parasitic existence upon other plants; but it by no -means follows, often as the statement has been repeated, that the -manufacturing power of plants depends on their chlorophyll, and its -interaction with the rays of the sun. On the contrary, it is easily -demonstrated, as Pasteur first proved, that the lowest fungi, devoid -of chlorophyll, or of any substitute for it, as they are, nevertheless -possess the characteristic manufacturing powers of plants in a very -high degree. Only it is necessary that they should be supplied with -a different kind of raw material; as they cannot extract carbon from -carbonic acid, they must be furnished with something else that contains -carbon. Tartaric acid is such a substance; and if a single spore of -the commonest and most troublesome of moulds—_Penicillium_—be sown -in a saucerful of water, in which tartrate of ammonia, with a small -percentage of phosphates and sulphates is contained, and kept warm, -whether in the dark or exposed to light, it will, in a short time, give -rise to a thick crust of mould, which contains many million times the -weight of the original spore, in protein compounds and cellulose. Thus -we have a very wide basis of fact for the generalisation that plants -are essentially characterised by their manufacturing capacity—by their -power of working up mere mineral matters into complex organic compounds. - -Contrariwise, there is a no less wide foundation for the -generalisation that animals, as Cuvier puts it, depend directly or -indirectly upon plants for the materials of their bodies; that is, -either they are herbivorous, or they eat other animals which are -herbivorous. - -But for what constituents of their bodies are animals thus dependent -upon plants? Certainly not for their horny matter; nor for chondrin, -the proximate chemical element of cartilage; nor for gelatine; nor for -syntonin, the constituent of muscle; nor for their nervous or biliary -substances; nor for their amyloid matters; nor, necessarily, for their -fats. - -It can be experimentally demonstrated that animals can make these for -themselves. But that which they cannot make, but must, in all known -cases, obtain directly or indirectly from plants, is the peculiar -nitrogenous matter, protein. Thus the plant is the ideal _prolétaire_ -of the living world, the worker who produces; the animal, the ideal -aristocrat, who mostly occupies himself in consuming, after the manner -of that noble representative of the line of Zähdarm, whose epitaph is -written in _Sartor Resartus_. - -Here is our last hope of finding a sharp line of demarcation between -plants and animals; for, as I have already hinted, there is a border -territory between the two kingdoms, a sort of no-man’s-land, the -inhabitants of which certainly cannot be discriminated and brought to -their proper allegiance in any other way. - -Some months ago, Professor Tyndall asked me to examine a drop of -infusion of hay, placed under an excellent and powerful microscope, -and to tell him what I thought some organisms visible in it were. -I looked and observed, in the first place, multitudes of _Bacteria_ -moving about with their ordinary intermittent spasmodic wriggles. As -to the vegetable nature of these there is now no doubt. Not only does -the close resemblance of the _Bacteria_ to unquestionable plants, -such as the _Oscillatoriæ_, and lower forms of _Fungi_, justify this -conclusion, but the manufacturing test settles the question at once. It -is only needful to add a minute drop of fluid containing _Bacteria_, -to water in which tartrate, phosphate, and sulphate of ammonia are -dissolved; and, in a very short space of time, the clear fluid becomes -milky by reason of their prodigious multiplication, which, of course, -implies the manufacture of living Bacterium-stuff out of these merely -saline matters. - -But other active organisms, very much larger than the _Bacteria_, -attaining in fact the comparatively gigantic dimensions of 1/3000 of an -inch or more, incessantly crossed the field of view. Each of these had -a body shaped like a pear, the small end being slightly incurved and -produced into a long curved filament, or _cilium_, of extreme tenuity. -Behind this, from the concave side of the incurvation, proceeded -another long cilium, so delicate as to be discernible only by the use -of the highest powers and careful management of the light. In the -centre of the pear-shaped body a clear round space could occasionally -be discerned, but not always; and careful watching showed that this -clear vacuity appeared gradually, and then shut up and disappeared -suddenly, at regular intervals. Such a structure is of common -occurrence among the lowest plants and animals, and is known as a -_contractile vacuole_. - -The little creature thus described sometimes propelled itself with -great activity, with a curious rolling motion, by the lashing of the -front cilium, while the second cilium trailed behind; sometimes it -anchored itself by the hinder cilium and was spun round by the working -of the other, its motions resembling those of an anchor buoy in a heavy -sea. Sometimes, when two were in full career towards one another, each -would appear dexterously to get out of the other’s way; sometimes a -crowd would assemble and jostle one another, with as much semblance of -individual effort as a spectator on the Grands Mulets might observe -with a telescope among the specks representing men in the valley of -Chamounix. - -The spectacle, though always surprising, was not new to me. So my -reply to the question put to me was, that these organisms were what -biologists call _Monads_, and though they might be animals, it was -also possible that they might, like the _Bacteria_, be plants. My -friend received my verdict with an expression which showed a sad want -of respect for authority. He would as soon believe that a sheep was -a plant. Naturally piqued by this want of faith, I have thought a -good deal over the matter; and as I still rest in the lame conclusion -I originally expressed, and must even now confess that I cannot -certainly say whether this creature is an animal or a plant, I think -it may be well to state the grounds of my hesitation at length. But, -in the first place, in order that I may conveniently distinguish -this “Monad” from the multitude of other things which go by the same -designation, I must give it a name of its own. I think (though, for -reasons which need not be stated at present, I am not quite sure) -that it is identical with the species _Monas lens_, as defined by the -eminent French microscopist Dujardin, though his magnifying power was -probably insufficient to enable him to see that it is curiously like -a much larger form of monad which he has named _Heteromita_. I shall, -therefore, call it not _Monas_, but _Heteromita lens_. - -I have been unable to devote to my _Heteromita_ the prolonged study -needful to work out its whole history, which would involve weeks, or -it may be months, of unremitting attention. But I the less regret this -circumstance, as some remarkable observations recently published by -Messrs. Dallinger and Drysdale[34] on certain Monads, relate, in part, -to a form so similar to my _Heteromita lens_, that the history of the -one may be used to illustrate that of the other. These most patient -and painstaking observers, who employed the highest attainable powers -of the microscope and, relieving one another, kept watch day and night -over the same individual monads, have been enabled to trace out the -whole history of their _Heteromita_; which they found in infusions of -the heads of fishes of the Cod tribe. - -Of the four monads described and figured by these investigators, -one, as I have said, very closely resembles _Heteromita lens_ in -every particular, except that it has a separately distinguishable -central particle or “nucleus,” which is not certainly to be made out -in _Heteromita lens_; and that nothing is said by Messrs. Dallinger -and Drysdale of the existence of a contractile vacuole in this monad, -though they describe it in another. - -Their _Heteromita_, however, multiplied rapidly by fission. Sometimes -a transverse constriction appeared; the hinder half developed a new -cilium, and the hinder cilium gradually split from its base to its -free end, until it was divided into two; a process which, considering -the fact that this fine filament cannot be much more than 1/100000 -of an inch in diameter, is wonderful enough. The constriction of the -body extended inwards until the two portions were united by a narrow -isthmus; finally, they separated and each swam away by itself, a -complete _Heteromita_, provided with its two cilia. Sometimes the -constriction took a longitudinal direction, with the same ultimate -result. In each case the process occupied not more than six or seven -minutes. At this rate, a single _Heteromita_ would give rise to a -thousand like itself in the course of an hour, to about a million in -two hours, and to a number greater than the generally assumed number -of human beings now living in the world in three hours; or, if we give -each _Heteromita_ an hour’s enjoyment of individual existence, the same -result will be obtained in about a day. The apparent suddenness of the -appearance of multitudes of such organisms as these, in any nutritive -fluid to which one obtains access, is thus easily explained. - -During these processes of multiplication by fission, the _Heteromita_ -remains active; but sometimes another mode of fission occurs. The body -becomes rounded and quiescent, or nearly so; and, while in this resting -state, divides into two portions, each of which is rapidly converted -into an active _Heteromita_. - -A still more remarkable phenomenon is that kind of multiplication -which is preceded by the union of two monads, by a process which is -termed _conjugation_. Two active _Heteromitæ_ become applied to one -another, and then slowly and gradually coalesce into one body. The -two nuclei run into one; and the mass resulting from the conjugation -of the two _Heteromitæ_, thus fused together, has a triangular form. -The two pairs of cilia are to be seen, for some time, at two of the -angles, which answer to the small ends of the conjoined monads; but -they ultimately vanish, and the twin organism, in which all visible -traces of organisation have disappeared, falls into a state of rest. -Sudden wave-like movements of its substance next occur; and, in a short -time, the apices of the triangular mass burst, and give exit to a dense -yellowish, glairy fluid, filled with minute granules. This process, -which, it will be observed, involves the actual confluence and mixture -of the substance of two distinct organisms, is effected in the space of -about two hours. - -The authors whom I quote say that they “cannot express” the excessive -minuteness of the granules in question, and they estimate their -diameter at less than 1/200000 of an inch. Under the highest powers -of the microscope at present applicable such specks are hardly -discernible. Nevertheless, particles of this size are massive when -compared to physical molecules; whence there is no reason to doubt -that each, small as it is, may have a molecular structure sufficiently -complex to give rise to the phenomena of life. And, as a matter of -fact, by patient watching of the place at which these infinitesimal -living particles were discharged, our observers assured themselves -of their growth and development into new monads. These, in about -four hours from their being set free, had attained a sixth of the -length of the parent, with the characteristic cilia, though at -first they were quite motionless; and, in four hours more, they had -attained the dimensions and exhibited all the activity of the adult. -These inconceivably minute particles are therefore the germs of the -_Heteromita_; and from the dimensions of these germs it is easily -shown that the body formed by conjugation may, at a low estimate, -have given exit to thirty thousand of them; a result of a matrimonial -process whereby the contracting parties, without a metaphor, “become -one flesh,” enough to make a Malthusian despair of the future of the -Universe. - -I am not aware that the investigators from whom I have borrowed this -history have endeavoured to ascertain whether their monads take solid -nutriment or not; so that though they help us very much to fill up the -blanks in the history of my _Heteromita_, their observations throw no -light on the problem we are trying to solve—Is it an animal or is it a -plant? - -Undoubtedly it is possible to bring forward very strong arguments in -favour of regarding _Heteromita_ as a plant. - -For example, there is a Fungus, an obscure and almost microscopic -mould, termed _Peronospora infestans_. Like many other Fungi, the -_Peronosporæ_ are parasitic upon other plants; and this particular -_Peronospora_ happens to have attained much notoriety and political -importance, in a way not without a parallel in the career of notorious -politicians, namely, by reason of the frightful mischief it has -done to mankind. For it is this _Fungus_ which is the cause of the -potato disease; and, therefore, _Peronospora infestans_ (doubtless of -exclusively Saxon origin, though not accurately known to be so) brought -about the Irish famine. The plants afflicted with the malady are found -to be infested by a mould, consisting of fine tubular filaments, termed -_hyphæ_, which burrow through the substance of the potato plant, and -appropriate to themselves the substance of their host; while, at the -same time, directly or indirectly, they set up chemical changes by -which even its woody framework becomes blackened, sodden, and withered. - -In structure, however, the _Peronospora_ is as much a mould as the -common _Penicillium_; and just as the _Penicillium_ multiplies by the -breaking up of its hyphæ into separate rounded bodies, the spores; -so, in the _Peronospora_, certain of the hyphæ grow out into the air -through the interstices of the superficial cells of the potato plant, -and develop spores. Each of these hyphæ usually gives off several -branches. The ends of the branches dilate and become closed sacs, which -eventually drop off as spores. The spores falling on some part of the -same potato plant, or carried by the wind to another, may at once -germinate, throwing out tubular prolongations which become hyphæ, and -burrow into the substance of the plant attacked. But, more commonly, -the contents of the spore divide into six or eight separate portions. -The coat of the spore gives way, and each portion then emerges as an -independent organism, which has the shape of a bean, rather narrower at -one end than the other, convex on one side, and depressed or concave on -the opposite. From the depression, two long and delicate cilia proceed, -one shorter than the other, and directed forwards. Close to the origin -of these cilia, in the substance of the body, is a regularly pulsating, -contractile vacuole. The shorter cilium vibrates actively, and effects -the locomotion of the organism, while the other trails behind; the -whole body rolling on its axis with its pointed end forwards. - -The eminent botanist, De Bary, who was not thinking of our problem, -tells us, in describing the movements of these “Zoospores,” that, as -they swim about, “Foreign bodies are carefully avoided, and the whole -movement has a deceptive likeness to the voluntary changes of place -which are observed in microscopic animals.” - -After swarming about in this way in the moisture on the surface of -a leaf or stem (which, film though it may be, is an ocean to such a -fish) for half an hour, more or less, the movement of the zoospore -becomes slower, and is limited to a slow turning upon its axis, without -change of place. It then becomes quite quiet, the cilia disappear, it -assumes a spherical form, and surrounds itself with a distinct, though -delicate, membranous coat. A protuberance then grows out from one side -of the sphere, and rapidly increasing in length, assumes the character -of a hypha. The latter penetrates into the substance of the potato -plant, either by entering a stomate, or by boring through the wall of -an epidermic cell, and ramifies, as a mycelium, in the substance of -the plant, destroying the tissues with which it comes in contact. As -these processes of multiplication take place very rapidly, millions of -spores are soon set free from a single infested plant; and, from their -minuteness, they are readily transported by the gentlest breeze. Since, -again, the zoospores set free from each spore, in virtue of their -powers of locomotion, swiftly disperse themselves over the surface, it -is no wonder that the infection, once started, soon spreads from field -to field, and extends its ravages over a whole country. - -However, it does not enter into my present plan to treat of the -potato disease, instructively as its history bears upon that of other -epidemics; and I have selected the case of the _Peronospora_ simply -because it affords an example of an organism, which, in one stage of -its existence, is truly a “Monad,” indistinguishable by any important -character from our _Heteromita_, and extraordinarily like it in some -respects. And yet this “Monad” can be traced, step by step, through the -series of metamorphoses which I have described, until it assumes the -features of an organism, which is as much a plant as is an oak or an -elm. - -Moreover, it would be possible to pursue the analogy farther. Under -certain circumstances, a process of conjugation takes place in the -_Peronospora_. Two separate portions of its protoplasm become fused -together, surround themselves with a thick coat, and give rise to a -sort of vegetable egg called an _oospore_. After a period of rest, -the contents of the oospore break up into a number of zoospores like -those already described, each of which, after a period of activity, -germinates in the ordinary way. This process obviously corresponds -with the conjugation and subsequent setting free of germs in the -_Heteromita_. - -But it may be said that the _Peronospora_ is, after all, a questionable -sort of plant; that it seems to be wanting in the manufacturing power, -selected as the main distinctive character of vegetable life; or, at -any rate, that there is no proof that it does not get its protein -matter ready made from the potato plant. - -Let us, therefore, take a case which is not open to these objections. - -There are some small plants known to botanists as members of the genus -_Coleochæte_, which, without being truly parasitic, grow upon certain -water-weeds, as lichens grow upon trees. The little plant has the form -of an elegant green star, the branching arms of which are divided into -cells. Its greenness is due to its chlorophyll, and it undoubtedly -has the manufacturing power in full degree, decomposing carbonic acid -and setting oxygen free, under the influence of sunlight. But the -protoplasmic contents of some of the cells of which the plant is made -up occasionally divide, by a method similar to that which effects the -division of the contents of the _Peronospora_ spore; and the severed -portions are then set free as active monad-like zoospores. Each is oval -and is provided at one extremity with two long active cilia. Propelled -by these, it swims about for a longer or shorter time, but at length -comes to a state of rest and gradually grows into a _Coleochæte_. -Moreover, as in the _Peronospora_, conjugation may take place and -result in an oospore; the contents of which divide and are set free as -monadiform germs. - -If the whole history of the zoospores of _Peronospora_, and of -_Coleochæte_ were unknown, they would undoubtedly be classed among -“Monads” with the same right as _Heteromita_; why then may not -_Heteromita_ be a plant, even though the cycle of forms through -which it passes shows no terms quite so complex as those which occur -in _Peronospora_ and _Coleochæte_? And, in fact, there are some -green organisms, in every respect characteristically plants, such -as _Chlamydomonas_, and the common _Volvox_, or so-called “Globe -animalcule,” which run through a cycle of forms of just the same simple -character as those of _Heteromita_. - -The name of _Chlamydomonas_ is applied to certain microscopic green -bodies, each of which consists of a protoplasmic central substance -invested by a structureless sac. The latter contains cellulose, as -in ordinary plants; and the chlorophyll which gives the green colour -enables the _Chlamydomonas_ to decompose carbonic acid and fix carbon -as they do. Two long cilia protrude through the cell-wall, and effect -the rapid locomotion of this “monad,” which, in all respects except its -mobility, is characteristically a plant. Under ordinary circumstances, -the _Chlamydomonas_ multiplies by simple fission, each splitting -into two or into four parts, which separate and become independent -organisms. Sometimes, however, the _Chlamydomonas_ divides into eight -parts, each of which is provided with four instead of two cilia. These -“zoospores” conjugate in pairs, and give rise to quiescent bodies, -which multiply by division, and eventually pass into the active state. - -Thus, so far as outward form and the general character of the cycle -of modifications, through which the organism passes in the course of -its life, are concerned, the resemblance between _Chlamydomonas_ and -_Heteromita_ is of the closest description. And on the face of the -matter there is no ground for refusing to admit that _Heteromita_ may -be related to _Chlamydomonas_, as the colourless fungus is to the green -alga. _Volvox_ may be compared to a hollow sphere, the wall of which -is made up of coherent Chlamydomonads; and which progresses with a -rotating motion effected by the paddling of the multitudinous pairs of -cilia which project from its surface. Each _Volvox_monad, moreover, -possesses a red pigment spot, like the simplest form of eye known among -animals. The methods of fissive multiplication and of conjugation -observed in the monads of this locomotive globe are essentially similar -to those observed in _Chlamydomonas_; and, though a hard battle has -been fought over it, _Volvox_ is now finally surrendered to the -Botanists. - -Thus there is really no reason why _Heteromita_ may not be a plant; and -this conclusion would be very satisfactory, if it were not equally easy -to show that there is really no reason why it should not be an animal. -For there are numerous organisms presenting the closest resemblance to -_Heteromita_, and, like it, grouped under the general name of “Monads,” -which, nevertheless, can be observed to take in solid nutriment, and -which, therefore, have a virtual, if not an actual, mouth and digestive -cavity, and thus come under Cuvier’s definition of an animal. Numerous -forms of such animals have been described by Ehrenberg, Dujardin, H. -James Clark, and other writers on the _Infusoria_. Indeed, in another -infusion of hay in which my _Heteromita lens_ occurred, there were -innumerable infusorial animalcules belonging to the well-known species -_Colpoda cucullus_.[35] - -Full-sized specimens of this animalcule attain a length of between -1/300 or 1/400 of an inch, so that it may have ten times the length -and a thousand times the mass of a _Heteromita_. In shape, it is -not altogether unlike _Heteromita_. The small end, however, is not -produced into one long cilium, but the general surface of the body is -covered with small actively vibrating ciliary organs, which are only -longest at the small end. At the point which answers to that from which -the two cilia arise in _Heteromita_, there is a conical depression, the -mouth; and, in young specimens, a tapering filament, which reminds one -of the posterior cilium of _Heteromita_, projects from this region. - -The body consists of a soft granular protoplasmic substance, the middle -of which is occupied by a large oval mass called the “nucleus;” while, -at its hinder end, is a “contractile vacuole,” conspicuous by its -regular rhythmic appearances and disappearances. Obviously, although -the _Colpoda_ is not a monad, it differs from one only in subordinate -details. Moreover, under certain conditions, it becomes quiescent, -incloses itself in a delicate case or _cyst_, and then divides into -two, four, or more portions, which are eventually set free and swim -about as active _Colpodæ_. - -But this creature is an unmistakable animal, and full-sized _Colpodæ_ -may be fed as easily as one feeds chickens. It is only needful to -diffuse very finely ground carmine through the water in which they -live, and, in a very short time, the bodies of the _Colpodæ_ are -stuffed with the deeply-coloured granules of the pigment. - -And if this were not sufficient evidence of the animality of _Colpoda_, -there comes the fact that it is even more similar to another well-known -animalcule, _Paramæcium_, than it is to a monad. But _Paramæcium_ is -so huge a creature compared with those hitherto discussed—it reaches -1/120 of an inch or more in length—that there is no difficulty in -making out its organisation in detail; and in proving that it is not -only an animal, but that it is an animal which possesses a somewhat -complicated organisation. For example, the surface layer of its body is -different in structure from the deeper parts. There are two contractile -vacuoles, from each of which radiates a system of vessel-like canals; -and not only is there a conical depression continuous with a tube, -which serve as mouth and gullet, but the food ingested takes a definite -course, and refuse is rejected from a definite region. Nothing is -easier than to feed these animals, and to watch the particles of indigo -or carmine accumulate at the lower end of the gullet. From this they -gradually project, surrounded by a ball of water, which at length -passes with a jerk, oddly simulating a gulp, into the pulpy central -substance of the body, there to circulate up one side and down the -other, until its contents are digested and assimilated. Nevertheless, -this complex animal multiplies by division, as the monad does, and, -like the monad, undergoes conjugation. It stands in the same relation -to _Heteromita_ on the animal side, as _Coleochæte_ does on the plant -side. Start from either, and such an insensible series of gradations -leads to the monad that it is impossible to say at any stage of the -progress—here the line between the animal and the plant must be drawn. - -There is reason to think that certain organisms which pass through a -monad stage of existence, such as the _Myxomycetes_, are, at one time -of their lives, dependent upon external sources for their protein -matter, or are animals; and, at another period, manufacture it, or are -plants. And seeing that the whole progress of modern investigation is -in favour of the doctrine of continuity, it is a fair and probable -speculation—though only a speculation—that, as there are some plants -which can manufacture protein out of such apparently intractable -mineral matters as carbonic acid, water, nitrate of ammonia, metallic -and earthy salts; while others need to be supplied with their carbon -and nitrogen in the somewhat less raw form of tartrate of ammonia and -allied compounds; so there may be yet others, as is possibly the case -with the true parasitic plants, which can only manage to put together -materials still better prepared—still more nearly approximated to -protein—until we arrive at such organisms as the _Psorospermiæ_ and the -_Panhistophyton_, which are as much animal as vegetable in structure, -but are animal in their dependence on other organisms for their food. - -The singular circumstance observed by Meyer, that the _Torula_ of -yeast, though an indubitable plant, still flourishes most vigorously -when supplied with the complex nitrogenous substance, pepsin; the -probability that the _Peronospora_ is nourished directly by the -protoplasm of the potato-plant; and the wonderful facts which have -recently been brought to light respecting insectivorous plants, all -favour this view; and tend to the conclusion that the difference -between animal and plant is one of degree rather than of kind; and that -the problem whether, in a given case, an organism is an animal or a -plant, may be essentially insoluble. - - - - -VIII. - -ON CERTAIN ERRORS RESPECTING THE STRUCTURE OF THE HEART -ATTRIBUTED TO ARISTOTLE. - - -In all the commentaries upon the “Historia Animalium” which I have met -with, Aristotle’s express and repeated statement, that the heart of -man and the largest animals contains only three cavities, is noted as -a remarkable error. Even Cuvier, who had a great advantage over most -of the commentators in his familiarity with the subject of Aristotle’s -description, and whose habitual caution and moderation seem to desert -him when the opportunity of panegyrising the philosopher presents -itself, is betrayed into something like a sneer on this topic. - - “Du reste il n’attribue à cet organe que trois cavités, - erreur qui prouve au moins qu’il en avait regardé la - structure.”[36] - -To which remark, what follows will, I think, justify the reply, that it -“prouve au moins” that Cuvier had not given ordinary attention, to say -nothing of the careful study which they deserve, to sundry passages in -the first and the third books of the “Historia” which I proceed to lay -before the reader. - -For convenience of reference these passages are marked _A_, _B_, _C_, -etc.[37] - - Book i. 17.—(_A_) “The heart has three cavities, it lies - above the lung on the division of the windpipe, and has - a fatty and thick membrane where it is united with the - great vein and the aorta. It lies upon the aorta, with - its point down the chest, in all animals that have a - chest. In all, alike in those that have a chest and in - those that have none, the foremost part of it is the - apex. This is often overlooked through the turning upside - down of the dissection. The rounded end of the heart is - uppermost, the pointed end of it is largely fleshy and - thick, and in its cavities there are tendons. In other - animals which have a chest the heart lies in the middle - of the chest; in men, more to the left side, between the - nipples, a little inclined to the left nipple in the - upper part of the chest. The heart is not large, and its - general form is not elongated but rounded, except that - the apex is produced into a point. - - (_B_) “It has, as already stated, three cavities, the - largest of them is on the right, the smallest on the - left, the middle-sized one in the middle; they have all, - also the two small ones, passages (τετρημένας) towards - the lung, very evidently as respects one of the cavities. - In the region of the union [with the great vein and the - aorta] the largest cavity is connected with the largest - vein (near which is the mesentery); the middle cavity - with the aorta. - - (_C_) “Canals (πόροι) from the heart pass to the lung and - divide in the same fashion as the windpipe does, closely - accompanying those from the windpipe through the whole - lung. The canals from the heart are uppermost. - - (_D_) “No canal is common [to the branches of the - windpipe and those of the vein] (οὐδεὶς δ’ ἐστὶ κοινὸς - πόρος) but through those parts of them which are in - contact (τὴν σύναψιν) the air passes in and they [the - πόροι] carry it to the heart. - - (_E_) “One of the canals leads to the right cavity, the - other to the left. - - (_F_) “Of all the viscera, the heart alone contains blood - [in itself]. The lung contains blood, not in itself but - in the veins, the heart in itself; for in each of the - cavities there is blood; the thinnest is in the middle - cavity.” - - Book iii. 3.—(_G_) “Two veins lie in the thorax alongside - the spine, on its inner face; the larger more forwards, - the smaller behind; the larger more to the right, the - smaller, which some call _aorta_ (on account of the - tendinous part of it seen in dead bodies), to the left. - These take their origin from the heart; they pass entire, - preserving the nature of veins, through the other viscera - that they reach; while the heart is rather a part of - them, and more especially of the anterior and larger one, - which is continued into veins above and below, while - between these is the heart. - - (_H_) “All hearts contain cavities, but, in those of very - small animals, the largest [cavity] is hardly visible, - those of middling size have another, and the biggest all - three. - - (_I_) “The point of the heart is directed forwards, as - was mentioned at first; the largest cavity to the right - and upper side of it, the smallest to the left, and the - middle-sized one between these; both of these are much - smaller than the largest. - - (_K_) “They are all connected by passages (συντέτρηνται) - with the lung, but, on account of the smallness of the - canals, this is obscure except in one. - - (_L_) “The great vein proceeds from the largest cavity - which lies upwards and to the right; next through the - hollow middle part (διὰ τοῦ κοίλου τοῦ μέσου) it becomes - vein again, this cavity being a part of the vein in which - the blood stagnates. - - (_M_) “The aorta [proceeds from] the middle [cavity], but - not in the same way, for it is connected [with the middle - cavity] by a much more narrow tube (σύριγγα). - - (_N_) “The [great] vein extends through the heart, - towards the aorta from the heart. - - (_O_) “The great vein is membranous like skin, the aorta - narrower than it and very tendinous, and as it extends - towards the head and the lower parts it becomes narrow - and altogether tendinous. - - (_P_) “In the first place, a part of the great vein - extends upwards from the heart towards the lung and - the attachment of the aorta, the vein being large and - undivided. It divides into two parts, the one to the - lung, the other to the spine and the lowest vertebra of - the neck. - - (_Q_) “The vein which extends to the lung first divides - into two parts for the two halves of it and then extends - alongside each tube (σύριγγα) and each passage (τρῆμα), - the larger beside the larger and the smaller beside the - smaller, so that no part [of the lung] can be found - from which a passage (τρῆμα) and a vein are absent. - The terminations are invisible on account of their - minuteness, but the whole lung appears full of blood. The - canals from the vein lie above the tubes given off from - the windpipe.” - -The key to the whole of the foregoing description of the heart lies -in the passages (_G_) and (_L_). They prove that Aristotle, like -Galen, five hundred years afterwards, and like the great majority -of the old Greek anatomists, did not reckon what we call the right -auricle as a constituent of the heart at all, but as a hollow part, or -dilatation, of the “great vein.” Aristotle is careful to state that his -observations were conducted on suffocated animals; and if any one will -lay open the thorax of a dog or a rabbit, which has been killed with -chloroform, in such a manner as to avoid wounding any important vessel, -he will at once see why Aristotle adopted this view. - -For, as the subjoined figure (p. 185) shows, the vena cava inferior -(_b_), the right auricle (_R.a._), and the vena cava superior and -innominate vein (_V.I._) distended with blood seem to form one -continuous column, to which the heart is attached as a sort of -appendage. This column is, as Aristotle says, vein above (_a_) and vein -below (_b_), the upper and the lower divisions being connected διὰ -τοῦ κοίλου τοῦ μέσου—or by means of the intervening cavity or chamber -(_R.a._)—which is that which we call the right auricle. - -[Illustration: - - A dog having been killed by chloroform, enough of the - right wall of the thorax was removed, without any notable - bleeding, to expose the thoracic viscera. A carefully - measured outline sketch of the parts _in situ_ was then - made, and on dissection, twenty-four hours afterwards, - the necessary anatomical details were added. The woodcut - is a faithfully reduced copy of the drawing thus - constructed; and it represents the relations of the heart - and great vessels as Aristotle saw them in a suffocated - animal. - - All but the inner lobe of the right lung has been - removed; as well as the right half of the pericardium and - the right walls of the right auricle and ventricle. It - must be remembered that the thin transparent pericardial - membrane appears nothing like so distinct in nature. - - _a.b._, Aristotle’s “great vein”; _V.I._, right vena - innominata and vena cava superior; _b_, the inferior - vena cava; _R.a._, the “hollow middle” part of the great - vein or the right auricle; _R.v′_, the prolongation of - the cavity of the right ventricle _R.v_ towards the - pulmonary artery; _tr_, one of the tricuspid valves; - _Pc_, the pericardium; _I.sv_, superior intercostal - vein; _Az_, vena azygos; _P.A._, right pulmonary artery; - _Br_, right bronchus; _L_, inner lobe of the right lung; - _Œ_, œsophagus; _Ao_, descending aorta; _H_, liver, in - section, with hepatic vein, vena portæ, and gall-bladder, - _gb_, separated by the diaphragm, also seen in section, - from the thoracic cavity.] - -But when, from the four cavities of the heart recognised by us moderns, -one is excluded, there remain three—which is just what Aristotle says. -The solution of the difficulty is, in fact, as absurdly simple as that -presented by the egg of Columbus; and any error there may be, is not -to be put down to Aristotle, but to that inability to comprehend that -the same fact may be accurately described in different ways, which -is the special characteristic of the commentatorial mind. That the -three cavities mentioned by Aristotle are just those which remain if -the right auricle is omitted, is plain enough from what is said in -(_B_), (_C_), (_E_), (_I_), and (_L_). For, in a suffocated animal, -the “right cavity” which is directly connected with the great vein, -and is obviously the right ventricle, being distended with blood, will -look much larger than the middle cavity, which, since it gives rise -to the aorta, can only be the left ventricle. And this, again, will -appear larger than the thin and collapsed left auricle, which must -be Aristotle’s left cavity, inasmuch as this cavity is said to be -connected by πόροι with the lung. The reason why Aristotle considered -the left auricle to be a part of the heart, while he merged the right -auricle in the great vein, is, obviously, the small relative size of -the venous trunks and their sharper demarcation from the auricle. -Galen, however, perhaps more consistently, regarded the left auricle -also as a mere part of the “arteria venosa.” The canal which leads -from the right cavity of the heart to the lung (or, as Aristotle -puts it (_E_), from the lung to the heart) is, without doubt, the -pulmonary artery. But it may be said that, in this case, Aristotle -contradicts himself, inasmuch as in (_P_) and (_Q_) a vessel, which -is obviously the pulmonary artery, is described as a branch of the -great vein. However, this difficulty also disappears, if we reflect -that, in Aristotle’s way of looking at the matter, the line of -demarcation between the great vein and the heart coincides with the -right auriculo-ventricular aperture; and that, inasmuch as the conical -prolongation of the right ventricle which leads to the pulmonary -artery (_R.v′_ in the Figure), lies close in front of the auricle, -its base may very easily (as the figure shows) be regarded as part of -the general opening of the great vein into the right ventricle. In -fact, it is clear that Aristotle, having failed to notice the valves -of the heart, did not distinguish the part of the right ventricle -from which the pulmonary artery arises (_R.v′_) from the proper trunk -of the artery on the one hand, and from the right auricle (_R.a_) on -the other. Thus the root, as we may call it, of the pulmonary artery -and the right auricle, taken together, are spoken of as the “part of -the great vein which extends upwards” (_P_); and, as the vena azygos -(_Az_) was one branch of this, so the “vein to the lung” was regarded -as another branch of it. But the latter branch, being given off close -to the connection of the great vein with the ventricle, was also -counted as one of the two πόροι by which the “heart” (that is to say -the right ventricle, the left ventricle, and the left auricle of our -nomenclature) communicates with the lung. - -The only other difficulty that I observe is connected with (_K_). If -Aristotle intended by this to affirm that the middle cavity (the left -ventricle), like the other two, is directly connected with the lung by -a πόρος, he would be in error. But he has excluded this interpretation -of his words by (_E_), in which the number and relations of the -canals, the existence of which he admits, are distinctly defined. I -can only imagine then, that, so far as this passage applies to the -left ventricle, it merely refers to the indirect communication of that -cavity with the vessels of the lungs, through the left auricle. - -On this evidence I submit that there is no escape from the conclusion -that, instead of having committed a gross blunder, Aristotle has given -a description of the heart which, so far as it goes, is remarkably -accurate. He is in error only in regard to the differences which he -imagines to exist between large and small hearts (_H_). - -Cuvier (who has been followed by other commentators) ascribes another -error to Aristotle:— - - “Aristote suppose que la trachée-artère se prolonge - jusqu’au cœur, et semble croire, en conséquence, que - l’air y pénétre (_l. c._ p. 152).” - -Upon what foundation Cuvier rested the first of these two assertions, -I am at a loss to divine. As a matter of fact, it will appear from the -following excerpts that Aristotle gives an account of the structure of -the lungs which is almost as good as that of the heart, and that it -contains nothing about any prolongation of the windpipe to the heart. - - “Within the neck lie what is called the œsophagus (so - named on account of its length and its narrowness) and - the windpipe (ἀρτηρία). The position of the windpipe in - all animals that have one, is in front of the œsophagus. - All animals which possess a lung have a windpipe. The - windpipe is of a cartilaginous nature and is exsanguine, - but is surrounded by many little veins.... - - “It goes downwards towards the middle of the lung, and - then divides for each of the halves of the lung. In all - animals that possess one, the lung is divided into two - parts; but, in those which bring forth their young alive, - the separation is not equally well marked, least of all - in man. - - “In oviparous animals, such as birds, and in quadrupeds - which are oviparous, the one half of the lung is widely - separated from the other; so that it appears as if they - had two lungs. And from being single, the windpipe - becomes (divided into) two, which extend to each half of - the lung. It is fastened to the great vein, and to what - is called the aorta. When the windpipe is blown up, the - air passes into the hollow parts of the lung. In these, - are cartilaginous tubes (διαφύσεις) which unite at an - angle; from the tubes passages (τρήματα) traverse the - whole of the lung; they are continually given off, the - smaller from the larger.” (Book i. 16.) - -That Aristotle should speak of the lung as a single organ divided into -two halves, and should say that the division is least marked in man, -is puzzling at first; but the statement becomes intelligible, if we -reflect upon the close union of the bronchi, the pulmonary vessels and -the mediastinal walls of the pleuræ, in mammals;[38] and it is quite -true that the lungs are much more obviously distinct from one another -in birds. - -Aubert and Wimmer translate the last paragraph of the passage just -cited as follows:— - - “Diese haben aber knorpelige Scheidewände, welche unter - spitzen Winkeln zusammentreten, und aus ihnen führen - Oeffnungen durch die ganze Lunge, indem sie sich in immer - kleineren verzweigen.” - -But I cannot think that by διαφύσεις and τρήματα, in this passage, -Aristotle meant either “partitions” or openings in the ordinary -sense of the latter word. For, in Book iii. Cap. 3, in describing -the distribution of the “vein which goes to the lung” (the pulmonary -artery), he says that it - - “extends alongside each tube (σύριγγα) and each passage - (τρῆμα), the larger beside the larger, and the smaller - beside the smaller; so that no part (of the lung) can be - found from which a passage (τρῆμα) and a vein are absent.” - -Moreover, in Book i. 17, he says— - - “Canals (πόροι) from the heart pass to the lung and - divide in the same fashion as the windpipe does, closely - accompanying those from the windpipe through the whole - lung.” - -And again in Book i. 17— - - “It (the lung) is entirely spongy, and alongside of each - tube (σύριγγα) run canals (πόροι) from the great vein.” - -On comparing the last three statements with the facts of the case, it -is plain that by σύριγγες, or tubes, Aristotle means the bronchi and so -many of their larger divisions as obviously contain cartilages; and -that by διαφύσεις χονδρώδεις he denotes the same things; and, if this -be so, then the τρήματα must be the smaller bronchial canals, in which -the cartilages disappear. - -This view of the structure of the lung is perfectly correct so far -as it extends; and, bearing it in mind, we shall be in a position to -understand what Aristotle thought about the passage of air from the -lungs into the heart. In every part of the lung, he says, in effect, -there is an air tube which is derived from the trachea, and other tubes -which are derived from the πόροι which connect the lung with the heart -(_suprà_, _C_). Their applied walls constitute the thin “synapses” (τὴν -σύναψιν) through which the air passes out of the air tubes into the -πόροι, or blood-vessels, by transudation or diffusion; for there is no -community between the cavities of the air tubes and cavities of the -canals; that is to say, no opening from one into the other (_suprà_, -_D_). - -On the words “κοινὸς πόρος” Aubert and Wimmer remark (_l. c._ p. 239), -“Da A. die Ansicht hat die Lungenluft würde dem Herzen zugeführt, -so postulirt er statt vieler kleiner Verbindungen einen grossen -Verbindungsgang zwischen Lunge und Herz.” - -But does Aristotle make this assumption? The only evidence so far as -I know in favour of the affirmative answer to this question is the -following passage:— - - “Συνήρτεται δὲ καὶ ἡ καρδία τῇ ἀρτηριᾷ πιμελώδεσι - καὶ χονδρώδεσι καὶ ἰνώδεσι δεσμοῖς· ᾗ δὲ συνήρτεται, - κοῖλόν ἐστιν. φυσωμένης δὲ τῆς ἀρτηρίας μὲν ἐνίοις ἐν οὐ - κατάδηλον ποιεῖ, ἐν δὲ τοῖς μείζοσι τῶν ζῴων δῆλον ὅτι - εἰσέρχεται τὸ πνεῦμα εἰς αὐτὴν” (i. cap. 16). - - “The heart and the windpipe are connected by fatty and - cartilaginous and fibrous bands; where they are connected - it is hollow. Blowing into the windpipe does not show - clearly in some animals, but in the larger animals it is - clear that the air goes into it.” - -Aubert and Wimmer give a somewhat different rendering of this passage:— - - “Auch das Herz hängt mit der Luftröhre durch fettreiche, - knorpelige und faserige Bänder zusammen; und da, wo sie - zusammenhängen, ist eine Höhlung. Beim Aufblasen der - Lunge wird es bei manchen Thieren nicht wahrnehmbar, bei - den grösseren aber ist es offenbar, dass die Luft in das - Herz gelangt.” - -The sense here turns upon the signification which is to be ascribed to -εἰς αὐτὴν. But if these words refer to the heart, then Aristotle has -distinctly pointed out the road which the air, in his opinion, takes, -namely, through the “synapses” (_D_); and there is no reason that I -can discover to believe that he “postulated” any other and more direct -communication. - -With respect to the meaning of κοῖλόν ἐστιν, Aubert and Wimmer observe:— - - “Dies scheint wohl die kurze Lungenvene zu sein. - Schneider bezieht dies auf die Vorkammern, allein diese - werden unten als Höhlen des Herzens beschrieben.” - -I am disposed to think, on the contrary, that the words refer simply -to the cavity of the pericardium. For a part of this cavity (_sinus -transversus pericardii_) lies between the aorta, on the one hand, and -the pulmonary vessels with the bifurcation of the trachea, on the other -hand, and is much more conspicuous in some animals than in man. It is -strictly correct, therefore, in Aristotle’s words, to say that where -the heart and the windpipe are connected “it is hollow.” If he had -meant to speak of one of the pulmonary veins, or of any of the cavities -of the heart, he would have used the terms πόροι or κοιλίας which he -always employs for these parts. - -According to Aristotle, then, the air taken into the lungs passes, from -the final ramifications of the bronchial tubes into the corresponding -branches of the pulmonary blood-vessels, not through openings, but by -transudation, or, as we should nowadays say, diffusion, through the -thin partitions formed by the applied coats of the two sets of canals. -But the “pneuma” which thus reached the interior of the blood-vessels -was not, in Aristotle’s opinion, exactly the same thing as the air. -It was “ἀὴρ πολὺς ῥέων καὶ ἀθρόος” (“De Mundo,” iv. 9)—subtilised and -condensed air; and it is hard to make out whether Aristotle considered -it to possess the physical properties of an elastic fluid or those of -a liquid. As he affirms that all the cavities of the heart contain -blood (_F_), it is clear that he did not hold the erroneous view -propounded in the next generation by Erasistratus. On the other hand, -the fact that he supposes that the spermatic arteries do not contain -blood but only an αἱματῶδης ὑγρόν (“Hist. Animalium,” iii. 1), shows -that his notions respecting the contents of the arteries were vague. -Nor does he seem to have known that the pulse is characteristic only -of the arteries; and as he thought that the arteries end in solid -fibrous bands, he naturally could not have entertained the faintest -conception of the true motion of the blood. But, without attempting -to read into Aristotle modern conceptions which never entered his -mind, it is only just to observe that his view of what becomes of the -air taken into the lungs is by no means worthy of contempt as a gross -error. On the contrary, here, as in the case of his anatomy of the -heart, what Aristotle asserts is true as far as it goes. Something -does actually pass from the air contained in the lungs through the -coats of the vessels into the blood, and thence to the heart; to wit, -oxygen. And I think that it speaks very well for ancient Greek science -that the investigator of so difficult a physiological problem as that -of respiration, should have arrived at a conclusion, the statement of -which, after the lapse of more than two thousand years, can be accepted -as a thoroughly established scientific truth. - -I trust that the case in favour of removing the statements about -the heart, from the list of the “errors of Aristotle” is now clear; -and that the evidence proves, on the contrary, that they justify -us in forming a very favourable estimate of the oldest anatomical -investigations among the Greeks of which any sufficient record remains. - -But is Aristotle to be credited with the merit of having ascertained so -much of the truth? This question will not appear superfluous to those -who are acquainted with the extraordinary history of Aristotle’s works, -or who adopt the conclusion of Aubert and Wimmer, that, of the ten -books of the “Historia Animalium” which have come down to us, three -are largely or entirely spurious, and that the others contain many -interpolations by later writers. - -It so happens, however, that, apart from other reasons, there are -satisfactory internal grounds for ascribing the account of the heart -to a writer of the time at which Aristotle lived. For, within thirty -years of his death, the anatomists of the Alexandrian school had -thoroughly investigated the structure and the functions of the valves -of the heart. During this time, the manuscripts of Aristotle were in -the possession of Theophrastus; and no interpolator of later date would -have shown that he was ignorant of the nature and significance of -these important structures, by the brief and obscure allusion—“in its -cavities there are tendons” (_A_). On the other hand, Polybus, whose -account of the vascular system is quoted in the “Historia Animalium” -was an elder contemporary of Aristotle. Hence, if any part of the -work faithfully represents that which Aristotle taught, we may safely -conclude that the description of the heart does so. Having granted -this much, however, it is another question, whether Aristotle is to -be regarded as the first discoverer of the facts which he has so well -stated, or whether he, like other men, was the intellectual child of -his time and simply carried on a step or two the work which had been -commenced by others. - -On the subject of Aristotle’s significance as an original worker in -biology extraordinarily divergent views have been put forward. If we -are to adopt Cuvier’s estimate, Aristotle was simply a miracle:— - - “Avant Aristote la philosophie, entièrement spéculative, - se perdait dans les abstractions dépourvues de fondement; - la science n’existait pas. Il semble qu’elle soit - sortie toute faite du cerveau d’Aristote comme Minerve, - toute armée, du cerveau de Jupiter. Seul, en effet, - sans antécédents, sans rien emprunter aux siècles qui - l’avaient précédé, puisqu’ils n’avaient rien produit de - solide, le disciple de Platon découvrit et démontra plus - de vérités, executa plus de travaux scientifiques en un - vie de soixante-deux ans, qu’après lui vingt siècles n’en - ont pu faire,”[39] etc. etc. - - “Aristote est le premier qui ait introduit la méthode - de l’induction, de la comparaison des observations - pour en faire sortir des idées générales, et celle de - l’expérience pour multiplier les faits dont ces idées - générales peuvent être déduites.”—ii. p. 515. - -The late Mr. G. H. Lewes,[40] on the contrary, tells us “on a -superficial examination, therefore, he [Aristotle] will seem to have -given tolerable descriptions; especially if approached with that -disposition to discover marvels which unconsciously determines us -in our study of eminent writers. But a more unbiassed and impartial -criticism will disclose that he has given no single anatomical -description of the least value. All that he knew may have been known, -and probably was known, without dissection.... I do not assert that -he never opened an animal; on the contrary it seems highly probable -that he had opened many.... He never followed the course of a vessel -or a nerve; never laid bare the origin and insertion of a muscle; -never discriminated the component parts of organs; never made clear to -himself the connection of organs into systems.”—(pp. 156-7.) - -In the face of the description of the heart and lungs, just quoted, -I think we may venture to say that no one who has acquired even an -elementary practical acquaintance with anatomy, and knows of his own -knowledge that which Aristotle describes, will agree with the opinion -expressed by Mr. Lewes; and those who turn to the accounts of the -structure of the rock lobster and the common lobster, or to that of the -Cephalopods and other Mollusks, in the fourth book of the “Historia -Animalium” will probably feel inclined to object to it still more -strongly. - -On the other hand, Cuvier’s exaggerated panegyric will as little bear -the test of cool discussion. In Greece, the century before Aristotle’s -birth was a period of great intellectual activity, in the field of -physical science no less than elsewhere. The method of induction has -never been used to better effect than by Hippocrates; and the labours -of such men as Alkmeon, Demokritus, and Polybus, among Aristotle’s -predecessors; Diokles, and Praxagoras, among his contemporaries, laid a -solid foundation for the scientific study of anatomy and development, -independently of his labours. Aristotle himself informs us that the -dissection of animals was commonly practised; that the aorta had been -distinguished from the great vein; and that the connection of both with -the heart had been observed by his predecessors. What they thought -about the structure of the heart itself or that of the lungs, he does -not tell us, and we have no means of knowing. So far from arrogantly -suggesting that he owed nothing to his predecessors, Aristotle is -careful to refer to their observations, and to explain why, in his -judgment, they fell into the errors which he corrects. - -Aristotle’s knowledge, in fact, appears to have stood in the same -relation to that of such men as Polybus and Diogenes of Apollonia, as -that of Herophilus and Erasistratus did to his own, so far as the heart -is concerned. He carried science a step beyond the point at which he -found it; a meritorious, but not a miraculous, achievement. What he -did, required the possession of very good powers of observation; if -they had been powers of the highest class, he could hardly have left -such conspicuous objects as the valves of the heart to be discovered by -his successors. - -And this leads me to make a final remark upon a singular feature of -the “Historia Animalium.” As a whole, it is a most notable production, -full of accurate information, and of extremely acute generalisations of -the observations accumulated by naturalists up to that time. And yet, -every here and there, one stumbles upon assertions respecting matters -which lie within the scope of the commonest inspection, which are not -so much to be called errors, as stupidities. What is to be made of the -statement that the sutures of women’s skulls are different from those -of men; that men and sundry male animals have more teeth than their -respective females; that the back of the skull is empty; and so on? It -is simply incredible to me, that the Aristotle who wrote the account of -the heart, also committed himself to absurdities which can be excused -by no theoretical prepossession and which are contradicted by the -plainest observation. - -What, after all, were the original manuscripts of the “Historia -Animalium”? If they were notes of Aristotle’s lectures taken by some of -his students, any lecturer who has chanced to look through such notes, -would find the interspersion of a foundation of general and sometimes -minute accuracy, with patches of transcendent blundering, perfectly -intelligible. Some competent Greek scholar may perhaps think it worth -while to tell us what may be said for or against the hypothesis thus -hinted. One obvious difficulty in the way of adopting it is the fact -that, in other works, Aristotle refers to the “Historia Animalium” as -if it had already been made public by himself. - - - - -IX. - -ON THE HYPOTHESIS THAT ANIMALS ARE AUTOMATA, AND ITS HISTORY. - - -The first half of the seventeenth century is one of the great epochs -of biological science. For though suggestions and indications of the -conceptions which took definite shape, at that time, are to be met -with in works of earlier date, they are little more than the shadows -which coming truth casts forward; men’s knowledge was neither extensive -enough, nor exact enough, to show them the solid body of fact which -threw these shadows. - -But, in the seventeenth century, the idea that the physical processes -of life are capable of being explained in the same way as other -physical phenomena, and, therefore, that the living body is a -mechanism, was proved to be true for certain classes of vital actions; -and, having thus taken firm root in irrefragable fact, this conception -has not only successfully repelled every assault which has been made -upon it, but has steadily grown in force and extent of application, -until it is now the expressed or implied fundamental proposition of the -whole doctrine of scientific Physiology. - -If we ask to whom mankind are indebted for this great service, the -general voice will name William Harvey. For, by his discovery of the -circulation of the blood in the higher animals, by his explanation of -the nature of the mechanism by which that circulation is effected, -and by his no less remarkable, though less known, investigations of -the process of development, Harvey solidly laid the foundations of -all those physical explanations of the functions of sustentation and -reproduction which modern physiologists have achieved. - -But the living body is not only sustained and reproduced: it adjusts -itself to external and internal changes; it moves and feels. The -attempt to reduce the endless complexities of animal motion and -feeling to law and order is, at least, as important a part of the task -of the physiologist as the elucidation of what are sometimes called -the vegetative processes. Harvey did not make this attempt himself; -but the influence of his work upon the man who did make it is patent -and unquestionable. This man was René Descartes, who, though by many -years Harvey’s junior, died before him; and yet, in his short span -of fifty-four years, took an undisputed place, not only among the -chiefs of philosophy, but amongst the greatest and most original of -mathematicians; while, in my belief, he is no less certainly entitled -to the rank of a great and original physiologist; inasmuch as he did -for the physiology of motion and sensation that which Harvey had done -for the circulation of the blood, and opened up that road to the -mechanical theory of these processes, which has been followed by all -his successors. - -Descartes was no mere speculator, as some would have us believe: but a -man who knew of his own knowledge what was to be known of the facts of -anatomy and physiology in his day. He was an unwearied dissector and -observer; and it is said, that, on a visitor once asking to see his -library, Descartes led him into a room set aside for dissections, and -full of specimens under examination. “There,” said he, “is my library.” - -I anticipate a smile of incredulity when I thus champion Descartes’ -claim to be considered a physiologist of the first rank. I expect to -be told that I have read into his works what I find there, and to be -asked, Why is it that we are left to discover Descartes’ deserts at -this time of day, more than two centuries after his death? How is it -that Descartes is utterly ignored in some of the latest works which -treat expressly of the subject in which he is said to have been so -great? - -It is much easier to ask such questions than to answer them, especially -if one desires to be on good terms with one’s contemporaries; but, if I -must give an answer, it is this: The growth of physical science is now -so prodigiously rapid, that those who are actively engaged in keeping -up with the present, have much ado to find time to look at the past, -and even grow into the habit of neglecting it. But, natural as this -result may be, it is none the less detrimental. The intellect loses, -for there is assuredly no more effectual method of clearing up one’s -own mind on any subject than by talking it over, so to speak, with -men of real power and grasp, who have considered it from a totally -different point of view. The parallax of time helps us to the true -position of a conception, as the parallax of space helps us to that of -a star. And the moral nature loses no less. It is well to turn aside -from the fretful stir of the present and to dwell with gratitude and -respect upon the services of those “mighty men of old who have gone -down to the grave with their weapons of war,” but who, while they yet -lived, won splendid victories over ignorance. It is well, again, to -reflect that the fame of Descartes filled all Europe, and his authority -overshadowed it, for a century; while now, most of those who know his -name think of him, either as a person who had some preposterous notions -about vortices and was deservedly annihilated by the great Sir Isaac -Newton; or as the apostle of an essentially vicious method of deductive -speculation; and that, nevertheless, neither the chatter of shifting -opinion, nor the silence of personal oblivion, has in the slightest -degree affected the growth of the great ideas of which he was the -instrument and the mouthpiece. - -It is a matter of fact that the greatest physiologist of the eighteenth -century, Haller, in treating of the functions of nerve, does little -more than reproduce and enlarge upon the ideas of Descartes. It is a -matter of fact that David Hartley, in his remarkable work the “Essay -on Man,” expressly, though still insufficiently, acknowledges the -resemblance of his fundamental conceptions to those of Descartes; and -I shall now endeavour to show that a series of propositions, which -constitute the foundation and essence of the modern physiology of the -nervous system, are fully expressed and illustrated in the works of -Descartes. - - I. _The brain is the organ of sensation, thought, and - emotion; that is to say, some change in the condition of - the matter of this organ is the invariable antecedent of - the state of consciousness to which each of these terms - is applied._ - -In the “Principes de la Philosophie” (§ 169), Descartes says:—[41] - - “Although the soul is united to the whole body, its - principal functions are, nevertheless, performed in - the brain; it is here that it not only understands and - imagines, but also feels; and this is effected by the - intermediation of the nerves, which extend in the form - of delicate threads from the brain to all parts of the - body, to which they are attached in such a manner, that - we can hardly touch any part of the body without setting - the extremity of some nerve in motion. This motion passes - along the nerve to that part of the brain which is the - common sensorium, as I have sufficiently explained in - my Treatise on Dioptrics; and the movements which thus - travel along the nerves, as far as that part of the - brain with which the soul is closely joined and united, - cause it, by reason of their diverse characters, to have - different thoughts. And it is these different thoughts of - the soul, which arise immediately from the movements that - are excited by the nerves in the brain, which we properly - term our feelings, or the perceptions of our senses.” - -Elsewhere,[42] Descartes, in arguing that the seat of the passions is -not (as many suppose) the heart, but the brain, uses the following -remarkable language:— - - “The opinion of those who think that the soul receives - its passions in the heart, is of no weight, for it is - based upon the fact that the passions cause a change to - be felt in that organ; and it is easy to see that this - change is felt, as if it were in the heart, only by the - intermediation of a little nerve which descends from the - brain to it; Just as pain is felt, as if it were in the - foot, by the intermediation of the nerves of the foot; - and the stars are perceived, as if they were in the - heavens, by the intermediation of their light and of the - optic nerves. So that it is no more necessary for the - soul to exert its functions immediately in the heart, to - feel its passions there, than it is necessary that it - should be in the heavens to see the stars there.” - -This definite allocation of all the phenomena of consciousness to the -brain as their organ, was a step the value of which it is difficult -for us to appraise, so completely has Descartes’ view incorporated -itself with every-day thought and common language. A lunatic is said -to be “crack-brained” or “touched in the head,” a confused thinker -is “muddle-headed,” while a clever man is said to have “plenty of -brains;” but it must be remembered that at the end of the last century -a considerable, though much over-estimated, anatomist, Bichat, so far -from having reached the level of Descartes, could gravely argue that -the apparatuses of organic life are the sole seat of the passions, -which in no way affect the brain, except so far as it is the agent by -which the influence of the passions is transmitted to the muscles.[43] - -Modern physiology, aided by pathology, easily demonstrates that the -brain is the seat of all forms of consciousness, and fully bears out -Descartes’ explanation of the reference of those sensations in the -viscera which accompany intense emotion, to these organs. It proves, -directly, that those states of consciousness which we call sensations -are the immediate consequent of a change in the brain excited by -the sensory nerves; and, on the well-known effects of injuries, of -stimulants, and of narcotics, it bases the conclusion that thought and -emotion are, in like manner, the consequents of physical antecedents. - - II. _The movements of animals are due to the change of - form of muscles, which shorten and become thicker; and - this change of form in a muscle arises from a motion of - the substance contained within the nerves which go to the - muscle_. - -In the “Passions de l’Âme,” Art. vii., Descartes writes:— - - “Moreover, we know that all the movements of the limbs - depend on the muscles, and that these muscles are opposed - to one another in such a manner, that when one of them - shortens, it draws along the part of the body to which - it is attached, and so gives rise to a simultaneous - elongation of the muscle which is opposed to it. Then, - if it happens, afterwards, that the latter shortens, it - causes the former to elongate, and draws towards itself - the part to which it is attached. Lastly, we know that - all these movements of the muscles, as all the senses, - depend on the nerves, which are like little threads or - tubes, which all come from the brain, and, like it, - contain a certain very subtle air or wind, termed the - animal spirits.” - -The property of muscle mentioned by Descartes now goes by the general -name of contractility, but his definition of it remains untouched. The -long-continued controversy whether contractile substance, speaking -generally, has an inherent power of contraction, or whether it -contracts only in virtue of an influence exerted by nerve, is now -settled in Haller’s favour; but Descartes’ statement of the dependence -of muscular contraction on nerve holds good for the higher forms of -muscle, under normal circumstances; so that, although the structure of -the various modifications of contractile matter has been worked out -with astonishing minuteness—although the delicate physical and chemical -changes which accompany muscular contraction have been determined to -an extent of which Descartes could not have dreamed, and have quite -upset his hypothesis that the cause of the shortening and thickening of -the muscle is the flow of animal spirits into it from the nerves—the -important and fundamental part of his statement remains perfectly true. - -The like may be affirmed of what he says about nerve. We know now that -nerves are not exactly tubes, and that “animal spirits” are myths; but -the exquisitely refined methods of investigation of Dubois-Reymond and -of Helmholz have no less clearly proved that the antecedent of ordinary -muscular contraction is a motion of the molecules of the nerve going to -the muscle; and that this motion is propagated with a measurable, and -by no means great, velocity, through the substance of the nerve towards -the muscle. - -With the progress of research, the term “animal spirits” gave way to -“nervous fluid,” and “nervous fluid” has now given way to “molecular -motion of nerve-substance.” Our conceptions of what takes place in -nerve have altered in the same way as our conceptions of what takes -place in a conducting wire have altered, since electricity was shown to -be not a fluid, but a mode of molecular motion. The change is of vast -importance, but it does not affect Descartes’ fundamental idea, that a -change in the substance of a motor nerve propagated towards a muscle is -the ordinary cause of muscular contraction. - - III. _The sensations of animals are due to a motion of - the substance of the nerves which connect the sensory - organs with the brain._ - -In _La Dioptrique_ (Discours Quatrième), Descartes explains, more fully -than in the passage cited above, his hypothesis of the mode of action -of sensory nerves:— - - “It is the little threads of which the inner substance - of the nerves is composed which subserve sensation. You - must conceive that these little threads, being inclosed - in tubes, which are always distended and kept open by - the animal spirits which they contain, neither press - upon nor interfere with one another, and are extended - from the brain to the extremities of all the members - which are sensitive—in such a manner, that the slightest - touch which excites the part of one of the members to - which a thread is attached, gives rise to a motion of - the part of the brain whence it arises, just as by - pulling one of the ends of a stretched cord, the other - end is instantaneously moved.... And we must take care - not to imagine that, in order to feel, the soul needs - to behold certain images sent by the objects of sense - to the brain, as our philosophers commonly suppose; - or, at least, we must conceive these images to be - something quite different from what they suppose them - to be. For, as all they suppose is that these images - ought to resemble the objects which they represent, it - is impossible for them to show how they can be formed by - the objects received by the organs of the external senses - and transmitted to the brain. And they have had no reason - for supposing the existence of these images except this; - seeing that the mind is readily excited by a picture to - conceive the object which is depicted, they have thought - that it must be excited in the same way to conceive those - objects which affect our senses by little pictures of - them formed in the head; instead of which we ought to - recollect that there are many things besides images which - may excite the mind, as, for example, signs and words, - which have not the least resemblance to the objects which - they signify.”[44] - -Modern physiology amends Descartes’ conception of the mode of action of -sensory nerves in detail, by showing that their structure is the same -as that of motor nerves; and that the changes which take place in them, -when the sensory organs with which they are connected are excited, are -of just the same nature as those which occur in motor nerves, when the -muscles to which they are distributed are made to contract: there is a -molecular change which, in the case of the sensory nerve, is propagated -towards the brain. But the great fact insisted upon by Descartes, that -no likeness of external things is, or can be, transmitted to the mind -by the sensory organs; on the contrary, that, between the external -cause of a sensation and the sensation, there is interposed a mode -of motion of nervous matter, of which the state of consciousness is -no likeness, but a mere symbol, is of the profoundest importance. It -is the physiological foundation of the doctrine of the relativity -of knowledge, and a more or less complete idealism is a necessary -consequence of it. - -For of two alternatives one must be true. Either consciousness is -the function of a something distinct from the brain, which we call -the soul, and a sensation is the mode in which this soul is affected -by the motion of a part of the brain; or there is no soul, and a -sensation is something generated by the mode of motion of a part of -the brain. In the former case, the phenomena of the senses are purely -spiritual affections; in the latter, they are something manufactured -by the mechanism of the body, and as unlike the causes which set that -mechanism in motion, as the sound of a repeater is unlike the pushing -of the spring which gives rise to it. - -The nervous system stands between consciousness and the assumed -external world, as an interpreter who can talk with his fingers stands -between a hidden speaker and a man who is stone deaf—and Realism is -equivalent to a belief on the part of the deaf man, that the speaker -must also be talking with his fingers. “Les extrêmes se touchent;” the -shibboleth of materialists that “thought is a secretion of the brain,” -is the Fichtean doctrine that “the phenomenal universe is the creation -of the Ego,” expressed in other language. - - IV. _The motion of the matter of a sensory nerve may - be transmitted through the brain to motor nerves, and - thereby give rise to contraction of the muscles to which - these motor nerves are distributed; and this reflection - of motion from a sensory into a motor nerve may take - place without volition, or even contrary to it._ - -In stating these important truths, Descartes defined that which we now -term “reflex action.” Indeed he almost uses the term itself, as he -talks of the “animal spirits” as “réfléchis,”[45] from the sensory into -the motor nerves. And that this use of the word “reflected” was no mere -accident, but that the importance and appropriateness of the idea it -suggests was fully understood by Descartes’ contemporaries, is apparent -from a passage in Willis’s well-known essay, “De Animâ Brutorum,” -published in 1672, in which, in giving an account of Descartes’ views, -he speaks of the animal spirits being diverted into motor channels, -“velut undulatione reflexâ.”[46] - -Nothing can be clearer in statement, or in illustration, than the view -of reflex action which Descartes gives in the “Passions de l’Âme,” Art. -xiii. - -After recapitulating the manner in which sensory impressions -transmitted by the sensory nerves to the brain give rise to sensation, -he proceeds:— - - “And in addition to the different feelings excited in the - soul by these different motions of the brain, the animal - spirits, without the intervention of the soul, may take - their course towards certain muscles, rather than towards - others, and thus move the limbs, as I shall prove by - an example. If some one moves his hand rapidly towards - our eyes, as if he were going to strike us, although - we know that he is a friend, that he does it only in - jest, and that he will be very careful to do us no harm, - nevertheless it will be hard to keep from winking. And - this shows, that it is not by the agency of the soul - that the eyes shut, since this action is contrary to - that volition which is the only, or at least the chief, - function of the soul; but it is because the mechanism - of our body is so disposed, that the motion of the hand - towards our eyes excites another movement in our brain, - and this sends the animal spirits into those muscles - which cause the eyelids to close.” - -Since Descartes’ time, experiment has eminently enlarged our knowledge -of the details of reflex action. The discovery of Bell has enabled us -to follow the tracks of the sensory and motor impulses, along distinct -bundles of nerve fibres; and the spinal cord, apart from the brain, has -been proved to be a great centre of reflex action; but the fundamental -conception remains as Descartes left it, and it is one of the pillars -of nerve physiology at the present day. - - V. _The motion of any given portion of the matter of the - brain excited by the motion of a sensory nerve, leaves - behind a readiness to be moved in the same way, in that - part. Anything which resuscitates the motion gives - rise to the appropriate feeling. This is the physical - mechanism of memory_. - -Descartes imagined that the pineal body (a curious appendage to the -upper side of the brain, the function of which, if it have any, is -wholly unknown) was the instrument through which the soul received -impressions from, and communicated them to, the brain. And he thus -endeavours to explain what happens when one tries to recollect -something:— - - “Thus when the soul wills to remember anything, this - volition, causing the [pineal] gland to incline itself - in different directions, drives the [animal] spirits - towards different regions of the brain, until they reach - that part in which are the traces, which the object - which it desires to remember has left. These traces are - produced thus: those pores of the brain through which the - [animal] spirits have previously been driven, by reason - of the presence of the object, have thereby acquired a - tendency to be opened by the animal spirits which return - towards them, more easily than other pores, so that the - animal spirits, impinging on these pores, enter them - more readily than others. By this means they excite a - particular movement in the pineal gland, which represents - the object to the soul, and causes it to know what it is - which it desired to recollect.”[47] - -That memory is dependent upon some condition of the brain is a fact -established by many considerations—among the most important of which -are the remarkable phenomena of aphasia. And that the condition of the -brain on which memory depends, is largely determined by the repeated -occurrence of that condition of its molecules, which gives rise to the -idea of the thing remembered, is no less certain. -Every boy who learns his lesson by repeating it exemplifies the fact. -Descartes, as we have seen, supposes that the pores of a given part -of the brain are stretched by the animal spirits, on the occurrence -of a sensation, and that the part of the brain thus stretched, being -imperfectly elastic, does not return to exactly its previous condition, -but remains more distensible than it was before. Hartley supposes -that the vibrations, excited by a sensory, or other, impression, -do not die away, but are represented by smaller vibrations or -“vibratiuncules,” the permanency and intensity of which are in relation -with the frequency of repetition of the primary vibrations. Haller has -substantially the same idea, but contents himself with the general term -“mutationes,” to express the cerebral change which is the cause of a -state of consciousness. These “mutationes” persist for a long time -after the cause which gives rise to them has ceased to operate, and -are arranged in the brain according to the order of coexistence and -succession of their causes. And he gives these persistent “mutationes” -the picturesque name of _vestigia rerum_, “quæ non in mente sed in ipso -corpore et in medulla quidem cerebri ineffabili modo incredibiliter -minutis notis et copia infinita, inscriptæ sunt.”[48] I do not know -that any modern theory of the physical conditions of memory differs -essentially from these, which are all children—_mutatis mutandis_—of -the Cartesian doctrine. Physiology is, at present, incompetent to -say anything positively about the matter, or to go farther than the -expression of the high probability, that every molecular change -which gives rise to a state of consciousness, leaves a more or less -persistent structural modification, through which the same molecular -change may be regenerated by other agencies than the cause which first -produced it. - -Thus far, the propositions respecting the physiology of the nervous -system which are stated by Descartes have simply been more clearly -defined, more fully illustrated, and, for the most part, demonstrated, -by modern physiological research. But there remains a doctrine to which -Descartes attached great weight, so that full acceptance of it became -a sort of note of a thorough-going Cartesian, but which, nevertheless, -is so opposed to ordinary prepossessions that it attained more general -notoriety, and gave rise to more discussion, than almost any other -Cartesian hypothesis. It is the doctrine, that brute animals are mere -machines or automata, devoid not only of reason, but of any kind of -consciousness, which is stated briefly in the “Discours de la Méthode,” -and more fully in the “Réponses aux Quatrièmes Objections,” and in the -correspondence with Henry More.[49] - -The process of reasoning by which Descartes arrived at this startling -conclusion is well shown in the following passage of the “Réponses:”— - - “But as regards the souls of beasts, although this is not - the place for considering them, and though, without a - general exposition of physics, I can say no more on this - subject than I have already said in the fifth part of my - Treatise on Method; yet, I will further state, here, that - it appears to me to be a very remarkable circumstance - that no movement can take place, either in the bodies of - beasts, or even in our own, if these bodies have not in - themselves all the organs and instruments by means of - which the very same movements would be accomplished in a - machine. So that, even in us, the spirit, or the soul, - does not directly move the limbs, but only determines - the course of that very subtle liquid which is called - the animal spirits, which, running continually from the - heart by the brain into the muscles, is the cause of all - the movements of our limbs, and often may cause many - different motions, one as easily as the other. - - “And it does not even always exert this determination; - for among the movements which take place in us, there - are many which do not depend on the mind at all, such - as the beating of the heart, the digestion of food, the - nutrition, the respiration, of those who sleep; and, - even in those who are awake, walking, singing, and other - similar actions, when they are performed without the - mind thinking about them. And, when one who falls from - a height throws his hands forwards to save his head, it - is in virtue of no ratiocination that he performs this - action; it does not depend upon his mind, but takes place - merely because his senses being affected by the present - danger, some change arises in his brain which determines - the animal spirits to pass thence into the nerves, in - such a manner as is required to produce this motion, - in the same way as in a machine, and without the mind - being able to hinder it. Now since we observe this in - ourselves, why should we be so much astonished if the - light reflected from the body of a wolf into the eye of - a sheep has the same force to excite in it the motion of - flight? - - “After having observed this, if we wish to learn by - reasoning, whether certain movements of beasts are - comparable to those which are effected in us by the - operation of the mind, or, on the contrary, to those - which depend only on the animal spirits and the - disposition of the organs, it is necessary to consider - the difference between the two, which I have explained - in the fifth part of the Discourse on Method (for I do - not think that any others are discoverable), and then - it will easily be seen, that all the actions of beasts - are similar only to those which we perform without the - help of our minds. For which reason we shall be forced - to conclude, that we know of the existence in them of no - other principle of motion than the disposition of their - organs and the continual affluence of animal spirits - produced by the heat of the heart, which attenuates and - subtilises the blood; and, at the same time, we shall - acknowledge that we have had no reason for assuming any - other principle, except that, not having distinguished - these two principles of motion, and seeing that the one, - which depends only on the animal spirits and the organs, - exists in beasts as well as in us, we have hastily - concluded that the other, which depends on mind and on - thought, was also possessed by them.” - -Descartes’ line of argument is perfectly clear. He starts from reflex -action in man, from the unquestionable fact that, in ourselves, -co-ordinate, purposive, actions may take place, without the -intervention of consciousness or volition, or even contrary to the -latter. As actions of a certain degree of complexity are brought about -by mere mechanism, why may not actions of still greater complexity -be the result of a more refined mechanism? What proof is there that -brutes are other than a superior race of marionettes, which eat without -pleasure, cry without pain, desire nothing, know nothing, and only -simulate intelligence as a bee simulates a mathematician?[50] - -The Port Royalists adopted the hypothesis that brutes are machines, -and are said to have carried its practical applications so far, as to -treat domestic animals with neglect, if not with actual cruelty. As -late as the middle of the eighteenth century, the problem was discussed -very fully and ably by Bouillier, in his “Essai philosophique sur l’Âme -des Bêtes,” while Condillac deals with it in his “Traité des Animaux;” -but since then it has received little attention. Nevertheless, modern -research has brought to light a great multitude of facts, which not -only show that Descartes’ view is defensible, but render it far more -defensible than it was in his day. - -It must be premised, that it is wholly impossible absolutely to prove -the presence or absence of consciousness in anything but one’s own -brain, though, by analogy, we are justified in assuming its existence -in other men. Now if, by some accident, a man’s spinal cord is divided, -his limbs are paralysed, so far as his volition is concerned, below -the point of injury; and he is incapable of experiencing all those -states of consciousness, which, in his uninjured state, would be -excited by irritation of those nerves which come off below the injury. -If the spinal cord is divided in the middle of the back, for example, -the skin of the feet may be cut, or pinched, or burned, or wetted -with vitriol, without any sensation of touch, or of pain, arising in -consciousness. So far as the man is concerned, therefore, the part of -the central nervous system which lies beyond the injury is cut off -from consciousness. It must indeed be admitted, that, if any one think -fit to maintain that the spinal cord below the injury is conscious, but -that it is cut off from any means of making its consciousness known to -the other consciousness in the brain, there is no means of driving him -from his position by logic. But assuredly there is no way of proving -it, and in the matter of consciousness, if in anything, we may hold by -the rule, “De non apparentibus et de non existentibus eadem est ratio.” -However near the brain the spinal cord is injured, consciousness -remains intact, except that the irritation of parts below the injury -is no longer represented by sensation. On the other hand, pressure -upon the anterior division of the brain, or extensive injuries to it, -abolish consciousness. Hence, it is a highly probable conclusion, -that consciousness in man depends upon the integrity of the anterior -division of the brain, while the middle and hinder divisions of the -brain, and the rest of the nervous centres, have nothing to do with it. -And it is further highly probable, that what is true for man is true -for other vertebrated animals. - -We may assume, then, that in a living vertebrated animal, any -segment of the cerebro-spinal axis (or spinal cord and brain) -separated from that anterior division of the brain which is the -organ of consciousness, is as completely incapable of giving rise to -consciousness, as we know it to be incapable of carrying out volitions. -Nevertheless, this separated segment of the spinal cord is not passive -and inert. On the contrary, it is the seat of extremely remarkable -powers. In our imaginary case of injury, the man would, as we have -seen, be devoid of sensation in his legs, and would have not the least -power of moving them. But, if the soles of his feet were tickled, the -legs would be drawn up, just as vigorously as they would have been -before the injury. We know exactly what happens when the soles of the -feet are tickled; a molecular change takes place in the sensory nerves -of the skin, and is propagated along them and through the posterior -roots of the spinal nerves, which are constituted by them, to the grey -matter of the spinal cord. Through that grey matter, the molecular -motion is reflected into the anterior roots of the same nerves, -constituted by the filaments which supply the muscles of the legs, and, -travelling along these motor filaments, reaches the muscles, which at -once contract, and cause the limbs to be drawn up. - -In order to move the legs in this way, a definite co-ordination of -muscular contractions is necessary; the muscles must contract in a -certain order and with duly proportioned force; and moreover, as the -feet are drawn away from the source of irritation, it may be said that -the action has a final cause, or is purposive. - -Thus it follows, that the grey matter of the segment of the man’s -spinal cord, though it is devoid of consciousness, nevertheless -responds to a simple stimulus by giving rise to a complex set of -muscular contractions, co-ordinated towards a definite end, and serving -an obvious purpose. - -If the spinal cord of a frog is cut across, so as to provide us with a -segment separated from the brain, we shall have a subject parallel to -the injured man, on which experiments can be made without remorse; as -we have a right to conclude that a frog’s spinal cord is not likely to -be conscious, when a man’s is not. - -Now the frog behaves just as the man did. The legs are utterly -paralysed, so far as voluntary movement is concerned; but they are -vigorously drawn up to the body when any irritant is applied to the -foot. But let us study our frog a little farther. Touch the skin of -the side of the body with a little acetic acid, which gives rise to -all the signs of great pain in an uninjured frog. In this case, there -can be no pain, because the application is made to a part of the skin -supplied with nerves which come off from the cord below the point of -section; nevertheless, the frog lifts up the limb of the same side, -and applies the foot to rub off the acetic acid; and, what is still -more remarkable, if the limb be held so that the frog cannot use it, it -will, by-and-by, move the limb of the other side, turn it across the -body, and use it for the same rubbing process. It is impossible that -the frog, if it were in its entirety and could reason, should perform -actions more purposive than these: and yet we have most complete -assurance that, in this case, the frog is not acting from purpose, has -no consciousness, and is a mere insensible machine. - -But now suppose that, instead of making a section of the cord in the -middle of the body, it had been made in such a manner as to separate -the hindermost division of the brain from the rest of the organ, and -suppose the foremost two-thirds of the brain entirely taken away. The -frog is then absolutely devoid of any spontaneity; it sits upright in -the attitude which a frog habitually assumes; and it will not stir -unless it is touched; but it differs from the frog which I have just -described in this, that, if it be thrown into the water, it begins to -swim, and swims just as well as the perfect frog does. But swimming -requires the combination and successive co-ordination of a great number -of muscular actions. And we are forced to conclude, that the impression -made upon the sensory nerves of the skin of the frog by the contact -with the water into which it is thrown, causes the transmission to the -central nervous apparatus of an impulse, which sets going a certain -machinery by which all the muscles of swimming are brought into play -in due co-ordination. If the frog be stimulated by some irritating -body, it jumps or walks as well as the complete frog can do. The simple -sensory impression, acting through the machinery of the cord, gives -rise to these complex combined movements. - -It is possible to go a step farther. Suppose that only the anterior -division of the brain—so much of it as lies in front of the “optic -lobes”—is removed. If that operation is performed quickly and -skilfully, the frog may be kept in a state of full bodily vigour for -months, or it may be for years; but it will sit unmoved. It sees -nothing; it hears nothing. It will starve sooner than feed itself, -although food put into its mouth is swallowed. On irritation, it jumps -or walks; if thrown into the water it swims. If it be put on the hand, -it sits there, crouched, perfectly quiet, and would sit there for ever. -If the hand be inclined very gently and slowly, so that the frog would -naturally tend to slip off, the creature’s fore paws are shifted on to -the edge of the hand, until he can just prevent himself from falling. -If the turning of the hand be slowly continued, he mounts up with great -care and deliberation, putting first one leg forward and then another, -until he balances himself with perfect precision upon the edge; and, if -the turning of the hand is continued, over he goes through the needful -set of muscular operations, until he comes to be seated in security, -upon the back of the hand. The doing of all this requires a delicacy of -co-ordination, and a precision of adjustment of the muscular apparatus -of the body, which are only comparable to those of a rope-dancer. To -the ordinary influences of light, the frog, deprived of its cerebral -hemispheres, appears to be blind. Nevertheless, if the animal be put -upon a table, with a book at some little distance between it and the -light, and the skin of the hinder part of its body is then irritated, -it will jump forward, avoiding the book by passing to the right or left -of it. Therefore, although the frog appears to have no sensation of -light, visible objects act through its brain upon the motor mechanism -of its body.[51] - -It is obvious, that had Descartes been acquainted with these remarkable -results of modern research, they would have furnished him with far -more powerful arguments than he possessed in favour of his view of -the automatism of brutes. The habits of a frog, leading its natural -life, involve such simple adaptations to surrounding conditions, -that the machinery which is competent to do so much without the -intervention of consciousness, might well do all. And this argument is -vastly strengthened by what has been learned in recent times of the -marvellously complex operations which are performed mechanically, and -to all appearance without consciousness, by men, when, in consequence -of injury or disease, they are reduced to a condition more or less -comparable to that of a frog, in which the anterior part of the brain -has been removed. A case has recently been published by an eminent -French physician, Dr. Mesnet, which illustrates this condition so -remarkably, that I make no apology for dwelling upon it at considerable -length.[52] - -A sergeant of the French army, F——, twenty-seven years of age, was -wounded during the battle of Bazeilles, by a ball which fractured his -left parietal bone. He ran his bayonet through the Prussian soldier who -wounded him, but almost immediately his right arm became paralysed; -after walking about two hundred yards, his right leg became similarly -affected, and he lost his senses. When he recovered them, three weeks -afterwards, in hospital at Mayence, the right half of the body was -completely paralysed, and remained in this condition for a year. At -present, the only trace of the paralysis which remains is a slight -weakness of the right half of the body. Three or four months after -the wound was inflicted, periodical disturbances of the functions of -the brain made their appearance, and have continued ever since. The -disturbances last from fifteen to thirty hours; the intervals at which -they occur being from fifteen to thirty days. - -For four years, therefore, the life of this man has been divided into -alternating phases—short abnormal states intervening between long -normal states. - -In the periods of normal life, the ex-sergeant’s health is perfect; he -is intelligent and kindly, and performs, satisfactorily, the duties of -a hospital attendant. The commencement of the abnormal state is ushered -in by uneasiness and a sense of weight about the forehead, which the -patient compares to the constriction of a circle of iron; and, after -its termination, he complains, for some hours, of dulness and heaviness -of the head. But the transition from the normal to the abnormal state -takes place in a few minutes, without convulsions or cries, and without -anything to indicate the change to a bystander. His movements remain -free and his expression calm, except for a contraction of the brow, an -incessant movement of the eyeballs, and a chewing motion of the jaws. -The eyes are wide open, and their pupils dilated. If the man happens to -be in a place to which he is accustomed, he walks about as usual; but, -if he is in a new place, or if obstacles are intentionally placed in -his way, he stumbles gently against them, stops, and then, feeling over -the objects with his hands, passes on one side of them. He offers no -resistance to any change of direction which may be impressed upon him, -or to the forcible acceleration or retardation of his movements. He -eats, drinks, smokes, walks about, dresses and undresses himself, rises -and goes to bed at the accustomed hours. Nevertheless, pins may be -run into his body, or strong electric shocks sent through it, without -causing the least indication of pain; no odorous substance, pleasant or -unpleasant, makes the least impression; he eats and drinks with avidity -whatever is offered, and takes asafœtida, or vinegar, or quinine, as -readily as water; no noise affects him; and light influences him only -under certain conditions. Dr. Mesnet remarks, that the sense of touch -alone seems to persist, and indeed to be more acute and delicate than -in the normal state; and it is by means of the nerves of touch, almost -exclusively, that his organism is brought into relation with the -external world. Here a difficulty arises. It is clear from the facts -detailed, that the nervous apparatus by which, in the normal state, -sensations of touch are excited, is that by which external influences -determine the movements of the body, in the abnormal state. But does -the state of consciousness, which we term a tactile sensation, -accompany the operation of this nervous apparatus in the abnormal -state? or is consciousness utterly absent, the man being reduced to an -insensible mechanism? - -It is impossible to obtain direct evidence in favour of the one -conclusion or the other; all that can be said is, that the case of the -frog shows that the man may be devoid of any kind of consciousness. - -A further difficult problem is this. The man is insensible to sensory -impressions made through the ear, the nose, the tongue, and, to a great -extent, the eye; nor is he susceptible of pain from causes operating -during his abnormal state. Nevertheless, it is possible so to act upon -his tactile apparatus, as to give rise to those molecular changes in -his sensorium, which are ordinarily the causes of associated trains of -ideas. I give a striking example of this process in Dr. Mesnet’s words:— - - “Il se promenait dans le jardin, sous un massif d’arbres, - on lui remet à la main sa canne qu’il avait laissé - tomber quelques minutes avant. Il la palpe, promène à - plusieurs reprises la main sur la poignée coudée de - sa canne—devient attentif—semble prêter l’oreille—et, - tout-à-coup, appelle ‘Henri!’ Puis, ‘Les voilà! Ils sont - au moins une vingtaine! à nous deux, nous en viendrons à - bout!’ Et alors portant la main derrière son dos comme - pour prendre une cartouche, il fait le mouvement de - charger son arme, se couche dans l’herbe à plat ventre, - la tête cachée par un arbre, dans la position d’un - tirailleur, et suit, l’arme épaulée, tous les mouvements - de l’ennemi qu’il croit voir à courte distance.” - -In a subsequent abnormal period, Dr. Mesnet caused the patient to -repeat this scene by placing him in the same conditions. Now, in this -case, the question arises whether the series of actions constituting -this singular pantomime was accompanied by the ordinary states of -consciousness, the appropriate train of ideas, or not? Did the man -dream that he was skirmishing? or was he in the condition of one of -Vaucauson’s automata—a senseless mechanism worked by molecular changes -in his nervous system? The analogy of the frog shows that the latter -assumption is perfectly justifiable. - -The ex-sergeant has a good voice, and had, at one time, been employed -as a singer at a café. In one of his abnormal states he was observed -to begin humming a tune. He then went to his room, dressed himself -carefully, and took up some parts of a periodical novel, which lay on -his bed, as if he were trying to find something. Dr. Mesnet, suspecting -that he was seeking his music, made up one of these into a roll and -put it into his hand. He appeared satisfied, took up his cane and went -down-stairs to the door. Here Dr. Mesnet turned him round, and he -walked quite contentedly, in the opposite direction, towards the room -of the concièrge. The light of the sun shining through a window now -happened to fall upon him, and seemed to suggest the footlights of the -stage on which he was accustomed to make his appearance. He stopped, -opened his roll of imaginary music, put himself into the attitude of a -singer, and sang, with perfect execution, three songs, one after the -other. After which he wiped his face with his handkerchief and drank, -without a grimace, a tumbler of strong vinegar and water which was put -into his hand. - -An experiment which may be performed upon the frog deprived of the -fore part of its brain, well known as Göltz’s “Quak-versuch,” affords -a parallel to this performance. If the skin of a certain part of the -back of such a frog is gently stroked with the finger, it immediately -croaks. It never croaks unless it is so stroked, and the croak always -follows the stroke, just as the sound of a repeater follows the -touching of the spring. In the frog, this “song” is innate—so to speak -_à priori_—and depends upon a mechanism in the brain governing the -vocal apparatus, which is set at work by the molecular change set up in -the sensory nerves of the skin of the back by the contact of a foreign -body. - -In man there is also a vocal mechanism, and the cry of an infant is -in the same sense innate and _à priori_, inasmuch as it depends on an -organic relation between its sensory nerves and the nervous mechanism -which governs the vocal apparatus. Learning to speak, and learning to -sing, are processes by which the vocal mechanism is set to new tunes. -A song which has been learned has its molecular equivalent, which -potentially represents it in the brain, just as a musical box wound up -potentially represents an overture. Touch the stop and the overture -begins; send a molecular impulse along the proper afferent nerve and -the singer begins his song. - -Again, the manner in which the frog, though apparently insensible to -light, is yet, under some circumstances, influenced by visual images, -finds a singular parallel in the case of the ex-sergeant. - -Sitting at a table, in one of his abnormal states, he took up a -pen, felt for paper and ink, and began to write a letter to his -general, in which he recommended himself for a medal, on account of -his good conduct and courage. It occurred to Dr. Mesnet to ascertain -experimentally how far vision was concerned in this act of writing. He -therefore interposed a screen between the man’s eyes and his hands; -under these circumstances he went on writing for a short time, but the -words became illegible, and he finally stopped, without manifesting -any discontent. On the withdrawal of the screen he began to write -again where he had left off. The substitution of water for ink in the -inkstand had a similar result. He stopped, looked at his pen, wiped it -on his coat, dipped it in the water, and began again, with the same -effect. - -On one occasion, he began to write upon the topmost of ten superimposed -sheets of paper. After he had written a line or two, this sheet was -suddenly drawn away. There was a slight expression of surprise, but he -continued his letter on the second sheet exactly as if it had been the -first. This operation was repeated five times, so that the fifth sheet -contained nothing but the writer’s signature at the bottom of the page. -Nevertheless, when the signature was finished, his eyes turned to the -top of the blank sheet, and he went through the form of reading over -what he had written, a movement of the lips accompanying each word; -moreover, with his pen, he put in such corrections as were needed, in -that part of the blank page which corresponded with the position of the -words which required correction, in the sheets which had been taken -away. If the five sheets had been transparent, therefore, they would, -when superposed, have formed a properly written and corrected letter. - -Immediately after he had written his letter, F—— got up, walked down -to the garden, made himself a cigarette, lighted and smoked it. He was -about to prepare another, but sought in vain for his tobacco-pouch, -which had been purposely taken away. The pouch was now thrust before -his eyes and put under his nose, but he neither saw nor smelt it; but, -when it was placed in his hand, he at once seized it, made a fresh -cigarette, and ignited a match to light the latter. The match was blown -out, and another lighted match placed close before his eyes, but he -made no attempt to take it; and, if his cigarette was lighted for him, -he made no attempt to smoke. All this time the eyes were vacant, and -neither winked, nor exhibited any contraction of the pupils. From these -and other experiments, Dr. Mesnet draws the conclusion that his patient -sees some things and not others; that the sense of sight is accessible -to all things which are brought into relation with him by the sense of -touch, and, on the contrary, insensible to things which lie outside -this relation. He sees the match he holds, and does not see any other. - -Just so the frog “sees” the book which is in the way of his jump, at -the same time that isolated visual impressions take no effect upon -him.[53] - -As I have pointed out, it is impossible to prove that F—— is absolutely -unconscious in his abnormal state, but it is no less impossible to -prove the contrary; and the case of the frog goes a long way to -justify the assumption that, in the abnormal state, the man is a mere -insensible machine. - -If such facts as these had come under the knowledge of Descartes, would -they not have formed an apt commentary upon that remarkable passage in -the “Traité de l’Homme,” which I have quoted elsewhere,[54] but which -is worth repetition?— - - “All the functions which I have attributed to this - machine (the body), as the digestion of food, the - pulsation of the heart and of the arteries; the nutrition - and the growth of the limbs; respiration, wakefulness, - and sleep; the reception of light, sounds, odours, - flavours, heat, and such like qualities, in the organs of - the external senses; the impression of the ideas of these - in the organ of common sensation and in the imagination; - the retention or the impression of these ideas on the - memory: the internal movements of the appetites and the - passions; and lastly the external movements of all the - limbs, which follow so aptly, as well the action of - the objects which are presented to the senses, as the - impressions which meet in the memory, that they imitate - as nearly as possible those of a real man; I desire, I - say, that you should consider that these functions in the - machine naturally proceed from the mere arrangement of - its organs, neither more nor less than do the movements - of a clock, or other automaton, from that of its weights - and its wheels; so that, so far as these are concerned, - it is not necessary to conceive any other vegetative or - sensitive soul, nor any other principle of motion or of - life, than the blood and the spirits agitated by the fire - which burns continually in the heart, and which is no - wise essentially different from all the fires which exist - in inanimate bodies.” - -And would Descartes not have been justified in asking why we need deny -that animals are machines, when men, in a state of unconsciousness, -perform, mechanically, actions as complicated and as seemingly rational -as those of any animals? - -But though I do not think that Descartes’ hypothesis can be positively -refuted, I am not disposed to accept it. The doctrine of continuity -is too well established for it to be permissible to me to suppose -that any complex natural phenomenon comes into existence suddenly, -and without being preceded by simpler modifications; and very strong -arguments would be needed to prove that such complex phenomena, as -those of consciousness, first make their appearance in man. We know, -that, in the individual man, consciousness grows from a dim glimmer to -its full light, whether we consider the infant advancing in years, or -the adult emerging from slumber and swoon. We know, further, that the -lower animals possess, though less developed, that part of the brain -which we have every reason to believe to be the organ of consciousness -in man; and as, in other cases, function and organ are proportional, so -we have a right to conclude it is with the brain; and that the brutes, -though they may not possess our intensity of consciousness, and though, -from the absence of language, they can have no trains of thoughts, but -only trains of feelings, yet have a consciousness which, more or less -distinctly, foreshadows our own. - -I confess that, in view of the struggle for existence which goes on -in the animal world, and of the frightful quantity of pain with which -it must be accompanied, I should be glad if the probabilities were in -favour of Descartes’ hypothesis; but, on the other hand, considering -the terrible practical consequences to domestic animals which might -ensue from any error on our part, it is as well to err on the right -side, if we err at all, and deal with them as weaker brethren, who are -bound, like the rest of us, to pay their toll for living, and suffer -what is needful for the general good. As Hartley finely says, “We -seem to be in the place of God to them;” and we may justly follow the -precedents He sets in nature in our dealings with them. - -But though we may see reason to disagree with Descartes’ hypothesis -that brutes are unconscious machines, it does not follow that he -was wrong in regarding them as automata. They may be more or less -conscious, sensitive, automata; and the view that they are such -conscious machines is that which is implicitly, or explicitly, adopted -by most persons. When we speak of the actions of the lower animals -being guided by instinct and not by reason, what we really mean is -that, though they feel as we do, yet their actions are the results -of their physical organisation. We believe, in short, that they are -machines, one part of which (the nervous system) not only sets the rest -in motion, and co-ordinates its movements in relation with changes -in surrounding bodies, but is provided with special apparatus, the -function of which is the calling into existence of those states of -consciousness which are termed sensations, emotions, and ideas. I -believe that this generally accepted view is the best expression of the -facts at present known. - -It is experimentally demonstrable—any one who cares to run a pin into -himself may perform a sufficient demonstration of the fact—that a mode -of motion of the nervous system is the immediate antecedent of a state -of consciousness. All but the adherents of “Occasionalism,” or of the -doctrine of “Pre-established Harmony” (if any such now exist), must -admit that we have as much reason for regarding the mode of motion -of the nervous system as the cause of the state of consciousness, as -we have for regarding any event as the cause of another. How the one -phenomenon causes the other we know, as much or as little, as in any -other case of causation; but we have as much right to believe that the -sensation is an effect of the molecular change, as we have to believe -that motion is an effect of impact; and there is as much propriety in -saying that the brain evolves sensation, as there is in saying that an -iron rod, when hammered, evolves heat. - -As I have endeavoured to show, we are justified in supposing that -something analogous to what happens in ourselves takes place in the -brutes, and that the affections of their sensory nerves give rise to -molecular changes in the brain, which again give rise to, or evolve, -the corresponding states of consciousness. Nor can there be any -reasonable doubt that the emotions of brutes, and such ideas as they -possess, are similarly dependent upon molecular brain changes. Each -sensory impression leaves behind a record in the structure of the -brain—an “ideagenous” molecule, so to speak, which is competent, under -certain conditions, to reproduce, in a fainter condition, the state of -consciousness which corresponds with that sensory impression; and it is -these “ideagenous molecules” which are the physical basis of memory. - -It may be assumed, then, that molecular changes in the brain are the -causes of all the states of consciousness of brutes. Is there any -evidence that these states of consciousness may, conversely, cause -those molecular changes which give rise to muscular motion? I see -no such evidence. The frog walks, hops, swims, and goes through his -gymnastic performances quite as well without consciousness, and -consequently without volition, as with it; and, if a frog, in his -natural state, possesses anything corresponding with what we call -volition, there is no reason to think that it is anything but a -concomitant of the molecular changes in the brain which form part of -the series involved in the production of motion. - -The consciousness of brutes would appear to be related to the mechanism -of their body simply as a collateral product of its working, and to -be as completely without any power of modifying that working as the -steam-whistle which accompanies the work of a locomotive engine is -without influence upon its machinery. Their volition, if they have -any, is an emotion indicative of physical changes, not a cause of such -changes. - -This conception of the relations of states of consciousness with -molecular changes in the brain—of _psychoses_ with _neuroses_—does not -prevent us from ascribing free will to brutes. For an agent is free -when there is nothing to prevent him from doing that which he desires -to do. If a greyhound chases a hare, he is a free agent, because his -action is in entire accordance with his strong desire to catch the -hare; while so long as he is held back by the leash he is not free, -being prevented by external force from following his inclination. -And the ascription of freedom to the greyhound under the former -circumstances is by no means inconsistent with the other aspect of -the facts of the case—that he is a machine impelled to the chase, and -caused, at the same time, to have the desire to catch the game by the -impression which the rays of light proceeding from the hare make upon -his eyes, and through them upon his brain. - -Much ingenious argument has, at various times, been bestowed upon the -question: How is it possible to imagine that volition, which is a state -of consciousness, and, as such, has not the slightest community of -nature with matter in motion, can act upon the moving matter of which -the body is composed, as it is assumed to do in voluntary acts? But -if, as is here suggested, the voluntary acts of brutes—or, in other -words, the acts which they desire to perform—are as purely mechanical -as the rest of their actions, and are simply accompanied by the state -of consciousness called volition, the inquiry, so far as they are -concerned, becomes superfluous. Their volitions do not enter into the -chain of causation of their actions at all. - -The hypothesis that brutes are conscious automata is perfectly -consistent with any view that may be held respecting the often -discussed and curious question whether they have souls or not; and, -if they have souls, whether those souls are immortal or not. It is -obviously harmonious with the most literal adherence to the text -of Scripture concerning “the beast that perisheth;” but it is not -inconsistent with the amiable conviction ascribed by Pope to his -“untutored savage,” that when he passes to the happy hunting-grounds -in the sky, “his faithful dog shall bear him company.” If the brutes -have consciousness and no souls, then it is clear that, in them, -consciousness is a direct function of material changes; while, if -they possess immaterial subjects of consciousness, or souls, then, -as consciousness is brought into existence only as the consequence -of molecular motion of the brain, it follows that it is an indirect -product of material changes. The soul stands related to the body as the -bell of a clock to the works, and consciousness answers to the sound -which the bell gives out when it is struck. - -Thus far I have strictly confined myself to the problem with which I -proposed to deal at starting—the automatism of brutes. The question -is, I believe, a perfectly open one, and I feel happy in running -no risk of either Papal or Presbyterian condemnation for the views -which I have ventured to put forward. And there are so very few -interesting questions which one is, at present, allowed to think out -scientifically—to go as far as reason leads, and stop where evidence -comes to an end—without speedily being deafened by the tattoo of “the -drum ecclesiastic”—that I have luxuriated in my rare freedom, and would -now willingly bring this disquisition to an end if I could hope that -other people would go no farther. Unfortunately, past experience debars -me from entertaining any such hope, even if - - “... that drum’s discordant sound - Parading round and round and round,” - -were not, at present, as audible to me, as it was to the mild poet who -ventured to express his hatred of drums in general, in that well-known -couplet. - -It will be said, that I mean that the conclusions deduced from the -study of the brutes are applicable to man, and that the logical -consequences of such application are fatalism, materialism, and -atheism—whereupon the drums will beat the _pas de charge_. - -One does not do battle with drummers; but I venture to offer a few -remarks for the calm consideration of thoughtful persons, untrammelled -by foregone conclusions, unpledged to shore-up tottering dogmas, and -anxious only to know the true bearings of the case. - -It is quite true that, to the best of my judgment, the argumentation -which applies to brutes holds equally good of men; and, therefore, that -all states of consciousness in us, as in them, are immediately caused -by molecular changes of the brain-substance. It seems to me that in -men, as in brutes, there is no proof that any state of consciousness -is the cause of change in the motion of the matter of the organism. If -these positions are well based, it follows that our mental conditions -are simply the symbols in consciousness of the changes which take -place automatically in the organism; and that, to take an extreme -illustration, the feeling we call volition is not the cause of a -voluntary act, but the symbol of that state of the brain which is -the immediate cause of that act. We are conscious automata, endowed -with free will in the only intelligible sense of that much-abused -term—inasmuch as in many respects we are able to do as we like—but -none the less parts of the great series of causes and effects which, in -unbroken continuity, composes that which is, and has been, and shall -be—the sum of existence. - -As to the logical consequences of this conviction of mine, I may be -permitted to remark that logical consequences are the scarecrows of -fools and the beacons of wise men. The only question which any wise man -can ask himself, and which any honest man will ask himself, is whether -a doctrine is true or false. Consequences will take care of themselves; -at most their importance can only justify us in testing with extra care -the reasoning process from which they result. - -So that if the view I have taken did really and logically lead to -fatalism, materialism, and atheism, I should profess myself a fatalist, -materialist, and atheist; and I should look upon those who, while they -believed in my honesty of purpose and intellectual competency, should -raise a hue and cry against me, as people who by their own admission -preferred lying to truth, and whose opinions therefore were unworthy of -the smallest attention. - -But, as I have endeavoured to explain on other occasions, I really have -no claim to rank myself among fatalistic, materialistic, or atheistic -philosophers. Not among fatalists, for I take the conception of -necessity to have a logical, and not a physical foundation; not among -materialists, for I am utterly incapable of conceiving the existence -of matter if there is no mind in which to picture that existence; not -among atheists, for the problem of the ultimate cause of existence is -one which seems to me to be hopelessly out of reach of my poor powers. -Of all the senseless babble I have ever had occasion to read, the -demonstrations of these philosophers who undertake to tell us all about -the nature of God would be the worst, if they were not surpassed by the -still greater absurdities of the philosophers who try to prove that -there is no God. - -And if this personal disclaimer should not be enough, let me further -point out that a great many persons whose acuteness and learning will -not be contested, and whose Christian piety, and, in some cases, strict -orthodoxy, are above suspicion, have held more or less definitely the -view that man is a conscious automaton. - -It is held, for example, in substance, by the whole school of -predestinarian theologians, typified by St. Augustine, Calvin, and -Jonathan Edwards—the great work of the latter on the will showing -in this, as in other cases, that the growth of physical science has -introduced no new difficulties of principle into theological problems, -but has merely given visible body, as it were, to those which already -existed. - -Among philosophers, the pious Geulincx and the whole school of -occasionalist Cartesians held this view; the orthodox Leibnitz invented -the term “automate spirituel,” and applied it to man; the fervent -Christian, Hartley, was one of the chief advocates and best expositors -of the doctrine; while another zealous apologist of Christianity in -a sceptical age, and a contemporary of Hartley, Charles Bonnet, the -Genevese naturalist, has embodied the doctrine in language of such -precision and simplicity, that I will quote the little-known passage of -his “Essai de Psychologie” at length:— - - -“ANOTHER HYPOTHESIS CONCERNING THE MECHANISM OF IDEAS.[55] - - “Philosophers accustomed to judge of things by that which - they are in themselves, and not by their relation to - received ideas, would not be shocked if they met with - the proposition that the soul is a mere spectator of - the movements of its body: that the latter performs of - itself all that series of actions which constitutes life: - that it moves of itself: that it is the body alone which - reproduces ideas, compares and arranges them; which forms - reasonings, imagines and executes plans of all kinds, - etc. This hypothesis, though perhaps of an excessive - boldness, nevertheless deserves some consideration. - - “It is not to be denied that Supreme Power could create - an automaton which should exactly imitate all the - external and internal actions of man. - - “I understand by external actions, all those movements - which pass under our eyes; I term internal actions, all - the motions which in the natural state cannot be observed - because they take place in the interior of the body—such - as the movements of digestion, circulation, sensation, - etc. Moreover, I include in this category the movements - which give rise to ideas, whatever be their nature. - - “In the automaton which we are considering everything - would be precisely determined. Everything would occur - according to the rules of the most admirable mechanism: - one state would succeed another state, one operation - would lead to another operation, according to invariable - laws; motion would become alternately cause and effect, - effect and cause; reaction would answer to action, and - reproduction to production. - - “Constructed with definite relations to the activity - of the beings which compose the world, the automaton - would receive impressions from it, and, in faithful - correspondence thereto, it would execute a corresponding - series of motions. - - “Indifferent towards any determination, it would yield - equally to all, if the first impressions did not, so to - speak, wind up the machine and decide its operations and - its course. - - “The series of movements which this automaton could - execute would distinguish it from all others formed on - the same model, but which, not having been placed in - similar circumstances, would not have experienced the - same impressions, or would not have experienced them in - the same order. - - “The senses of the automaton, set in motion by the - objects presented to it, would communicate their motion - to the brain, the chief motor apparatus of the machine. - This would put in action the muscles of the hands and - feet, in virtue of their secret connection with the - senses. These muscles, alternately contracted and - dilated, would approximate or remove the automaton from - the objects, in the relation which they would bear to the - conservation or the destruction of the machine. - - “The motions of perception and sensation which the - objects would have impressed on the brain, would be - preserved in it by the energy of its mechanism. They - would become more vivid according to the actual condition - of the automaton, considered in itself and relatively to - the objects. - - “Words being only the motions impressed on the organ - of hearing and that of voice, the diversity of these - movements, their combination, the order in which they - would succeed one another, would represent judgments, - reasoning, and all the operations of the mind. - - “A close correspondence between the organs of the senses, - either by the opening into one another of their nervous - ramifications, or by interposed springs (_ressorts_), - would establish such a connection in their working, that, - on the occasion of the movements impressed on one of - these organs, other movements would be excited, or would - become more vivid in some of the other senses. - - “Give the automaton a soul which contemplates its - movements, which believes itself to be the author of - them, which has different volitions on the occasion of - the different movements, and you will on this hypothesis - construct a man. - - “But would this man be free? Can the feeling of our - liberty, this feeling which is so clear and so distinct - and so vivid as to persuade us that we are the authors of - our actions, be conciliated with this hypothesis? If it - removes the difficulty which attends the conception of - the action of the soul on the body, on the other hand it - leaves untouched that which meets us in endeavouring to - conceive the action of the body on the soul.” - -But if Leibnitz, Jonathan Edwards, and Hartley—men who rank among -the giants of the world of thought—could see no antagonism between -the doctrine under discussion and Christian orthodoxy, is it not -just possible that smaller folk may be wrong in making such a coil -about “logical consequences”? And, seeing how large a share of this -clamour is raised by the clergy of one denomination or another, may -I say, in conclusion, that it really would be well if ecclesiastical -persons would reflect that ordination, whatever deep-seated graces -it may confer, has never been observed to be followed by any visible -increase in the learning or the logic of its subject. Making a man a -Bishop, or entrusting him with the office of ministering to even the -largest of Presbyterian congregations, or setting him up to lecture to -a Church congress, really does not in the smallest degree augment such -title to respect as his opinions may intrinsically possess. And, when -such a man presumes on an authority which was conferred upon him for -other purposes, to sit in judgment upon matters his incompetence to -deal with which is patent, it is permissible to ignore his sacerdotal -pretensions, and to tell him, as one would tell a mere common, -unconsecrated, layman: that it is not necessary for any man to occupy -himself with problems of this kind unless he so choose; life is filled -full enough by the performance of its ordinary and obvious duties. But -that, if a man elect to become a judge of these grave questions; still -more, if he assume the responsibility of attaching praise or blame -to his fellow-men for the conclusions at which they arrive touching -them, he will commit a sin more grievous than most breaches of the -Decalogue, unless he avoid a lazy reliance upon the information that -is gathered by prejudice and filtered through passion, unless he go -back to the prime sources of knowledge—the facts of nature, and the -thoughts of those wise men who for generations past have been her best -interpreters. - - - - -X. - -ON SENSATION AND THE UNITY OF STRUCTURE OF SENSIFEROUS ORGANS. - - -The maxim that metaphysical inquiries are barren of result, and that -the serious occupation of the mind with them is a mere waste of time -and labour, finds much favour in the eyes of the many persons who -pride themselves on the possession of sound common sense; and we -sometimes hear it enunciated by weighty authorities, as if its natural -consequence, the suppression of such studies, had the force of a moral -obligation. - -In this case, however, as in some others, those who lay down the law -seem to forget that a wise legislator will consider, not merely whether -his proposed enactment is desirable, but whether obedience to it is -possible. For, if the latter question is answered negatively, the -former is surely hardly worth debate. - -Here, in fact, lies the pith of the reply to those who would make -metaphysics contraband of intellect. Whether it is desirable to -place a prohibitory duty upon philosophical speculations or not, it -is utterly impossible to prevent the importation of them into the -mind. And it is not a little curious to observe that those who most -loudly profess to abstain from such commodities are, all the while, -unconscious consumers, on a great scale, of one or other of their -multitudinous disguises or adulterations. With mouths full of the -particular kind of heavily buttered toast which they affect, they -inveigh against the eating of plain bread. In truth, the attempt to -nourish the human intellect upon a diet which contains no metaphysics -is about as hopeful as that of certain Eastern sages to nourish their -bodies without destroying life. Everybody has heard the story of the -pitiless microscopist, who ruined the peace of mind of one of these -mild enthusiasts by showing him the animals moving in a drop of the -water with which, in the innocency of his heart, he slaked his thirst; -and the unsuspecting devotee of plain common sense may look for as -unexpected a shock when the magnifier of severe logic reveals the -germs, if not the full-grown shapes, of lively metaphysical postulates -rampant amidst his most positive and matter-of-fact notions. - -By way of escape from the metaphysical Will-o’-the-wisps generated -in the marshes of literature and theology, the serious student is -sometimes bidden to betake himself to the solid ground of physical -science. But the fish of immortal memory, who threw himself out of the -frying-pan into the fire, was not more ill advised than the man who -seeks sanctuary from philosophical persecution within the walls of -the observatory or of the laboratory. It is said that “metaphysics” -owe their name to the fact that, in Aristotle’s works, questions of -pure philosophy are dealt with immediately after those of physics. If -so, the accident is happily symbolical of the essential relations of -things; for metaphysical speculation follows as closely upon physical -theory as black care upon the horseman. - -One need but mention such fundamental, and indeed indispensable, -conceptions of the natural philosopher as those of atoms and forces: -or that of attraction considered as action at a distance; or that of -potential energy; or the antinomies of a vacuum and a plenum; to call -to mind the metaphysical background of physics and chemistry; while, in -the biological sciences, the case is still worse. What is an individual -among the lower plants and animals? Are genera and species realities or -abstractions? Is there such a thing as Vital Force? or does the name -denote a mere relic of metaphysical fetichism? Is the doctrine of final -causes legitimate or illegitimate? These are a few of the metaphysical -topics which are suggested by the most elementary study of biological -facts. But, more than this, it may be truly said that the roots of -every system of philosophy lie deep among the facts of physiology. No -one can doubt that the organs and the functions of sensation are as -much a part of the province of the physiologist, as are the organs and -functions of motion, or those of digestion; and yet it is impossible -to gain an acquaintance with even the rudiments of the physiology of -sensation without being led straight to one of the most fundamental of -all metaphysical problems. In fact, the sensory operations have been, -from time immemorial, the battle-ground of philosophers. - -I have more than once taken occasion to point out that we are -indebted to Descartes, who happened to be a physiologist as well as -a philosopher, for the first distinct enunciation of the essential -elements of the true theory of sensation. In later times, it is not to -the works of the philosophers, if Hartley and James Mill are excepted, -but to those of the physiologists, that we must turn for an adequate -account of the sensory process. Haller’s luminous, though summary, -account of sensation in his admirable “Primæ Lineæ,” the first edition -of which was printed in 1747, offers a striking contrast to the -prolixity and confusion of thought which pervade Reid’s “Inquiry,” of -seventeen years’ later date.[56] Even Sir William Hamilton, learned -historian and acute critic as he was, not only failed to apprehend the -philosophical bearing of long-established physiological truths; but, -when he affirmed that there is no reason to deny that the mind feels at -the finger points, and none to assert that the brain is the sole organ -of thought,[57] he showed that he had not apprehended the significance -of the revolution commenced, two hundred years before his time, by -Descartes, and effectively followed up by Haller, Hartley, and Bonnet, -in the middle of the last century. - -In truth, the theory of sensation, except in one point, is, at the -present moment, very much where Hartley, led by a hint of Sir Isaac -Newton’s, left it, when, a hundred and twenty years since, the -“Observations on Man: his Frame, his Duty, and his Expectations,” was -laid before the world. The whole matter is put in a nutshell in the -following passages of this notable book. - - “External objects impressed upon the senses occasion, - first on the nerves on which they are impressed, and then - on the brain, vibrations of the small and, as we may say, - infinitesimal medullary particles. - - “These vibrations are motions backwards and forwards - of the small particles; of the same kind with the - oscillations of pendulums and the tremblings of the - particles of sounding bodies. They must be conceived to - be exceedingly short and small, so as not to have the - least efficacy to disturb or move the whole bodies of the - nerves or brain.”[58] - - “The white medullary substance of the brain is also the - immediate instrument by which ideas are presented to - the mind; or, in other words, whatever changes are made - in this substance, corresponding changes are made in our - ideas; and _vice versa_.”[59] - -Hartley, like Haller, had no conception of the nature and functions of -the grey matter of the brain. But, if for “white medullary substance,” -in the latter paragraph, we substitute “grey cellular substance,” -Hartley’s propositions embody the most probable conclusions which are -to be drawn from the latest investigations of physiologists. In order -to judge how completely this is the case, it will be well to study some -simple case of sensation, and, following the example of Reid and of -James Mill, we may begin with the sense of smell. Suppose that I become -aware of a musky scent, to which the name of “muskiness” may be given. -I call this an odour, and I class it along with the feelings of light, -colours, sounds, tastes, and the like, among those phenomena which are -known as sensations. To say that I am aware of this phenomenon, or that -I have it, or that it exists, are simply different modes of affirming -the same facts. If I am asked how I know that it exists, I can only -reply that its existence and my knowledge of it are one and the same -thing; in short, that my knowledge is immediate or intuitive, and, as -such, is possessed of the highest conceivable degree of certainty. - -The pure sensation of muskiness is almost sure to be followed by -a mental state which is not a sensation, but a belief, that there -is somewhere close at hand a something on which the existence of -the sensation depends. It may be a musk-deer, or a musk-rat, or a -musk-plant, or a grain of dry musk, or simply a scented handkerchief; -but former experience leads us to believe that the sensation is due to -the presence of one or other of these objects, and that it will vanish -if the object is removed. In other words, there arises a belief in an -external cause of the muskiness, which, in common language, is termed -an odorous body. - -But the manner in which this belief is usually put into words is -strangely misleading. If we are dealing with a musk-plant, for example, -we do not confine ourselves to a simple statement of that which we -believe, and say that the musk-plant is the cause of the sensation -called muskiness; but we say that the plant has a musky smell, and -we speak of the odour as a quality, or property, inherent in the -plant. And the inevitable reaction of words upon thought has in this -case become so complete, and has penetrated so deeply, that when an -accurate statement of the case—namely, that muskiness, inasmuch as -the term denotes nothing but a sensation, is a mental state, and has -no existence except as a mental phenomenon—is first brought under the -notice of common-sense folks, it is usually regarded by them as what -they are pleased to call a mere metaphysical paradox and a patent -example of useless subtlety. Yet the slightest reflection must suffice -to convince any one possessed of sound reasoning faculties, that it is -as absurd to suppose that muskiness is a quality inherent in one plant, -as it would be to imagine that pain is a quality inherent in another, -because we feel pain when a thorn pricks the finger. - -Even the common-sense philosopher, _par excellence_, says of smell: “It -appears to be a simple and original affection or feeling of the mind, -altogether inexplicable and unaccountable. It is indeed impossible that -it can be in any body: it is a sensation, and a sensation can only be -in a sentient thing.”[60] - -That which is true of muskiness is true of every other odour. -Lavender-smell, clove-smell, garlic-smell, are, like “muskiness,” names -of states of consciousness, and have no existence except as such. -But, in ordinary language, we speak of all these odours as if they -were independent entities residing in lavender, cloves, and garlic; -and it is not without a certain struggle that the false metaphysic of -so-called common sense, thus ingrained in us, is expelled. - -For the present purpose, it is unnecessary to inquire into the origin -of our belief in external bodies, or into that of the notion of -causation. Assuming the existence of an external world, there is no -difficulty in obtaining experimental proof that, as a general rule, -olfactory sensations are caused by odorous bodies; and we may pass on -to the next step of the inquiry—namely, how the odorous body produces -the effect attributed to it. - -The first point to be noted here is another fact revealed by -experience; that the appearance of the sensation is governed, not only -by the presence of the odorous substance, but by the condition of a -certain part of our corporeal structure, the nose. If the nostrils are -closed, the presence of the odorous substance does not give rise to -the sensation; while, when they are open, the sensation is intensified -by the approximation of the odorous substance to them, and by snuffing -up the adjacent air in such a manner as to draw it into the nose. On -the other hand, looking at an odorous substance, or rubbing it on the -skin, or holding it to the ear, does not awaken the sensation. Thus, -it can be readily established by experiment that the perviousness of -the nasal passages is, in some way, essential to the sensory function; -in fact, that the organ of that function is lodged somewhere in the -nasal passages. And, since odorous bodies give rise to their effects at -considerable distances, the suggestion is obvious that something must -pass from them into the sense organ. What is this “something,” which -plays the part of an intermediary between the odorous body and the -sensory organ? - -The oldest speculation about the matter dates back to Democritus and -the Epicurean School, and it is to be found fully stated in the fourth -book of Lucretius. It comes to this: that the surfaces of bodies -are constantly throwing off excessively attenuated films of their -own substance: and that these films, reaching the mind, excite the -appropriate sensations in it. - -Aristotle did not admit the existence of any such material films, but -conceived that it was the form of the substance, and not its matter, -which affected sense, as a seal impresses wax, without losing anything -in the process. While many, if not the majority, of the Schoolmen took -up an intermediate position and supposed that a something, which was -not exactly either material or immaterial, and which they called an -“intentional species,” effected the needful communication between the -bodily cause of sensation and the mind. - -But all these notions, whatever may be said for or against them in -general, are fundamentally defective, by reason of an oversight -which was inevitable, in the state of knowledge at the time in which -they were promulgated. What the older philosophers did not know, and -could not know, before the anatomist and the physiologist had done -their work, is that, between the external object and that mind in -which they supposed the sensation to inhere, there lies a physical -obstacle. The sense organ is not a mere passage by which the “tenuia -simulacra rerum,” or the “intentional species” cast off by objects, -or the “forms” of sensible things, pass straight to the mind; on the -contrary, it stands as a firm and impervious barrier, through which no -material particle of the world without can make its way to the world -within. - -Let us consider the olfactory sense organ more nearly. Each of the -nostrils leads into a passage completely separated from the other -by a partition, and these two passages place the nostrils in free -communication with the back of the throat, so that they freely transmit -the air passing to the lungs when the mouth is shut, as in ordinary -breathing. The floor of each passage is flat, but its roof is a high -arch, the crown of which is seated between the orbital cavities of the -skull, which serve for the lodgment and protection of the eyes; and -it therefore lies behind the apparent limits of that feature which, -in ordinary language, is called the nose. From the side walls of the -upper and back part of these arched chambers, certain delicate plates -of bone project, and these, as well as a considerable part of the -partition between the two chambers, are covered by a fine, soft, moist -membrane. It is to this “Schneiderian,” or olfactory, membrane that -odorous bodies must obtain direct access, if they are to give rise -to their appropriate sensations; and it is upon the relatively large -surface, which the olfactory membrane offers, that we must seek for -the seat of the organ of the olfactory sense. The only essential part -of that organ consists of a multitude of minute rod-like bodies, set -perpendicularly to the surface of the membrane, and forming a part of -the cellular coat, or epithelium, which covers the olfactory membrane, -as the epidermis covers the skin. In the case of the olfactory sense, -there can be no doubt that the Democritic hypothesis, at any rate for -such odorous substances as musk, has a good foundation. Infinitesimal -particles of musk fly off from the surface of the odorous body, and, -becoming diffused through the air, are carried into the nasal passages, -and thence into the olfactory chambers, where they come into contact -with the filamentous extremities of the delicate olfactory epithelium. - -But this is not all. The “mind” is not, so to speak, upon the other -side of the epithelium. On the contrary, the inner ends of the -olfactory cells are connected with nerve fibres, and these nerve -fibres, passing into the cavity of the skull, at length end in a -part of the brain, the olfactory sensorium. It is certain that the -integrity of each, and the physical inter-connection of all these three -structures, the epithelium of the sensory organ, the nerve fibres, -and the sensorium, are essential conditions of ordinary sensation. -That is to say, the air in the olfactory chambers may be charged with -particles of musk; but, if either the epithelium, or the nerve fibres, -or the sensorium is injured, or if they are physically disconnected -from one another, sensation will not arise. Moreover, the epithelium -may be said to be receptive, the nerve fibres transmissive, and the -sensorium sensifacient. For, in the act of smelling, the particles of -the odorous substance produce a molecular change (which Hartley was in -all probability right in terming a vibration) in the epithelium, and -this change being transmitted to the nerve fibres, passes along them -with a measurable velocity, and, finally reaching the sensorium, is -immediately followed by the sensation. - -Thus, modern investigation supplies a representative of the Epicurean -simulacra in the volatile particles of the musk; but it also gives us -the stamp of the particles on the olfactory epithelium, without any -transmission of matter, as the equivalent of the Aristotelian “form;” -while, finally, the modes of motion of the molecules of the olfactory -cells, of the nerve, and of the cerebral sensorium, which are Hartley’s -vibrations, may stand very well for a double of the “intentional -species” of the Schoolmen. And this last remark is not intended merely -to suggest a fanciful parallel; for, if the cause of the sensation is, -as analogy suggests, to be sought in the mode of motion of the object -of sense, then it is quite possible that the particular mode of motion -of the object is reproduced in the sensorium; exactly as the diaphragm -of a telephone reproduces the mode of motion taken up at its receiving -end. In other words, the secondary “intentional species” may be, as the -Schoolmen thought the primary one was, the last link between matter and -mind. - -None the less, however, does it remain true that no similarity exists, -nor indeed is conceivable, between the cause of the sensation and the -sensation. Attend as closely to the sensations of muskiness, or any -other odour, as we will, no trace of extension, resistance, or motion -is discernible in them. They have no attribute in common with those -which we ascribe to matter; they are, in the strictest sense of the -words, immaterial entities. - -Thus, the most elementary study of sensation justifies Descartes’ -position, that we know more of mind than we do of body; that the -immaterial world is a firmer reality than the material. For the -sensation “muskiness” is known immediately. So long as it persists, -it is a part of what we call our thinking selves, and its existence -lies beyond the possibility of doubt. The knowledge of an objective or -material cause of the sensation, on the other hand, is mediate; it is -a belief as contradistinguished from an intuition; and it is a belief -which, in any given instance of sensation, may, by possibility, be -devoid of foundation. For odours, like other sensations, may arise from -the occurrence of the appropriate molecular changes in the nerve or in -the sensorium, by the operation of a cause distinct from the affection -of the sense organ by an odorous body. Such “subjective” sensations -are as real existences as any others, and as distinctly suggest an -external odorous object as their cause; but the belief thus generated -is a delusion. And, if beliefs are properly termed “testimonies of -consciousness,” then undoubtedly the testimony of consciousness may be, -and often is, untrustworthy. - -Another very important consideration arises out of the facts as they -are now known. That which, in the absence of a knowledge of the -physiology of sensation, we call the cause of the smell, and term the -odorous object, is only such, mediately, by reason of its emitting -particles which give rise to a mode of motion in the sense organ. The -sense organ, again, is only a mediate cause by reason of its producing -a molecular change in the nerve fibre; while this last change is also -only a mediate cause of sensation, depending, as it does, upon the -change which it excites in the sensorium. - -The sense organ, the nerve, and the sensorium, taken together, -constitute the sensiferous apparatus. They make up the thickness of the -wall between the mind, as represented by the sensation “muskiness,” and -the object, as represented by the particle of musk in contact with the -olfactory epithelium. - -It will be observed that the sensiferous wall and the external world -are of the same nature; whatever it is that constitutes them both is -expressible in terms of matter and motion. Whatever changes take place -in the sensiferous apparatus are continuous with, and similar to, those -which take place in the external world.[61] But, with the sensorium, -matter and motion come to an end; while phenomena of another order, -or immaterial states of consciousness, make their appearance. How is -the relation between the material and the immaterial phenomena to -be conceived? This is the metaphysical problem of problems, and the -solutions which have been suggested have been made the corner-stones of -systems of philosophy. Three mutually irreconcilable readings of the -riddle have been offered. - -The first is, that an immaterial substance of mind exists; and that it -is affected by the mode of motion of the sensorium in such a way as to -give rise to the sensation. - -The second is, that the sensation is a direct effect of the mode of -motion of the sensorium, brought about without the intervention of any -substance of mind. - -The third is, that the sensation is neither directly nor indirectly -an effect of the mode of motion of the sensorium, but that it has an -independent cause. Properly speaking, therefore, it is not an effect of -the motion of the sensorium, but a concomitant of it. - -As none of these hypotheses is capable of even an approximation to -demonstration, it is almost needless to remark that they have been -severally held with tenacity and advocated with passion. I do not -think it can be said of any of the three that it is inconceivable, or -that it can be assumed on _à priori_ grounds to be impossible. - -Consider the first, for example; an immaterial substance is perfectly -conceivable. In fact, it is obvious that, if we possessed no sensations -but those of smell and hearing, we should be unable to conceive a -material substance. We might have a conception of time, but could -have none of extension, or of resistance, or of motion. And without -the three latter conceptions no idea of matter could be formed. Our -whole knowledge would be limited to that of a shifting succession -of immaterial phenomena. But, if an immaterial substance may exist, -it may have any conceivable properties; and sensation may be one of -them. All these propositions may be affirmed with complete dialectic -safety, inasmuch as they cannot possibly be disproved; but neither -can a particle of demonstrative evidence be offered in favour of the -existence of an immaterial substance. - -As regards the second hypothesis, it certainly is not inconceivable, -and therefore it may be true, that sensation is the direct effect of -certain kinds of bodily motion. It is just as easy to suppose this as -to suppose, on the former hypothesis, that bodily motion affects an -immaterial substance. But neither is it susceptible of proof. - -And, as to the third hypothesis, since the logic of induction is in no -case competent to prove that events apparently standing in the relation -of cause and effect may not both be effects of a common cause—that -also is as safe from refutation, if as incapable of demonstration, as -the other two. - -In my own opinion, neither of these speculations can be regarded -seriously as anything but a more or less convenient working hypothesis. -But, if I must choose among them, I take the “law of parsimony” for my -guide, and select the simplest—namely, that the sensation is the direct -effect of the mode of motion of the sensorium. It may justly be said -that this is not the slightest explanation of sensation; but then am -I really any the wiser, if I say that a sensation is an activity (of -which I know nothing) of a substance of mind (of which also I know -nothing)? Or, if I say that the Deity causes the sensation to arise in -my mind immediately after He has caused the particles of the sensorium -to move in a certain way, is anything gained? In truth, a sensation, as -we have already seen, is an intuition—a part of immediate knowledge. -As such, it is an ultimate fact and inexplicable; and all that we -can hope to find out about it, and that indeed is worth finding out, -is its relation to other natural facts. That relation appears to me -to be sufficiently expressed, for all practical purposes, by saying -that sensation is the invariable consequent of certain changes in the -sensorium—or, in other words, that, so far as we know, the change in -the sensorium is the cause of the sensation. - -I permit myself to imagine that the untutored, if noble, savage of -“common sense” who has been misled into reading thus far by the hope -of getting positive solid information about sensation, giving way to -not unnatural irritation, may here interpellate: “The upshot of all -this long disquisition is that we are profoundly ignorant. We knew -that to begin with, and you have merely furnished another example of -the emptiness and uselessness of metaphysics.” But I venture to reply, -Pardon me, you were ignorant, but you did not know it. On the contrary, -you thought you knew a great deal, and were quite satisfied with the -particularly absurd metaphysical notions which you were pleased to -call the teachings of common sense. You thought that your sensations -were properties of external things, and had an existence outside of -yourself. You thought that you knew more about material than you do -about immaterial existences. And if, as a wise man has assured us, -the knowledge of what we don’t know is the next best thing to the -knowledge of what we do know, this brief excursion into the province of -philosophy has been highly profitable. - -Of all the dangerous mental habits, that which schoolboys call -“cocksureness” is probably the most perilous; and the inestimable -value of metaphysical discipline is that it furnishes an effectual -counterpoise to this evil proclivity. Whoso has mastered the elements -of philosophy knows that the attribute of unquestionable certainty -appertains only to the existence of a state of consciousness so long -as it exists; all other beliefs are mere probabilities of a higher or -lower order. Sound metaphysic is an amulet which renders its possessor -proof alike against the poison of superstition and the counter-poison -of nihilism; by showing that the affirmations of the former and the -denials of the latter alike deal with matters about which, for lack of -evidence, nothing can be either affirmed or denied. - - -I have dwelt at length upon the nature and origin of our sensations of -smell, on account of the comparative freedom of the olfactory sense -from the complications which are met with in most of the other senses. - -Sensations of taste, however, are generated in almost as simple a -fashion as those of smell. In this case, the sense organ is the -epithelium which covers the tongue and the palate: and which sometimes, -becoming modified, gives rise to peculiar organs termed “gustatory -bulbs,” in which the epithelial cells elongate and assume a somewhat -rod-like form. Nerve fibres connect the sensory organ with the -sensorium, and tastes or flavours are states of consciousness caused -by the change of molecular state of the latter. In the case of the -sense of touch there is often no sense organ distinct from the general -epidermis. But many fishes and amphibia exhibit local modifications -of the epidermic cells which are sometimes extraordinarily like the -gustatory bulbs; more commonly, both in lower and higher animals, -the effect of the contact of external bodies is intensified by the -development of hair-like filaments, or of true hairs, the bases of -which are in immediate relation with the ends of the sensory nerves. -Every one must have noticed the extreme delicacy of the sensations -produced by the contact of bodies with the ends of the hairs of the -head; and the “whiskers” of cats owe their functional importance to -the abundant supply of nerves to the follicles in which their bases -are lodged. What part, if any, the so-called “tactile corpuscles,” -“end bulbs,” and “Pacinian bodies,” play in the mechanism of touch is -unknown. If they are sense organs, they are exceptional in character, -in so far as they do not appear to be modifications of the epidermis. -Nothing is known respecting the organs of those sensations of -resistance which are grouped under the head of the muscular sense; -nor of the sensations of warmth and cold; nor of that very singular -sensation which we call tickling. - -In the case of heat and cold, the organism not only becomes affected -by external bodies, far more remote than those which affect the -sense of smell; but the Democritic hypothesis is obviously no longer -permissible. When the direct rays of the sun fall upon the skin, -the sensation of heat is certainly not caused by “attenuated films” -thrown off from that luminary, but is due to a mode of motion which is -transmitted to us. In Aristotelian phrase, it is the form without the -matter of the sun which stamps the sense organ; and this, translated -into modern language, means nearly the same thing as Hartley’s -vibrations. Thus we are prepared for what happens in the case of -the auditory and the visual senses. For neither the ear, nor the -eye, receives anything but the impulses or vibrations originated by -sonorous or luminous bodies. Nevertheless, the receptive apparatus -still consists of nothing but specially modified epithelial cells. -In the labyrinth of the ear of the higher animals, the free ends of -these cells terminate in excessively delicate hair-like filaments; -while, in the lower forms of auditory organ, its free surface is -beset with delicate hairs like those of the surface of the body, and -the transmissive nerves are connected with the bases of these hairs. -Thus there is an insensible gradation in the forms of the receptive -apparatus, from the organ of touch, on the one hand, to those of taste -and smell; and, on the other hand, to that of hearing. Even in the -case of the most refined of all the sense organs, that of vision, the -receptive apparatus departs but little from the general type. The -only essential constituent of the visual sense organ is the retina, -which forms so small a part of the eyes of the higher animals; and the -simplest eyes are nothing but portions of the integument, in which -the cells of the epidermis have become converted into glassy rod-like -retinal corpuscles. The outer ends of these are turned towards the -light; their sides are more or less extensively coated with a dark -pigment, and their inner ends are connected with the transmissive nerve -fibres. The light, impinging on these visual rods, produces a change in -them which is communicated to the nerve fibres, and, being transmitted -to the sensorium, gives rise to the sensation—if indeed all animals -which possess eyes are endowed with what we understand as sensation. - -In the higher animals, a complicated apparatus of lenses, arranged -on the principle of a camera obscura, serves at once to concentrate -and to individualise the pencils of light proceeding from external -bodies. But the essential part of the organ of vision is still a layer -of cells, which have the form of rods with truncated or conical ends. -By what seems a strange anomaly, however, the glassy ends of these are -turned not towards, but away from, the light; and the latter has to -traverse the layer of nervous tissues with which their outer ends are -connected, before it can affect them. Moreover, the rods and cones of -the vertebrate retina are so deeply seated, and in many respects so -peculiar in character, that it appears impossible, at first sight, that -they can have anything to do with that epidermis of which gustatory and -tactile, and at any rate the lower forms of auditory and visual, organs -are obvious modifications. - -Whatever be the apparent diversities among the sensiferous apparatuses, -however, they share certain common characters. Each consists of a -receptive, a transmissive, and a sensificatory portion. The essential -part of the first is an epithelium, of the second, nerve fibres, of the -third, a part of the brain; the sensation is always the consequence -of the mode of motion excited in the receptive, and sent along the -transmissive, to the sensificatory part of the sensiferous apparatus. -And, in all the senses, there is no likeness whatever between the -object of sense, which is matter in motion, and the sensation, which is -an immaterial phenomenon. - -On the hypothesis which appears to me to be the most convenient, -sensation is a product of the sensiferous apparatus caused by certain -modes of motion which are set up in it by impulses from without. The -sensiferous apparatuses are, as it were, factories, all of which at -the one end receive raw materials of a similar kind—namely, modes of -motion—while, at the other, each turns out a special product, the -feeling which constitutes the kind of sensation characteristic of it. - -Or, to make use of a closer comparison, each sensiferous apparatus is -comparable to a musical-box wound up; with as many tunes as there are -separate sensations. The object of a simple sensation is the agent -which presses down the stop of one of these tunes, and the more feeble -the agent, the more delicate must be the mobility of the stop.[62] - -But, if this be true, if the recipient part of the sensiferous -apparatus is, in all cases, merely a mechanism affected by coarser or -finer kinds of material motion, we might expect to find that all sense -organs are fundamentally alike, and result from the modification of the -same morphological elements. And this is exactly what does result from -all recent histological and embryological investigations. - -It has been seen that the receptive part of the olfactory apparatus is -a slightly modified epithelium, which lines an olfactory chamber deeply -seated between the orbits in adult human beings. But, if we trace back -the nasal chambers to their origin in the embryo, we find, that, to -begin with, they are mere depressions of the skin of the fore part -of the head, lined by a continuation of the general epidermis. These -depressions become pits, and the pits, by the growth of the adjacent -parts, gradually acquire the position which they finally occupy. The -olfactory organ, therefore, is a specially modified part of the general -integument. - -The human ear would seem to present greater difficulties. For the -essential part of the sense organ, in this case, is the membranous -labyrinth, a bag of complicated form, which lies buried in the depths -of the floor of the skull, and is surrounded by dense and solid bone. -Here, however, recourse to the study of development readily unravels -the mystery. Shortly after the time when the olfactory organ appears, -as a depression of the skin on the side of the fore part of the head, -the auditory organ appears as a similar depression on the side of its -back part. The depression, rapidly deepening, becomes a small pouch; -and then, the communication with the exterior becoming shut off, the -pouch is converted into a closed bag, the epithelial lining of which is -a part of the general epidermis segregated from the rest. The adjacent -tissues, changing first into cartilage and then into bone, enclose -the auditory sac in a strong case, in which it undergoes its further -metamorphoses; while the drum, the ear bones, and the external ear, -are superadded by no less extraordinary modifications of the adjacent -parts. Still more marvellous is the history of the development of the -organ of vision. In the place of the eye, as in that of the nose and -that of the ear, the young embryo presents a depression of the general -integument; but, in man and the higher animals, this does not give -rise to the proper sensory organ, but only to part of the accessory -structures concerned in vision. In fact, this depression, deepening -and becoming converted into a shut sac, produces only the cornea, the -aqueous humour, and the crystalline lens of the perfect eye. - -The retina is added to this by the outgrowth of the wall of a portion -of the brain into a sort of bag, or sac, with a narrow neck, the convex -bottom of which is turned outwards, or towards the crystalline lens. -As the development of the eye proceeds, the convex bottom of the bag -becomes pushed in, so that it gradually obliterates the cavity of the -sac, the previously convex wall of which becomes deeply concave. The -sac of the brain is now like a double nightcap ready for the head, but -the place which the head would occupy is taken by the vitreous humour, -while the layer of nightcap next it becomes the retina. The cells of -this layer which lie farthest from the vitreous humour, or, in other -words, bound the original cavity of the sac, are metamorphosed into -the rods and cones. Suppose now that the sac of the brain could be -brought back to its original form; then the rods and cones would form -part of the lining of a side pouch of the brain. But one of the most -wonderful revelations of embryology is the proof of the fact that the -brain itself is, at its first beginning, merely an infolding of the -epidermic layer of the general integument. Hence it follows that the -rods and cones of the vertebrate eye are modified epidermic cells, as -much as the crystalline cones of the insect or crustacean eye are; and -that the inversion of the position of the former in relation to light -arises simply from the roundabout way in which the vertebrate retina is -developed. - -Thus all the higher sense organs start from one foundation, and the -receptive epithelium of the eye, or of the ear, is as much modified -epidermis as is that of the nose. The structural unity of the sense -organs is the morphological parallel to their identity of physiological -function, which, as we have seen, is to be impressed by certain modes -of motion; and they are fine or coarse, in proportion to the delicacy -or the strength of the impulses by which they are to be affected. - - -In ultimate analysis, then, it appears that a sensation is the -equivalent in terms of consciousness for a mode of motion of the matter -of the sensorium. But, if inquiry is pushed a stage farther, and the -question is asked, What then do we know about matter and motion? there -is but one reply possible. All that we know about motion is that it is -a name for certain changes in the relations of our visual, tactile, and -muscular sensations; and all that we know about matter is that it is -the hypothetical substance of physical phenomena—the assumption of the -existence of which is as pure a piece of metaphysical speculation as is -that of the existence of the substance of mind. - -Our sensations, our pleasures, our pains, and the relations of these, -make up the sum total of the elements of positive, unquestionable -knowledge. We call a large section of these sensations and their -relations matter and motion; the rest we term mind and thinking; and -experience shows that there is a certain constant order of succession -between some of the former and some of the latter. - -This is all that just metaphysical criticism leaves of the idols -set up by the spurious metaphysics of vulgar common sense. It is -consistent either with pure Materialism, or with pure Idealism, but -it is neither. For the Idealist, not content with declaring the truth -that our knowledge is limited to facts of consciousness, affirms the -wholly unprovable proposition that nothing exists beyond these and the -substance of mind. And, on the other hand, the Materialist, holding by -the truth that, for anything that appears to the contrary, material -phenomena are the causes of mental phenomena, asserts his unprovable -dogma, that material phenomena and the substance of matter are the sole -primary existences. - -Strike out the propositions about which neither controversialist does -or can know anything, and there is nothing left for them to quarrel -about. Make a desert of the Unknowable, and the divine Astræa of -philosophic peace will commence her blessed reign. - - - - -XI. - -EVOLUTION IN BIOLOGY. - - -In the former half of the eighteenth century, the term “evolution” was -introduced into biological writings, in order to denote the mode in -which some of the most eminent physiologists of that time conceived -that the generation of living things took place; in opposition to the -hypothesis advocated, in the preceding century, by Harvey in that -remarkable work[63] which would give him a claim to rank among the -founders of biological science, even had he not been the discoverer of -the circulation of the blood. - -One of Harvey’s prime objects is to defend and establish, on the -basis of direct observation, the opinion already held by Aristotle; -that, in the higher animals at any rate, the formation of the new -organism by the process of generation takes place, not suddenly, by -simultaneous accretion of rudiments of all, or of the most important, -of the organs of the adult; nor by sudden metamorphosis of a formative -substance into a miniature of the whole, which subsequently grows; -but by _epigenesis_, or successive differentiation of a relatively -homogeneous rudiment into the parts and structures which are -characteristic of the adult. - - “Et primò, quidem, quoniam per _epigenesin_ sive - partium superexorientium additamentum pullum fabricari - certum est: quænam pars ante alias omnes exstruatur, - et quid de illa ejusque generandi modo observandum - veniat, dispiciemus. Ratum sane est et in ovo manifestè - apparet quod _Aristoteles_ de perfectorum animalium - generatione enuntiat: nimirum, non omnes partes - simul fieri, sed ordine aliam post aliam; primùmque - existere particulam genitalem, cujus virtute postea - (tanquam ex principio quodam) reliquæ omnes partes - prosiliant. Qualem in plantarum seminibus (fabis, - putà, aut glandibus) gemmam sive apicem protuberantem - cernimus, totius futuræ arboris principium. _Estque - hæc particula velut filius emancipatus seorsumque - collocatus, et principium per se vivens; unde postea - membrorum ordo describitur; et quæcunque ad absolvendum - animal pertinent, disponuntur._[64] Quoniam enim _nulla - pars se ipsam generat; sed postquam generata est, se - ipsam jam auget; ideo eam primùm oriri necesse est, quæ - principium augendi contineat (sive enim planta, sive - animal est, æque omnibus inest quod vim habeat vegetandi, - sive nutriendi)_,[65] simulque reliquas omnes partes - suo quamque ordine distinguat et formet; proindeque - in eadem primogenita particula anima primario inest, - sensus, motusque, et totius vitæ auctor et principium.” - (Exercitatio 51.) - -Harvey proceeds to contrast this view with that of the “Medici,” or -followers of Hippocrates and Galen, who, “badly philosophising,” -imagined that the brain, the heart, and the liver were simultaneously -first generated in the form of vesicles; and, at the same time, while -expressing his agreement with Aristotle in the principle of epigenesis, -he maintains that it is the blood which is the primal generative part, -and not, as Aristotle thought, the heart. - -In the latter part of the seventeenth century, the doctrine of -epigenesis, thus advocated by Harvey, was controverted, on the ground -of direct observation, by Malpighi, who affirmed that the body of -the chick is to be seen in the egg, before the _punctum sanguineum_ -makes its appearance. But, from this perfectly correct observation -a conclusion which is by no means warranted was drawn; namely, that -the chick, as a whole, really exists in the egg antecedently to -incubation; and that what happens in the course of the latter process -is no addition of new parts, “alias post alias natas,” as Harvey puts -it, but a simple expansion, or unfolding, of the organs which already -exist, though they are too small and inconspicuous to be discovered. -The weight of Malpighi’s observations therefore fell into the scale of -that doctrine which Harvey terms _metamorphosis_, in contradistinction -to epigenesis. - -The views of Malpighi were warmly welcomed, on philosophical grounds, -by Leibnitz,[66] who found in them a support to his hypothesis -of monads, and by Malebranche;[67] while, in the middle of the -eighteenth century, not only speculative considerations, but a -great number of new and interesting observations on the phenomena -of generation, led the ingenious Bonnet, and Haller,[68] the first -physiologist of the age, to adopt, advocate, and extend them. - -Bonnet affirms that, before fecundation, the hen’s egg contains an -excessively minute but complete chick; and that fecundation and -incubation simply cause this germ to absorb nutritious matters, which -are deposited in the interstices of the elementary structures of which -the miniature chick, or germ, is made up. The consequence of this -intussusceptive growth is the “development” or “evolution” of the germ -into the visible bird. Thus an organised individual (_tout organisé_) -“is a composite body consisting of the original, or _elementary_, -parts and of the matters which have been associated with them by the -aid of nutrition;” so that, if these matters could be extracted from -the individual (_tout_), it would, so to speak, become concentrated -in a point, and would thus be restored to its primitive condition of -a _germ_; “just as by extracting from a bone the calcareous substance -which is the source of its hardness, it is reduced to its primitive -state of gristle or membrane.”[69] - -“Evolution” and “development” are, for Bonnet, synonymous terms; and -since by “evolution” he means simply the expansion of that which was -invisible into visibility, he was naturally led to the conclusion, -at which Leibnitz had arrived by a different line of reasoning, that -no such thing as generation, in the proper sense of the word, exists -in nature. The growth of an organic being is simply a process of -enlargement, as a particle of dry gelatine may be swelled up by the -intussusception of water; its death is a shrinkage, such as the swelled -jelly might undergo on desiccation. Nothing really new is produced -in the living world, but the germs which develop have existed since -the beginning of things; and nothing really dies, but, when what we -call death takes place, the living thing shrinks back into its germ -state.[70] - -The two parts of Bonnet’s hypothesis, namely, the doctrine that all -living things proceed from pre-existing germs, and that these contain, -one inclosed within the other, the germs of all future living things, -which is the hypothesis of “_emboîtement_;” and the doctrine that every -germ contains in miniature all the organs of the adult, which is the -hypothesis of evolution or development, in the primary senses of these -words, must be carefully distinguished. In fact, while holding firmly -by the former, Bonnet more or less modified the latter in his later -writings, and, at length, he admits that a “germ” need not be an actual -miniature of the organism; but that it may be merely an “original -preformation” capable of producing the latter.[71] - -But, thus defined, the germ is neither more nor less than the -“particula genitalis” of Aristotle, or the “primordium vegetale” or -“ovum” of Harvey; and the “evolution” of such a germ would not be -distinguishable from “epigenesis.” - -Supported by the great authority of Haller, the doctrine of evolution, -or development, prevailed throughout the whole of the eighteenth -century, and Cuvier appears to have substantially adopted Bonnet’s -later views, though probably he would not have gone all lengths in -the direction of “emboîtement.” In a well-known note to Laurillards’ -“Éloge,” prefixed to the last edition of the “Ossemens fossiles,” the -“radical de l’être” is much the same thing as Aristotle’s “particula -genitalis” and Harvey’s “ovum.”[72] - -Bonnet’s eminent contemporary, Buffon, held nearly the same views -with respect to the nature of the germ, and expresses them even more -confidently.[73] - - “Ceux qui ont cru que le cœur étoit le premier formé, - se sont trompés; ceux qui disent que c’est le sang se - trompent aussi: tout est formé en même temps. Si l’on ne - consulte que l’observation, le poulet se voit dans l’œuf - avant qui’il ait été couvé.” - - “J’ai ouvert une grande quantité d’œufs à differens temps - avant et après l’incubation, et je me suis convaincu par - mes yeux que le poulet existe en entier dans le milieu - de la cicatricule au moment qu’il sort du corps de la - poule.”[74] - -The “moule intérieur” of Buffon is the aggregate of elementary -parts which constitute the individual, and is thus the equivalent -of Bonnet’s germ,[75] as defined in the passage cited above. But -Buffon further imagined that innumerable “molecules organiques” are -dispersed throughout the world, and that alimentation consists in the -appropriation by the parts of an organism of those molecules which -are analogous to them. Growth, therefore, was, on this hypothesis, a -process partly of simple evolution, and partly of what has been termed -“syngenesis.” Buffon’s opinion is, in fact, a sort of combination of -views, essentially similar to those of Bonnet, with others, somewhat -similar to those of the “Medici” whom Harvey condemns. The “molecules -organiques” are physical equivalents of Leibnitz’s “monads.” - -It is a striking example of the difficulty of getting people to use -their own powers of investigation accurately, that this form of the -doctrine of evolution should have held its ground so long; for it was -thoroughly and completely exploded, not long after its enunciation, by -Caspar Friederich Wolff, who in his “Theoria Generationis,” published -in 1759, placed the opposite theory of epigenesis upon the secure -foundation of fact, from which it has never been displaced. But Wolff -had no immediate successors. The school of Cuvier was lamentably -deficient in embryologists; and it was only in the course of the -first thirty years of the present century, that Prévost and Dumas in -France, and, later on, Döllinger, Pander, Von Bär, Rathke, and Remak -in Germany, founded modern embryology; while, at the same time, they -proved the utter incompatibility of the hypothesis of evolution, as -formulated by Bonnet and Haller, with easily demonstrable facts. - -Nevertheless, though the conceptions originally denoted by “evolution” -and “development” were shown to be untenable, the words retained -their application to the process by which the embryos of living -beings gradually make their appearance; and the terms “Development,” -“Entwickelung,” and “Evolutio,” are now indiscriminately used for -the series of genetic changes exhibited by living beings, by writers -who would emphatically deny that “Development” or “Entwickelung” or -“Evolutio,” in the sense in which these words were usually employed by -Bonnet or by Haller, ever occurs. - -Evolution, or development, is, in fact, at present employed in biology -as a general name for the history of the steps by which any living -being has acquired the morphological and the physiological characters -which distinguish it. As civil history may be divided into biography, -which is the history of individuals, and universal history, which is -the history of the human race, so evolution falls naturally into two -categories,—the evolution of the individual, and the evolution of the -sum of living beings. It will be convenient to deal with the modern -doctrine of evolution under these two heads. - - -I. _The Evolution of the Individual._ - -No exception is, at this time, known to the general law, established -upon an immense multitude of direct observations, that every living -thing is evolved from a particle of matter in which no trace of the -distinctive characters of the adult form of that living thing is -discernible. This particle is termed a _germ_. Harvey[76] says— - - “Omnibus viventibus primordium insit, ex quo et a quo - proveniant. Liceat hoc nobis _primordium vegetale_ - nominare; nempe substantiam quandam corpoream vitam - habentem potentiâ; vel quoddam per se existens, quod - aptum sit, in vegetativam formam, ab interno principio - operante, mutari. Quale nempe primordium, ovum est et - plantarum semen; tale etiam viviparorum conceptus, - et insectorum _vermis_ ab Aristotele dictus: diversa - scilicet diversorum viventium primordia.” - -The definition of a germ as “matter potentially alive, and having -within itself the tendency to assume a definite living form,” appears -to meet all the requirements of modern science. For, notwithstanding it -might be justly questioned whether a germ is not merely potentially, -but rather actually, alive, though its vital manifestations are reduced -to a minimum, the term “potential” may fairly be used in a sense broad -enough to escape the objection. And the qualification of “potential” -has the advantage of reminding us that the great characteristic of -the germ is not so much what it is, but what it may, under suitable -conditions, become. Harvey shared the belief of Aristotle—whose -writings he so often quotes, and of whom he speaks as his precursor and -model, with the generous respect with which one genuine worker should -regard another—that such germs may arise by a process of “equivocal -generation” out of not-living matter; and the aphorism so commonly -ascribed to him, “_omne vivum ex ovo_,” and which is indeed a fair -summary of his reiterated assertions, though incessantly employed -against the modern advocates of spontaneous generation, can be honestly -so used only by those who have never read a score of pages of the -“Exercitationes.” Harvey, in fact, believed as implicitly as Aristotle -did in the equivocal generation of the lower animals. But, while the -course of modern investigation has only brought out into greater -prominence the accuracy of Harvey’s conception of the nature and mode -of development of germs, it has as distinctly tended to disprove the -occurrence of equivocal generation, or abiogenesis, in the present -course of nature. In the immense majority of both plants and animals, -it is certain that the germ is not merely a body in which life is -dormant or potential, but that it is itself simply a detached portion -of the substance of a pre-existing living body; and the evidence has -yet to be adduced which will satisfy any cautious reasoner that “omne -vivum ex vivo” is not as well-established a law of the existing course -of nature as “omne vivum ex ovo.” - -In all instances which have yet been investigated, the substance of -this germ has a peculiar chemical composition, consisting of at fewest -four elementary bodies, viz. carbon, hydrogen, oxygen, and nitrogen, -united into the ill-defined compound known as protein, and associated -with much water, and very generally, if not always, with sulphur and -phosphorus in minute proportions. Moreover, up to the present time, -protein is known only as a product and constituent of living matter. -Again, a true germ is either devoid of any structure discernible by -optical means, or, at most, it is a simple nucleated cell.[77] - -In all cases, the process of evolution consists in a succession of -changes of the form, structure, and functions of the germ, by which -it passes, step by step, from an extreme simplicity, or relative -homogeneity, of visible structure, to a greater or less degree -of complexity or heterogeneity; and the course of progressive -differentiation is usually accompanied by growth, which is effected by -intussusception. This intussusception, however, is a very different -process from that imagined either by Buffon, or by Bonnet. The -substance by the addition of which the germ is enlarged is, in no -case, simply absorbed ready-made from the not-living world and packed -between the elementary constituents of the germ, as Bonnet imagined; -still less does it consist of the “molecules organiques” of Buffon. The -new material is, in great measure, not only absorbed but assimilated, -so that it becomes part and parcel of the molecular structure of -the living body into which it enters. And, so far from the fully -developed organism being simply the germ _plus_ the nutriment which -it has absorbed, it is probable that the adult contains neither in -form, nor in substance, more than an inappreciable fraction of the -constituents of the germ, and that it is almost, if not wholly, made -up of assimilated and metamorphosed nutriment. In the great majority of -cases, at any rate, the full-grown organism becomes what it is by the -absorption of not-living matter, and its conversion into living matter -of a specific type. As Harvey says (Ex. 45), all parts of the body are -nourished “ab eodem succo alibili, aliter aliterque cambiato,” “ut -plantæ omnes ex eodem communi nutrimento (sive rore seu terræ humore).” - -In all animals and plants, above the lowest, the germ is a nucleated -cell, using that term in its broadest sense; and the first step in the -process of the evolution of the individual is the division of this -cell into two or more portions. The process of division is repeated, -until the organism, from being unicellular, becomes multicellular. -The single cell becomes a cell-aggregate; and it is to the growth and -metamorphosis of the cells of the cell-aggregate thus produced, that -all the organs and tissues of the adult owe their origin. - -In certain animals belonging to every one of the chief groups into -which the _Metazoa_ are divisible, the cells of the cell-aggregate -which results from the process of yelk-division, and which is termed -a _morula_, diverge from one another in such a manner as to give rise -to a central space, around which they dispose themselves as a coat or -envelope; and thus the morula becomes a vesicle filled with fluid, -the _planula_. The wall of the planula is next pushed in on one side, -or invaginated, whereby it is converted into a double-walled sac -with an opening, the _blastopore_, which leads into the cavity lined -by the inner wall. This cavity is the primitive alimentary cavity or -_archenteron_; the inner, or invaginated, layer is the _hypoblast_, -the outer the _epiblast_; and the embryo, in this stage, is termed -a _gastrula_. In all the higher animals, a layer of cells makes its -appearance between the hypoblast and the epiblast, and is termed the -_mesoblast_. In the further course of development, the epiblast becomes -the ectoderm or epidermic layer of the body; the hypoblast becomes -the epithelium of the middle portion of the alimentary canal; and the -mesoblast gives rise to all the other tissues, except the central -nervous system, which originates from an ingrowth of the epiblast. - -With more or less modification in detail, the embryo has been observed -to pass through these successive evolutional stages in sundry Sponges, -Cœlenterates, Worms, Echinoderms, Tunicates, Arthropods, Mollusks, -and Vertebrates; and there are valid reasons for the belief, that -all animals of higher organisation than the _Protozoa_ agree in the -general character of the early stages of their individual evolution. -Each, starting from the condition of a simple nucleated cell, becomes -a cell-aggregate; and this passes through a condition which represents -the gastrula stage, before taking on the features distinctive of the -group to which it belongs. Stated in this form, the “gastræa theory” of -Haeckel appears to the present writer to be one of the most important -and best founded of recent generalisations. So far as individual -plants and animals are concerned, therefore, evolution is not a -speculation but a fact; and it takes place by epigenesis. - - “Animal ... per _epigenesin_ procreatur, materiam simul - attrahit, parat, concoquit, et eâdem utitur; formatur - simul et augetur ... primum futuri corporis concrementum - ... prout augetur, dividitur sensim et distinguitur in - partes, non simul omnes, sed alias post alias natas, et - ordine quasque suo emergentes.”[78] - -In these words, by the divination of genius, Harvey, in the seventeenth -century, summed up the outcome of the work of all those who, with -appliances he could not dream of, are continuing his labours in the -nineteenth century. - -Nevertheless, though the doctrine of epigenesis, as understood by -Harvey, has definitively triumphed over the doctrine of evolution, -as understood by his opponents of the eighteenth century, it is not -impossible that, when the analysis of the process of development is -carried still farther, and the origin of the molecular components of -the physically gross, though sensibly minute, bodies which we term -germs is traced, the theory of development will approach more nearly -to metamorphosis than to epigenesis. Harvey thought that impregnation -influenced the female organism as a contagion; and that the blood, -which he conceived to be the first rudiment of the germ, arose in -the clear fluid of the “colliquamentum” of the ovum by a process of -concrescence, as a sort of living precipitate. We now know, on the -contrary, that the female germ or ovum, in all the higher animals -and plants, is a body which possesses the structure of a nucleated -cell; that impregnation consists in the fusion of the substance[79] -of another more or less modified nucleated cell, the male germ, with -the ovum; and that the structural components of the body of the -embryo are all derived, by a process of division, from the coalesced -male and female germs. Hence it is conceivable, and indeed probable, -that every part of the adult contains molecules, derived both from -the male and from the female parent; and that, regarded as a mass -of molecules, the entire organism may be compared to a web of which -the warp is derived from the female and the woof from the male. And -each of these may constitute one individuality, in the same sense -as the whole organism is one individual, although the matter of the -organism has been constantly changing. The primitive male and female -molecules may play the part of Buffon’s “moules organiques,” and -mould the assimilated nutriment, each according to its own type, into -innumerable new molecules. From this point of view the process, which, -in its superficial aspect, is epigenesis, appears in essence, to be -evolution, in the modified sense adopted in Bonnet’s later writings; -and development is merely the expansion of a potential organism or -“original preformation” according to fixed laws. - - -II. _The Evolution of the Sum of Living Beings._ - -The notion that all the kinds of animals and plants may have come into -existence by the growth and modification of primordial germs is as old -as speculative thought; but the modern scientific form of the doctrine -can be traced historically to the influence of several converging lines -of philosophical speculation and of physical observation, none of which -go farther back than the seventeenth century. These are:— - -1. The enunciation by Descartes of the conception that the physical -universe, whether living or not living, is a mechanism, and that, as -such, it is explicable on physical principles. - -2. The observation of the gradations of structure, from extreme -simplicity to very great complexity, presented by living things, and of -the relation of these graduated forms to one another. - -3. The observation of the existence of an analogy between the series -of gradations presented by the species which compose any great group -of animals or plants, and the series of embryonic conditions of the -highest members of that group. - -4. The observation that large groups of species of widely different -habits present the same fundamental plan of structure; and that parts -of the same animal or plant, the functions of which are very different, -likewise exhibit modifications of a common plan. - -5. The observation of the existence of structures, in a rudimentary -and apparently useless condition, in one species of a group, which are -fully developed and have definite functions in other species of the -same group. - -6. The observation of the effects of varying conditions in modifying -living organisms. - -7. The observation of the facts of geographical distribution. - -8. The observation of the facts of the geological succession of the -forms of life. - - -1. Notwithstanding the elaborate disguise which fear of the powers that -were led Descartes to throw over his real opinions, it is impossible to -read the “Principes de la Philosophie” without acquiring the conviction -that this great philosopher held that the physical world and all things -in it, whether living or not living, have originated by a process of -evolution, due to the continuous operation of purely physical causes, -out of a primitive relatively formless matter.[80] - -The following passage is especially instructive:— - - “Et tant s’en faut que je veuille que l’on croie toutes - les choses que j’écrirai, que même je pretends en - proposer ici quelques unes que je crois absolument être - fausses; à savoir, je ne doute point que le monde n’ait - été créé au commencement avec autant de perfection qu’il - en a; en sorte que le soleil, la terre, la lune, et - les étoiles ont été dès lors; et que la terre n’a pas - eu seulement en soi les semences des plantes, mais que - les plantes même en ont couvert une partie; et qu’Adam - et Eve n’ont pas été créés enfans mais en âge d’hommes - parfaits. La religion chrétienne veut que nous le croyons - ainsi, et la raison naturelle nous persuade entièrement - cette vérité; car si nous considérons la toute puissance - de Dieu, nous devons juger que tout ce qu’il a fait a - eu dès le commencement toute la perfection qu’il devoit - avoir. Mais néanmoins, comme on connôitroit beaucoup - mieux quelle a été la nature d’Adam et celle des arbres - de Paradis si on avoit examiné comment les enfants se - forment peu à peu dans le ventre de leurs mères et - comment les plantes sortent de leurs semences, que si on - avoit seulement considéré quels ils ont été quand Dieu - les a créés: tout de même, nous ferons mieux entendre - quelle est généralement la nature de toutes les choses - qui sont au monde si nous pouvons imaginer quelques - principes qui soient fort intelligibles et fort simples, - desquels nous puissions voir clairement que les astres et - la terre et enfin tout ce monde visible auroit pu être - produit ainsi que de quelques semences (bien que nous - sachions qu’il n’a pas été produit en cette façon) que si - nous la decrivions seulement comme il est, ou bien comme - nous croyons qu’il a été créé. Et parceque je pense avoir - trouvé des principes qui sont tels, je tacherai ici de - les expliquer.”[81] - -If we read between the lines of this singular exhibition of force of -one kind and weakness of another, it is clear that Descartes believed -that he had divined the mode in which the physical universe had been -evolved; and the “Traité de l’homme,” and the essay “Sur les Passions” -afford abundant additional evidence that he sought for, and thought -he had found, an explanation of the phenomena of physical life by -deduction from purely physical laws. - -Spinoza abounds in the same sense, and is as usual perfectly candid— - - “Naturæ leges et regulæ, secundum quas omnia fiunt et - ex unis formis in alias mutantur, sunt ubique et semper - eadem.”[82] - -Leibnitz’s doctrine of continuity necessarily led him in the same -direction; and, of the infinite multitude of monads with which he -peopled the world, each is supposed to be the focus of an endless -process of evolution and involution. In the “Protogæa,” xxvi., Leibnitz -distinctly suggests the mutability of species— - - “Alii mirantur in saxis passim species videri quas vel - in orbe cognito, vel saltem in vicinis locis frustra - quæras. Ita “Cornua Ammonis,” quæ ex nautilorum numero - habeantur, passim et forma et magnitudine (nam et pedali - diametro aliquando reperiuntur) ab omnibus illis naturis - discrepare dicunt, quas præbet mare. Sed quis absconditos - ejus recessus aut subterraneas abyssos pervestigavit? - quam multa nobis animalia antea ignota offert novus - orbis? Et credibile est per magnas illas conversiones - etiam animalium species plurimum immutatas.” - -Thus, in the end of the seventeenth century, the seed was sown which -has, at intervals, brought forth recurrent crops of evolutional -hypotheses, based, more or less completely, on general reasonings. - -Among the earliest of these speculations is that put forward by Benoit -de Maillet in his “Telliamed,” which, though printed in 1735, was -not published until twenty-three years later. Considering that this -book was written before the time of Haller, or Bonnet, or Linnæus, -or Hutton, it surely deserves more respectful consideration than it -usually receives. For De Maillet not only has a definite conception -of the plasticity of living things, and of the production of existing -species by the modification of their predecessors; but he clearly -apprehends the cardinal maxim of modern geological science, that the -explanation of the structure of the globe is to be sought in the -deductive application to geological phenomena of the principles -established inductively by the study of the present course of nature. -Somewhat later, Maupertuis[83] suggested a curious hypothesis as to -the causes of variation, which he thinks may be sufficient to account -for the origin of all animals from a single pair. Robinet[84] followed -out much the same line of thought as De Maillet, but less soberly; and -Bonnet’s speculations in the “Palingénésie,” which appeared in 1769, -have already been mentioned. Buffon (1753-1778), at first a partisan -of the absolute immutability of species, subsequently appears to have -believed that larger or smaller groups of species have been produced by -the modification of a primitive stock; but he contributed nothing to -the general doctrine of evolution. - -Erasmus Darwin (“Zoonomia,” 1794), though a zealous evolutionist, can -hardly be said to have made any real advance on his predecessors; -and, notwithstanding that Goethe (1791-4) had the advantage of a -wide knowledge of morphological facts, and a true insight into their -signification, while he threw all the power of a great poet into -the expression of his conceptions, it may be questioned whether he -supplied the doctrine of evolution with a firmer scientific basis -than it already possessed. Moreover, whatever the value of Goethe’s -labours in that field, they were not published before 1820, long after -evolutionism had taken a new departure from the works of Treviranus -and Lamarck—the first of its advocates who were equipped for their -task with the needful large and accurate knowledge of the phenomena of -life, as a whole. It is remarkable that each of these writers seems -to have been led, independently and contemporaneously, to invent the -same name of “Biology” for the science of the phenomena of life; and -thus, following Buffon, to have recognised the essential unity of these -phenomena, and their contradistinction from those of inanimate nature. -And it is hard to say whether Lamarck or Treviranus has the priority in -propounding the main thesis of the doctrine of evolution; for though -the first volume of Treviranus’s “Biologie” appeared only in 1802, he -says, in the preface to his later work, the “Erscheinungen und Gesetze -des organischen Lebens,” dated 1831, that he wrote the first volume of -the “Biologie” “nearly five-and-thirty years ago,” or about 1796. - -Now, in 1794, there is evidence that Lamarck held doctrines which -present a striking contrast to those which are to be found in the -“Philosophic Zoologique,” as the following passages show:— - - “685. Quoique mon unique objet dans cet article n’ait été - que de traiter de la cause physique de l’entretien de la - vie des êtres organiques, malgré cela j’ai osé avancer - en débutant, que l’existence de ces êtres étonnants - n’appartiennent nullement à la nature; que tout ce qu’on - peut entendre par le mot _nature_, ne pouvoit donner la - vie, c’est-à-dire, que toutes les qualités de la matière, - jointes à toutes les circonstances possibles, et même à - l’activité répandue dans l’univers, ne pouvaient point - produire un être muni du mouvement organique, capable de - reproduire son semblable, et sujet à la mort. - - “686. Tous les individus de cette nature, qui existent, - proviennent d’individus semblables qui tous ensemble - constituent l’espèce entière. Or, je crois qu’il est - aussi impossible à l’homme de connôitre la cause physique - du premier individu de chaque espèce, que d’assigner - aussi physiquement la cause de l’existence de la - matière ou de l’univers entier. C’est au moins ce que - le résultat de mes connaissances et de mes réflexions - me portent à penser. S’il existe beaucoup de variétés - produites par l’effet des circonstances, ces variétés ne - dénaturent point les espèces; mais on se trompe, sans - doute souvent, en indiquant comme espèce, ce qui n’est - que variété; et alors je sens que cette erreur peut tirer - à conséquence dans les raisonnements que l’on fait sur - cette matière.”[85] - -The first three volumes of Treviranus’s “Biologie,” which contain -his general views of evolution, appeared between 1802 and 1805. The -“Recherches sur l’organisation des corps vivants,” in which the -outlines of Lamarck’s doctrines are given, was published in 1802; but -the full development of his views, in the “Philosophie Zoologique,” did -not take place until 1809. - -The “Biologie” and the “Philosophie Zoologique” are both very -remarkable productions, and are still worthy of attentive study, but -they fell upon evil times. The vast authority of Cuvier was employed -in support of the traditionally respectable hypotheses of special -creation and of catastrophism; and the wild speculations of the -“Discours sur les Révolutions de la Surface du Globe” were held to be -models of sound scientific thinking, while the really much more sober -and philosophical hypotheses of the “Hydrogeologie” were scouted. For -many years it was the fashion to speak of Lamarck with ridicule, while -Treviranus was altogether ignored. - -Nevertheless, the work had been done. The conception of evolution -was henceforward irrepressible, and it incessantly reappears, in one -shape or another,[86] up to the year 1858, when Mr. Darwin and Mr. -Wallace published their “Theory of Natural Selection.” The “Origin of -Species” appeared in 1859; and it is within the knowledge of all whose -memories go back to that time, that, henceforward, the doctrine of -evolution has assumed a position and acquired an importance which it -never before possessed. In the “Origin of Species,” and in his other -numerous and important contributions to the solution of the problem of -biological evolution, Mr. Darwin confines himself to the discussion of -the causes which have brought about the present condition of living -matter, assuming such matter to have once come into existence. On the -other hand, Mr. Spencer[87] and Professor Haeckel[88] have dealt with -the whole problem of evolution. The profound and vigorous writings of -Mr. Spencer embody the spirit of Descartes in the knowledge of our own -day, and may be regarded as the “Principes de la Philosophie” of the -nineteenth century; while, whatever hesitation may not unfrequently -be felt by less daring minds, in following Haeckel in many of his -speculations, his attempt to systematise the doctrine of evolution and -to exhibit its influence as the central thought of modern biology, -cannot fail to have a far-reaching influence on the progress of science. - -If we seek for the reason of the difference between the scientific -position of the doctrine of evolution a century ago, and that which it -occupies now, we shall find it in the great accumulation of facts, the -several classes of which have been enumerated above, under the second -to the eighth heads. For those which are grouped under the second to -the seventh of these classes, respectively, have a clear significance -on the hypothesis of evolution, while they are unintelligible if that -hypothesis be denied. And those of the eighth group are not only -unintelligible without the assumption of evolution, but can be proved -never to be discordant with that hypothesis, while, in some cases, -they are exactly such as the hypothesis requires. The demonstration of -these assertions would require a volume, but the general nature of the -evidence on which they rest may be briefly indicated. - -2. The accurate investigation of the lowest forms of animal life, -commenced by Leeuwenhoek and Swammerdam, and continued by the -remarkable labours of Reaumur, Trembley, Bonnet, and a host of other -observers, in the latter part of the seventeenth and the first half -of the eighteenth centuries, drew the attention of biologists to the -gradation in the complexity of organisation which is presented by -living beings, and culminated in the doctrine of the “échelle des -êtres,” so powerfully and clearly stated by Bonnet; and, before him, -adumbrated by Locke and by Leibnitz. In the then state of knowledge, it -appeared that all the species of animals and plants could be arranged -in one series; in such a manner that, by insensible gradations, the -mineral passed into the plant, the plant into the polype, the polype -into the worm, and so, through gradually higher forms of life, to man, -at the summit of the animated world. - -But, as knowledge advanced, this conception ceased to be tenable in -the crude form in which it was first put forward. Taking into account -existing animals and plants alone, it became obvious that they fell -into groups which were more or less sharply separated from one another; -and, moreover, that even the species of a genus can hardly ever be -arranged in linear series. Their natural resemblances and differences -are only to be expressed by disposing them as if they were branches -springing from a common hypothetical centre. - -Lamarck, while affirming the verbal proposition that animals form a -single series, was forced by his vast acquaintance with the details -of zoology to limit the assertion to such a series as may be formed -out of the abstractions constituted by the common characters of each -group.[89] - -Cuvier on anatomical, and Von Baer on embryological grounds, made the -further step of proving that, even in this limited sense, animals -cannot be arranged in a single series, but that there are several -distinct plans of organisation to be observed among them, no one of -which, in its highest and most complicated modification, leads to any -of the others. - -The conclusions enunciated by Cuvier and Von Baer have been confirmed, -in principle, by all subsequent research into the structure of animals -and plants. But the effect of the adoption of these conclusions has -been rather to substitute a new metaphor for that of Bonnet than to -abolish the conception expressed by it. Instead of regarding living -things as capable of arrangement in one series like the steps of a -ladder, the results of modern investigation compel us to dispose them -as if they were the twigs and branches of a tree. The ends of the twigs -represent individuals, the smallest groups of twigs species, larger -groups genera, and so on, until we arrive at the source of all these -ramifications of the main branch, which is represented by a common -plan of structure. At the present moment, it is impossible to draw up -any definition, based on broad anatomical or developmental characters, -by which any one of Cuvier’s great groups shall be separated from all -the rest. On the contrary, the lower members of each tend to converge -towards the lower members of all the others. The same may be said of -the vegetable world. The apparently clear distinction between flowering -and flowerless plants has been broken down by the series of gradations -between the two exhibited by the _Lycopodiaceæ_, _Rhizocarpeæ_, and -_Gymnospermeæ_. The groups of _Fungi_, _Lichenes_, and _Algæ_ have -completely run into one another, and, when the lowest forms of each are -alone considered, even the animal and vegetable kingdoms cease to have -a definite frontier. - -If it is permissible to speak of the relations of living forms to one -another metaphorically, the similitude chosen must undoubtedly be -that of a common root, whence two main trunks, one representing the -vegetable and one the animal world, spring; and, each dividing into a -few main branches, these subdivide into multitudes of branchlets and -these into smaller groups of twigs. - -As Lamarck has well said—[90] - - “Il n’y a que ceux qui se sont longtemps et fortement - occupés de la détermination des espèces, et qui ont - consulté de riches collections, qui peuvent savoir - jusqu’à quel point les _espèces_, parmi les corps vivants - se fondent les unes dans les autres, et qui ont pu se - convaincre que, dans les parties où nous voyons des - _espèces_ isolès, cela n’est ainsi que parcequ’il nous - en manque d’autres qui en sont plus voisines et que nous - n’avons pas encore recueillies. - - “Je ne veux pas dire pour cela que les animaux qui - existent forment une série très-simple et partout - également nuancée; mais je dis qu’ils forment une série - rameuse, irréguliérement graduée et qui n’a point de - discontinuité dans ses parties, ou qui, du moins, n’en - a toujours pas eu, s’il est vrai que, par suite de - quelques espèces perdues, il s’en trouve quelque part. - Il en resulte que les _espèces_ qui terminent chaque - rameau de la série générale tiennent, au moins d’un - côté, à d’autres espèces voisines qui se nuancent avec - elles. Voilà ce que l’état bien connu des choses me - met maintenant à portée de demontrer. Je n’ai besoin - d’aucune hypothèse ni d’aucune supposition pour cela: - j’en atteste tous les naturalistes observateurs.” - -3. In a remarkable essay[91] Meckel remarks— - - “There is no good physiologist who has not been struck by - the observation that the original form of all organisms - is one and the same, and that out of this one form, all, - the lowest as well as the highest, are developed in such - a manner that the latter pass through the permanent forms - of the former as transitory stages. Aristotle, Haller, - Harvey, Kielmeyer, Autenrieth, and many others, have - either made this observation incidentally, or, especially - the latter, have drawn particular attention to it, and - drawn therefrom results of permanent importance for - physiology.” - -Meckel proceeds to exemplify the thesis, that the lower forms of -animals represent stages in the course of the development of the -higher, with a large series of illustrations. - -After comparing the Salamanders and the perenni-branchiate _Urodela_ -with the Tadpoles and the Frogs, and enunciating the law that the more -highly any animal is organised the more quickly does it pass through -the lower stages, Meckel goes on to say— - - “From these lowest Vertebrata to the highest, and to - the highest forms among these, the comparison between - the embryonic conditions of the higher animals and the - adult states of the lower can be more completely and - thoroughly instituted than if the survey is extended to - the Invertebrata, inasmuch as the latter are in many - respects constructed upon an altogether too dissimilar - type; indeed they often differ from one another far more - than the lowest vertebrate does from the highest mammal; - yet the following pages will show that the comparison - may also be extended to them with interest. In fact, - there is a period when, as Aristotle long ago said, the - embryo of the highest animal has the form of a mere worm; - and, devoid of internal and external organisation, is - merely an almost structureless lump of polype-substance. - Notwithstanding the origin of organs, it still for a - certain time, by reason of its want of an internal bony - skeleton, remains worm and mollusk, and only later enters - into the series of the Vertebrata, although traces of the - vertebral column even in the earliest periods testify its - claim to a place in that series.”—_Op. cit._ pp. 4, 5. - -If Meckel’s proposition is so far qualified, that the comparison of -adult with embryonic forms is restricted within the limits of one type -of organisation; and, if it is further recollected that the resemblance -between the permanent lower form and the embryonic stage of a higher -form is not special but general, it is in entire accordance with modern -embryology; although there is no branch of biology which has grown so -largely, and improved its methods so much, since Meckel’s time, as -this. In its original form, the doctrine of “arrest of development,” -as advocated by Geoffroy Saint-Hilaire and Serres, was no doubt an -over-statement of the case. It is not true, for example, that a fish -is a reptile arrested in its development, or that a reptile was ever -a fish: but it is true that the reptile embryo, at one stage of its -development, is an organism which, if it had an independent existence, -must be classified among fishes; and all the organs of the reptile -pass, in the course of their development, through conditions which are -closely analogous to those which are permanent in some fishes. - -4. That branch of biology which is termed Morphology is a commentary -upon, and expansion of, the proposition that widely different animals -or plants, and widely different parts of animals or plants, are -constructed upon the same plan. From the rough comparison of the -skeleton of a bird with that of a man by Belon, in the sixteenth -century (to go no farther back), down to the theory of the limbs -and the theory of the skull at the present day; or, from the first -demonstration of the homologies of the parts of a flower by C. F. -Wolff, to the present elaborate analysis of the floral organs, -morphology exhibits a continual advance towards the demonstration of a -fundamental unity among the seeming diversities of living structures. -And this demonstration has been completed by the final establishment -of the cell theory, which involves the admission of a primitive -conformity, not only of all the elementary structures in animals and -plants respectively, but of those in the one of these great divisions -of living things with those in the other. No _à priori_ difficulty can -be said to stand in the way of evolution, when it can be shown that -all animals and all plants proceed by modes of development, which are -similar in principle, from a fundamental protoplasmic material. - -5. The innumerable cases of structures, which are rudimentary and -apparently useless, in species, the close allies of which possess -well developed and functionally important homologous structures, are -readily intelligible on the theory of evolution, while it is hard to -conceive their _raison d’être_ on any other hypothesis. However, a -cautious reasoner will probably rather explain such cases deductively -from the doctrine of evolution than endeavour to support the doctrine -of evolution by them. For it is almost impossible to prove that any -structure, however rudimentary, is useless—that is to say, that it -plays no part whatever in the economy; and, if it is in the slightest -degree useful, there is no reason why, on the hypothesis of direct -creation, it should not have been created. Nevertheless, double-edged -as is the argument from rudimentary organs, there is probably none -which has produced a greater effect in promoting the general acceptance -of the theory of evolution. - -6. The older advocates of evolution sought for the causes of the -process exclusively in the influence of varying conditions, such -as climate and station, or hybridisation, upon living forms. Even -Treviranus has got no farther than this point. Lamarck introduced -the conception of the action of an animal on itself as a factor in -producing modification. Starting from the well-known fact that the -habitual use of a limb tends to develop the muscles of the limb, and to -produce a greater and greater facility in using it, he made the general -assumption that the effort of an animal to exert an organ in a given -direction tends to develop the organ in that direction. But a little -consideration showed that, though Lamarck had seized what, as far as -it goes, is a true cause of modification, it is a cause the actual -effects of which are wholly inadequate to account for any considerable -modification in animals, and which can have no influence at all in the -vegetable world; and probably nothing contributed so much to discredit -evolution, in the early part of this century, as the floods of easy -ridicule which were poured upon this part of Lamarck’s speculation. -The theory of natural selection, or survival of the fittest, was -suggested by Wells in 1813, and further elaborated by Matthew in 1831. -But the pregnant suggestions of these writers remained practically -unnoticed and forgotten, until the theory was independently devised -and promulgated by Darwin and Wallace in 1858, and the effect of its -publication was immediate and profound. - -Those who were unwilling to accept evolution, without better grounds -than such as are offered by Lamarck, or the author of that particularly -unsatisfactory book, the “Vestiges of the Natural History of the -Creation,” and who therefore preferred to suspend their judgment on the -question, found, in the principle of selective breeding, pursued in all -its applications with marvellous knowledge and skill by Mr. Darwin, -a valid explanation of the occurrence of varieties and races; and -they saw clearly that, if the explanation would apply to species, it -would not only solve the problem of their evolution, but that it would -account for the facts of teleology, as well as for those of morphology; -and for the persistence of some forms of life unchanged through long -epochs of time, while others undergo comparatively rapid metamorphosis. - -How far “natural selection” suffices for the production of species -remains to be seen. Few can doubt that, if not the whole cause, it is a -very important factor in that operation; and that it must play a great -part in the sorting out of varieties into those which are transitory -and those which are permanent. - -But the causes and conditions of variation have yet to be thoroughly -explored; and the importance of natural selection will not be impaired, -even if further inquiries should prove that variability is definite, -and is determined in certain directions rather than in others, by -conditions inherent in that which varies. It is quite conceivable that -every species tends to produce varieties of a limited number and kind, -and that the effect of natural selection is to favour the development -of some of these, while it opposes the development of others along -their predetermined lines of modification. - -7. No truths brought to light by biological investigation were better -calculated to inspire distrust of the dogmas intruded upon science -in the name of theology, than those which relate to the distribution -of animals and plants on the surface of the earth. Very skilful -accommodation was needful, if the limitation of sloths to South -America, and of the ornithorhynchus to Australia, was to be reconciled -with the literal interpretation of the history of the deluge; and, -with the establishment of the existence of distinct provinces of -distribution, any serious belief in the peopling of the world by -migration from Mount Ararat came to an end. - -Under these circumstances, only one alternative was left for those -who denied the occurrence of evolution—namely, the supposition that -the characteristic animals and plants of each great province were -created, as such, within the limits in which we find them. And as the -hypothesis of “specific centres,” thus formulated, was heterodox from -the theological point of view, and unintelligible under its scientific -aspect, it may be passed over without further notice, as a phase of -transition from the creational to the evolutional hypothesis. - -8. In fact, the strongest and most conclusive arguments in favour of -evolution are those which are based upon the facts of geographical, -taken in conjunction with those of geological, distribution. - -Both Mr. Darwin and Mr. Wallace lay great stress on the close relation -which obtains between the existing fauna of any region and that of -the immediately antecedent geological epoch in the same region; and -rightly, for it is in truth inconceivable that there should be no -genetic connection between the two. It is possible to put into words -the proposition that all the animals and plants of each geological -epoch were annihilated, and that a new set of very similar forms was -created for the next epoch; but it may be doubted if any one who ever -tried to form a distinct mental image of this process of spontaneous -generation on the grandest scale, ever really succeeded in realising it. - -Within the last twenty years, the attention of the best palæontologists -has been withdrawn from the hodman’s work of making “new species” -of fossils, to the scientific task of completing our knowledge of -individual species, and tracing out the succession of the forms -presented by any given type in time. - -Those who desire to inform themselves of the nature and extent of -the evidence bearing on these questions may consult the works of -Rütimeyer, Gaudry, Kowalewsky, Marsh, and the writer of the present -article. It must suffice, in this place, to say that the successive -forms of the Equine type have been fully worked out; while those of -nearly all the other existing types of Ungulate mammals and of the -_Carnivora_ have been almost as closely followed through the Tertiary -deposits; the gradations between birds and reptiles have been traced; -and the modifications undergone by the _Crocodilia_, from the Triassic -epoch to the present day, have been demonstrated. On the evidence of -palæontology, the evolution of many existing forms of animal life -from their predecessors is no longer an hypothesis, but an historical -fact; it is only the nature of the physiological factors to which that -evolution is due which is still open to discussion. - - - - -XII. - -THE COMING OF AGE OF “THE ORIGIN OF SPECIES.” - - -Many of you will be familiar with the aspect of this small -green-covered book. It is a copy of the first edition of the “Origin of -Species,” and bears the date of its production—the 1st of October 1859. -Only a few months, therefore, are needed to complete the full tale of -twenty-one years since its birthday. - -Those whose memories carry them back to this time will remember that -the infant was remarkably lively, and that a great number of excellent -persons mistook its manifestations of a vigorous individuality for -mere naughtiness; in fact there was a very pretty turmoil about its -cradle. My recollections of the period are particularly vivid; for, -having conceived a tender affection for a child of what appeared to me -to be such remarkable promise, I acted for some time in the capacity -of a sort of under-nurse, and thus came in for my share of the storms -which threatened the very life of the young creature. For some years it -was undoubtedly warm work; but considering how exceedingly unpleasant -the apparition of the new-comer must have been to those who did not -fall in love with him at first sight, I think it is to the credit of -our age that the war was not fiercer, and that the more bitter and -unscrupulous forms of opposition died away as soon as they did. - -I speak of this period as of something past and gone, possessing -merely an historical, I had almost said an antiquarian interest. For, -during the second decade of the existence of the “Origin of Species,” -opposition, though by no means dead, assumed a different aspect. On the -part of all those who had any reason to respect themselves, it assumed -a thoroughly respectful character. By this time, the dullest began to -perceive that the child was not likely to perish of any congenital -weakness or infantile disorder, but was growing into a stalwart -personage, upon whom mere goody scoldings and threatenings with the -birch-rod were quite thrown away. - -In fact, those who have watched the progress of science within the last -ten years will bear me out to the full, when I assert that there is no -field of biological inquiry in which the influence of the “Origin of -Species” is not traceable; the foremost men of science in every country -are either avowed champions of its leading doctrines, or at any rate -abstain from opposing them; a host of young and ardent investigators -seek for and find inspiration and guidance in Mr. Darwin’s great work; -and the general doctrine of evolution, to one side of which it gives -expression, obtains, in the phenomena of biology, a firm base of -operations whence it may conduct its conquest of the whole realm of -nature. - -History warns us, however, that it is the customary fate of new truths -to begin as heresies and to end as superstitions; and, as matters now -stand, it is hardly rash to anticipate that, in another twenty years, -the new generation, educated under the influences of the present day, -will be in danger of accepting the main doctrines of the “Origin of -Species,” with as little reflection, and it may be with as little -justification, as so many of our contemporaries, twenty years ago, -rejected them. - -Against any such a consummation let us all devoutly pray; for the -scientific spirit is of more value than its products, and irrationally -held truths may be more harmful than reasoned errors. Now the essence -of the scientific spirit is criticism. It tells us that whenever a -doctrine claims our assent we should reply, Take it if you can compel -it. The struggle for existence holds as much in the intellectual as in -the physical world. A theory is a species of thinking, and its right -to exist is coextensive with its power of resisting extinction by its -rivals. - -From this point of view, it appears to me that it would be but a poor -way of celebrating the Coming of Age of the “Origin of Species,” were I -merely to dwell upon the facts, undoubted and remarkable as they are, -of its far-reaching influence and of the great following of ardent -disciples who are occupied in spreading and developing its doctrines. -Mere insanities and inanities have before now swollen to portentous -size in the course of twenty years. Let us rather ask this prodigious -change in opinion to justify itself; let us inquire whether anything -has happened since 1859, which will explain, on rational grounds, why -so many are worshipping that which they burned, and burning that which -they worshipped. It is only in this way that we shall acquire the means -of judging whether the movement we have witnessed is a mere eddy of -fashion, or truly one with the irreversible current of intellectual -progress, and, like it, safe from retrogressive reaction. - -Every belief is the product of two factors: the first is the state of -the mind to which the evidence in favour of that belief is presented; -and the second is the logical cogency of the evidence itself. In both -these respects, the history of biological science during the last -twenty years appears to me to afford an ample explanation of the change -which has taken place; and a brief consideration of the salient events -of that history will enable us to understand why, if the “Origin of -Species” appeared now, it would meet with a very different reception -from that which greeted it in 1859. - -One-and-twenty years ago, in spite of the work commenced by Hutton and -continued with rare skill and patience by Lyell, the dominant view -of the past history of the earth was catastrophic. Great and sudden -physical revolutions, wholesale creations and extinctions of living -beings, were the ordinary machinery of the geological epic brought into -fashion by the misapplied genius of Cuvier. It was gravely maintained -and taught that the end of every geological epoch was signalised by a -cataclysm, by which every living being on the globe was swept away, -to be replaced by a brand-new creation when the world returned to -quiescence. A scheme of nature which appeared to be modelled on the -likeness of a succession of rubbers of whist, at the end of each of -which the players upset the table and called for a new pack, did not -seem to shock anybody. - -I may be wrong, but I doubt if, at the present time, there is a single -responsible representative of these opinions left. The progress -of scientific geology has elevated the fundamental principle of -uniformitarianism, that the explanation of the past is to be sought -in the study of the present, into the position of an axiom; and the -wild speculations of the catastrophists, to which we all listened with -respect a quarter of a century ago, would hardly find a single patient -hearer at the present day. No physical geologist now dreams of seeking, -outside the range of known natural causes, for the explanation of -anything that happened millions of years ago, any more than he would be -guilty of the like absurdity in regard to current events. - -The effect of this change of opinion upon biological speculation -is obvious. For, if there have been no periodical general physical -catastrophes, what brought about the assumed general extinctions -and re-creations of life which are the corresponding biological -catastrophes? And, if no such interruptions of the ordinary course of -nature have taken place in the organic, any more than in the inorganic, -world, what alternative is there to the admission of evolution? - -The doctrine of evolution in biology is the necessary result of the -logical application of the principles of uniformitarianism to the -phenomena of life. Darwin is the natural successor of Hutton and Lyell, -and the “Origin of Species” the logical sequence of the “Principles of -Geology.” - -The fundamental doctrine of the “Origin of Species,” as of all forms of -the theory of evolution applied to biology, is “that the innumerable -species, genera, and families of organic beings with which the world -is peopled have all descended, each within its own class or group, -from common parents, and have all been modified in the course of -descent.”[92] - -And, in view of the facts of geology, it follows that all living -animals and plants “are the lineal descendants of those which lived -long before the Silurian epoch.”[93] - -It is an obvious consequence of this theory of descent with -modification, as it is sometimes called, that all plants and animals, -however different they may now be, must, at one time or other, have -been connected by direct or indirect intermediate gradations, and that -the appearance of isolation presented by various groups of organic -beings must be unreal. - -No part of Mr. Darwin’s work ran more directly counter to the -prepossessions of naturalists twenty years ago than this. And such -prepossessions were very excusable, for there was undoubtedly a great -deal to be said, at that time, in favour of the fixity of species -and of the existence of great breaks, which there was no obvious or -probable means of filling up, between various groups of organic beings. - -For various reasons, scientific and unscientific, much had been made of -the hiatus between man and the rest of the higher mammalia, and it is -no wonder that issue was first joined on this part of the controversy. -I have no wish to revive past and happily forgotten controversies; but -I must state the simple fact that the distinctions in the cerebral and -other characters, which were so hotly affirmed to separate man from all -other animals in 1860, have all been demonstrated to be non-existent, -and that the contrary doctrine is now universally accepted and taught. - -But there were other cases in which the wide structural gaps asserted -to exist between one group of animals and another, were by no means -fictitious; and, when such structural breaks were real, Mr. Darwin -could account for them only by supposing that the intermediate forms -which once existed had become extinct. In a remarkable passage he says— - -“We may thus account even for the distinctness of whole classes from -each other—for instance, of birds from all other vertebrate animals—by -the belief that many animal forms of life have been utterly lost, -through which the early progenitors of birds were formerly connected -with the early progenitors of the other vertebrate classes.”[94] - -Adverse criticism made merry over such suggestions as these. Of course -it was easy to get out of the difficulty by supposing extinction; but -where was the slightest evidence that such intermediate forms between -birds and reptiles as the hypothesis required ever existed? And then -probably followed a tirade upon this terrible forsaking of the paths of -“Baconian induction.” - -But the progress of knowledge has justified Mr. Darwin to an extent -which could hardly have been anticipated. In 1862, the specimen of -_Archæopteryx_, which, until the last two or three years, has remained -unique, was discovered; and it is an animal which, in its feathers and -the greater part of its organisation, is a veritable bird, while, in -other parts, it is as distinctly reptilian. - -In 1868, I had the honour of bringing under your notice, in this -theatre, the results of investigations made, up to that time, into -the anatomical characters of certain ancient reptiles, which showed -the nature of the modifications in virtue of which the type of the -quadrupedal reptile passed into that of a bipedal bird; and abundant -confirmatory evidence of the justice of the conclusions which I then -laid before you has since come to light. - -In 1875, the discovery of the toothed birds of the cretaceous -formation in North America by Professor Marsh completed the series of -transitional forms between birds and reptiles, and removed Mr. Darwin’s -proposition that “many animal forms of life have been utterly lost, -through which the early progenitors of birds were formerly connected -with the early progenitors of the other vertebrate classes,” from the -region of hypothesis to that of demonstrable fact. - -In 1859, there appeared to be a very sharp and clear hiatus between -vertebrated and invertebrated animals, not only in their structure, -but, what was more important, in their development. I do not think -that we even yet know the precise links of connection between the two; -but the investigations of Kowalewsky and others upon the development -of _Amphioxus_ and of the _Tunicata_ prove, beyond a doubt, that the -differences which were supposed to constitute a barrier between the two -are non-existent. There is no longer any difficulty in understanding -how the vertebrate type may have arisen from the invertebrate, though -the full proof of the manner in which the transition was actually -effected may still be lacking. - -Again, in 1859, there appeared to be a no less sharp separation -between the two great groups of flowering and flowerless plants. It -is only subsequently that the series of remarkable investigations -inaugurated by Hofmeister has brought to light the extraordinary and -altogether unexpected modifications of the reproductive apparatus in -the _Lycopodiaceæ_, the _Rhizocarpeæ_, and the _Gymnospermeæ_, by which -the ferns and the mosses are gradually connected with the Phanerogamic -division of the vegetable world. - -So, again, it is only since 1859 that we have acquired that wealth of -knowledge of the lowest forms of life which demonstrates the futility -of any attempt to separate the lowest plants from the lowest animals, -and shows that the two kingdoms of living nature have a common -borderland which belongs to both or to neither. - -Thus it will be observed that the whole tendency of biological -investigation, since 1859, has been in the direction of removing the -difficulties which the apparent breaks in the series created at that -time; and the recognition of gradation is the first step towards the -acceptance of evolution. - -As another great factor in bringing about the change of opinion which -has taken place among naturalists, I count the astonishing progress -which has been made in the study of embryology. Twenty years ago, -not only were we devoid of any accurate knowledge of the mode of -development of many groups of animals and plants, but the methods of -investigation were rude and imperfect. At the present time, there is -no important group of organic beings the development of which has -not been carefully studied; and the modern methods of hardening and -section-making enable the embryologist to determine the nature of the -process, in each case, with a degree of minuteness and accuracy which -is truly astonishing to those whose memories carry them back to the -beginnings of modern histology. And the results of these embryological -investigations are in complete harmony with the requirements of the -doctrine of evolution. The first beginnings of all the higher forms of -animal life are similar, and however diverse their adult conditions, -they start from a common foundation. Moreover, the process of -development of the animal or the plant from its primary egg or germ is -a true process of evolution—a progress from almost formless to more or -less highly organised matter, in virtue of the properties inherent in -that matter. - -To those who are familiar with the process of development, all _à -priori_ objections to the doctrine of biological evolution appear -childish. Any one who has watched the gradual formation of a -complicated animal from the protoplasmic mass, which constitutes the -essential element of a frog’s or a hen’s egg, has had under his eyes -sufficient evidence that a similar evolution of the whole animal world -from the like foundation is, at any rate, possible. - -Yet another product of investigation has largely contributed to the -removal of the objections to the doctrine of evolution current in 1859. -It is the proof afforded by successive discoveries that Mr. Darwin -did not over-estimate the imperfection of the geological record. No -more striking illustration of this is needed than a comparison of our -knowledge of the mammalian fauna of the Tertiary epoch in 1859 with its -present condition. M. Gaudry’s researches on the fossils of Pikermi -were published in 1868, those of Messrs. Leidy, Marsh, and Cope, on -the fossils of the Western Territories of America, have appeared -almost wholly since 1870, those of M. Filhol on the phosphorites of -Quercy in 1878. The general effect of these investigations has been -to introduce to us a multitude of extinct animals, the existence of -which was previously hardly suspected; just as if zoologists were to -become acquainted with a country, hitherto unknown, as rich in novel -forms of life as Brazil or South Africa once were to Europeans. Indeed, -the fossil fauna of the Western Territories of America bids fair to -exceed in interest and importance all other known Tertiary deposits -put together; and yet, with the exception of the case of the American -tertiaries, these investigations have extended over very limited areas; -and, at Pikermi, were confined to an extremely small space. - - -Such appear to me to be the chief events in the history of the progress -of knowledge during the last twenty years, which account for the -changed feeling with which the doctrine of evolution is at present -regarded by those who have followed the advance of biological science, -in respect of those problems which bear indirectly upon that doctrine. - -But all this remains mere secondary evidence. It may remove dissent, -but it does not compel assent. Primary and direct evidence in favour of -evolution can be furnished only by palæontology. The geological record, -so soon as it approaches completeness, must, when properly questioned, -yield either an affirmative or a negative answer: if evolution has -taken place, there will its mark be left; if it has not taken place, -there will lie its refutation. - -What was the state of matters in 1859? Let us hear Mr. Darwin, who may -be trusted always to state the case against himself as strongly as -possible. - -“On this doctrine of the extermination of an infinitude of connecting -links between the living and extinct inhabitants of the world, and at -each successive period between the extinct and still older species, -why is not every geological formation charged with such links? Why -does not every collection of fossil remains afford plain evidence -of the gradation and mutation of the forms of life? We meet with no -such evidence, and this is the most obvious and plausible of the many -objections which may be urged against my theory.”[95] - -Nothing could have been more useful to the opposition than this -characteristically candid avowal, twisted as it immediately was into -an admission that the writer’s views were contradicted by the facts of -palæontology. But, in fact, Mr. Darwin made no such admission. What he -says in effect is, not that palæontological evidence is against him, -but that it is not distinctly in his favour; and, without attempting -to attenuate the fact, he accounts for it by the scantiness and the -imperfection of that evidence. - -What is the state of the case now, when, as we have seen, the amount -of our knowledge respecting the mammalia of the Tertiary epoch -is increased fifty-fold, and in some directions even approaches -completeness? - -Simply this, that, if the doctrine of evolution had not existed, -palæontologists must have invented it, so irresistibly is it forced -upon the mind by the study of the remains of the Tertiary mammalia -which have been brought to light since 1859. - -Among the fossils of Pikermi, Gaudry found the successive stages -by which the ancient civets passed into the more modern hyænas; -through the Tertiary deposits of Western America, Marsh tracked the -successive forms by which the ancient stock of the horse has passed -into its present form; and innumerable less complete indications of -the mode of evolution of other groups of the higher mammalia have been -obtained. In the remarkable memoir on the phosphorites of Quercy, to -which I have referred, M. Filhol describes no fewer than seventeen -varieties of the genus _Cynodictis_, which fill up all the interval -between the viverine animals and the bear-like dog _Amphicyon_; nor -do I know any solid ground of objection to the supposition that, in -this _Cynodictis-Amphicyon_ group, we have the stock whence all the -Viveridæ, Felidæ, Hyænidæ, Canidæ, and perhaps the Procyonidæ and -Ursidæ, of the present fauna have been evolved. On the contrary, there -is a great deal to be said in favour. - -In the course of summing up his results, M. Filhol observes:— - - “During the epoch of the phosphorites, great changes took - place in animal forms, and almost the same types as those - which now exist became defined from one another. - - “Under the influence of natural conditions of which - we have no exact knowledge, though traces of them are - discoverable, species have been modified in a thousand - ways: races have arisen which, becoming fixed, have thus - produced a corresponding number of secondary species.” - -In 1859, language of which this is an unintentional paraphrase, -occurring in the “Origin of Species,” was scouted as wild speculation; -at present, it is a sober statement of the conclusions to which an -acute and critically-minded investigator is led by large and patient -study of the facts of palæontology. I venture to repeat what I have -said before, that, so far as the animal world is concerned, evolution -is no longer a speculation, but a statement of historical fact. It -takes its place alongside of those accepted truths which must be -reckoned with by philosophers of all schools. - -Thus when, on the first day of October next, the “Origin of Species” -comes of age, the promise of its youth will be amply fulfilled; and we -shall be prepared to congratulate the venerated author of the book, not -only that the greatness of his achievement and its enduring influence -upon the progress of knowledge have won him a place beside our Harvey; -but, still more, that, like Harvey, he has lived long enough to outlast -detraction and opposition, and to see the stone that the builders -rejected become the head-stone of the corner. - - - - -XIII. - -THE CONNECTION OF THE BIOLOGICAL SCIENCES WITH MEDICINE. - - -The great body of theoretical and practical knowledge which has been -accumulated by the labours of some eighty generations, since the dawn -of scientific thought in Europe, has no collective English name to -which an objection may not be raised; and I use the term “medicine” as -that which is least likely to be misunderstood; though, as every one -knows, the name is commonly applied, in a narrower sense, to one of the -chief divisions of the totality of medical science. - -Taken in this broad sense, “medicine” not merely denotes a kind -of knowledge, but it comprehends the various applications of that -knowledge to the alleviation of the sufferings, the repair of the -injuries, and the conservation of the health, of living beings. In -fact, the practical aspect of medicine so far dominates over every -other, that the “Healing Art” is one of its most widely-received -synonyms. It is so difficult to think of medicine otherwise than as -something which is necessarily connected with curative treatment, that -we are apt to forget that there must be, and is, such a thing as a -pure science of medicine—a “pathology” which has no more necessary -subservience to practical ends than has zoology or botany. - -The logical connection between this purely scientific doctrine of -disease, or pathology, and ordinary biology, is easily traced. -Living matter is characterised by its innate tendency to exhibit a -definite series of the morphological and physiological phenomena which -constitute organisation and life. Given a certain range of conditions, -and these phenomena remain the same, within narrow limits, for each -kind of living thing. They furnish the normal and typical character -of the species, and, as such, they are the subject-matter of ordinary -biology. - -Outside the range of these conditions, the normal course of the -cycle of vital phenomena is disturbed; abnormal structure makes its -appearance, or the proper character and mutual adjustment of the -functions cease to be preserved. The extent and the importance of these -deviations from the typical life may vary indefinitely. They may have -no noticeable influence on the general well-being of the economy, or -they may favour it. On the other hand, they may be of such a nature -as to impede the activities of the organism, or even to involve its -destruction. - -In the first case, these perturbations are ranged under the wide and -somewhat vague category of “variations;” in the second, they are called -lesions, states of poisoning, or diseases; and, as morbid states, they -lie within the province of pathology. No sharp line of demarcation can -be drawn between the two classes of phenomena. No one can say where -anatomical variations end and tumours begin, nor where modification -of function, which may at first promote health, passes into disease. -All that can be said is, that whatever change of structure or function -is hurtful belongs to pathology. Hence it is obvious that pathology -is a branch of biology; it is the morphology, the physiology, the -distribution, the ætiology of abnormal life. - -However obvious this conclusion may be now, it was nowise apparent -in the infancy of medicine. For it is a peculiarity of the physical -sciences, that they are independent in proportion as they are -imperfect; and it is only as they advance that the bonds which really -unite them all become apparent. Astronomy had no manifest connection -with terrestrial physics before the publication of the “Principia;” -that of chemistry with physics is of still more modern revelation; -that of physics and chemistry with physiology, has been stoutly denied -within the recollection of most of us, and perhaps still may be. - -Or, to take a case which affords a closer parallel with that of -medicine. Agriculture has been cultivated from the earliest times, -and, from a remote antiquity, men have attained considerable practical -skill in the cultivation of the useful plants, and have empirically -established many scientific truths concerning the conditions under -which they flourish. But, it is within the memory of many of us, that -chemistry on the one hand, and vegetable physiology on the other, -attained a stage of development such that they were able to furnish -a sound basis for scientific agriculture. Similarly, medicine took -its rise in the practical needs of mankind. At first, studied without -reference to any other branch of knowledge, it long maintained, indeed -still to some extent maintains, that independence. Historically, its -connection with the biological sciences has been slowly established, -and the full extent and intimacy of that connection are only now -beginning to be apparent. I trust I have not been mistaken in supposing -that an attempt to give a brief sketch of the steps by which a -philosophical necessity has become an historical reality, may not be -devoid of interest, possibly of instruction, to the members of this -great Congress, profoundly interested as all are in the scientific -development of medicine. - -The history of medicine is more complete and fuller than that of any -other science, except, perhaps, astronomy; and, if we follow back the -long record as far as clear evidence lights us, we find ourselves taken -to the early stages of the civilisation of Greece. The oldest hospitals -were the temples of Æsculapius; to these Asclepeia, always erected on -healthy sites, hard by fresh springs and surrounded by shady groves, -the sick and the maimed resorted to seek the aid of the god of health. -Votive tablets or inscriptions recorded the symptoms, no less than the -gratitude, of those who were healed; and, from these primitive clinical -records, the half-priestly, half-philosophic caste of the Asclepiads -compiled the data upon which the earliest generalisations of medicine, -as an inductive science, were based. - -In this state, pathology, like all the inductive sciences at their -origin, was merely natural history; it registered the phenomena of -disease, classified them, and ventured upon a prognosis, wherever -the observation of constant co-existences and sequences suggested a -rational expectation of the like recurrence under similar circumstances. - -Further than this it hardly went. In fact, in the then state of -knowledge, and in the condition of philosophical speculation at that -time, neither the causes of the morbid state, nor the _rationale_ of -treatment, were likely to be sought for as we seek for them now. The -anger of a god was a sufficient reason for the existence of a malady, -and a dream ample warranty for therapeutic measures; that a physical -phenomenon must needs have a physical cause was not the implied or -expressed axiom that it is to us moderns. - -The great man whose name is inseparately connected with the foundation -of medicine, Hippocrates, certainly knew very little, indeed -practically nothing, of anatomy or physiology; and he would, probably, -have been perplexed, even to imagine the possibility of a connection -between the zoological studies of his contemporary Democritus and -medicine. Nevertheless, in so far as he, and those who worked before -and after him, in the same spirit, ascertained, as matters of -experience, that a wound, or a luxation, or a fever, presented such -and such symptoms, and that the return of the patient to health was -facilitated by such and such measures, they established laws of -nature, and began the construction of the science of pathology. All -true science begins with empiricism—though all true science is such -exactly, in so far as it strives to pass out of the empirical stage -into that of the deduction of empirical from more general truths. -Thus, it is not wonderful, that the early physicians had little or -nothing to do with the development of biological science; and, on the -other hand, that the early biologists did not much concern themselves -with medicine. There is nothing to show that the Asclepiads took any -prominent share in the work of founding anatomy, physiology, zoology, -and botany. Rather do these seem to have sprung from the early -philosophers, who were essentially natural philosophers, animated by -the characteristically Greek thirst for knowledge as such. Pythagoras, -Alcmeon, Democritus, Diogenes of Apollonia, are all credited with -anatomical and physiological investigations; and, though Aristotle is -said to have belonged to an Asclepiad family, and not improbably owed -his taste for anatomical and zoological inquiries to the teachings of -his father, the physician Nicomachus, the “Historia Animalium,” and -the treatise “De Partibus Animalium,” are as free from any allusion to -medicine as if they had issued from a modern biological laboratory. - -It may be added, that it is not easy to see in what way it could have -benefited a physician of Alexander’s time to know all that Aristotle -knew on these subjects. His human anatomy was too rough to avail -much in diagnosis; his physiology was too erroneous to supply data -for pathological reasoning. But when the Alexandrian school, with -Erasistratus and Herophilus at their head, turned to account the -opportunities of studying human structure, afforded to them by the -Ptolemies, the value of the large amount of accurate knowledge thus -obtained to the surgeon for his operations, and to the physician for -his diagnosis of internal disorders, became obvious, and a connection -was established between anatomy and medicine, which has ever become -closer and closer. Since the revival of learning, surgery, medical -diagnosis, and anatomy have gone hand in hand. Morgagni called his -great work, “De sedibus et causis morborum per anatomen indagatis,” and -not only showed the way to search out the localities and the causes -of disease by anatomy, but himself travelled wonderfully far upon the -road. Bichat, discriminating the grosser constituents of the organs and -parts of the body, one from another, pointed out the direction which -modern research must take; until, at length, histology, a science of -yesterday, as it seems to many of us, has carried the work of Morgagni -as far as the microscope can take us, and has extended the realm of -pathological anatomy to the limits of the invisible world. - -Thanks to the intimate alliance of morphology with medicine, the -natural history of disease has, at the present day, attained a -high degree of perfection. Accurate regional anatomy has rendered -practicable the exploration of the most hidden parts of the organism, -and the determination, during life, of morbid changes in them; -anatomical and histological postmortem investigations have supplied -physicians with a clear basis upon which to rest the classification -of diseases, and with unerring tests of the accuracy or inaccuracy of -their diagnoses. - -If men could be satisfied with pure knowledge, the extreme precision -with which, in these days, a sufferer may be told what is happening, -and what is likely to happen, even in the most recondite parts of -his bodily frame, should be as satisfactory to the patient as it is -to the scientific pathologist who gives him the information. But I -am afraid it is not; and even the practising physician, while nowise -underestimating the regulative value of accurate diagnosis, must often -lament that so much of his knowledge rather prevents him from doing -wrong than helps him to do right. - -A scorner of physic once said that nature and disease may be compared -to two men fighting, the doctor to a blind man with a club, who strikes -into the _melée_, sometimes hitting the disease, and sometimes hitting -nature. The matter is not mended if you suppose the blind man’s hearing -to be so acute that he can register every stage of the struggle, and -pretty clearly predict how it will end. He had better not meddle at -all, until his eyes are opened—until he can see the exact position of -the antagonists, and make sure of the effect of his blows. But that -which it behoves the physician to see, not, indeed, with his bodily -eye, but with clear, intellectual vision, is a process, and the chain -of causation involved in that process. Disease, as we have seen, is -a perturbation of the normal activities of a living body, and it is, -and must remain, unintelligible, so long as we are ignorant of the -nature of these normal activities. In other words, there could be no -real science of pathology until the science of physiology had reached a -degree of perfection unattained, and indeed unattainable, until quite -recent times. - -So far as medicine is concerned, I am not sure that physiology, such -as it was down to the time of Harvey, might as well not have existed. -Nay, it is perhaps no exaggeration to say that, within the memory of -living men, justly renowned practitioners of medicine and surgery knew -less physiology than is now to be learned from the most elementary -text-book; and, beyond a few broad facts, regarded what they did know -as of extremely little practical importance. Nor am I disposed to -blame them for this conclusion; physiology must be useless, or worse -than useless, to pathology, so long as its fundamental conceptions are -erroneous. - -Harvey is often said to be the founder of modern physiology; and there -can be no question that the elucidations of the function of the heart, -of the nature of the pulse, and of the course of the blood, put forth -in the ever-memorable little essay, “De motu cordis,” directly worked -a revolution in men’s views of the nature and of the concatenation of -some of the most important physiological processes among the higher -animals; while, indirectly, their influence was perhaps even more -remarkable. - -But, though Harvey made this signal and perennially important -contribution to the physiology of the moderns, his general conception -of vital processes was essentially identical with that of the ancients; -and, in the “Exercitationes de generatione,” and notably in the -singular chapter “De calido innato,” he shows himself a true son of -Galen and of Aristotle. - -For Harvey, the blood possesses powers superior to those of the -elements; it is the seat of a soul which is not only vegetative, but -also sensitive and motor. The blood maintains and fashions all parts of -the body, “idque summâ cum providentiâ et intellectu in finem certum -agens, quasi ratiocinio quodam uteretur.” - -Here is the doctrine of the “pneuma,” the product of the philosophical -mould into which the animism of primitive men ran in Greece, in full -force. Nor did its strength abate for long after Harvey’s time. The -same ingrained tendency of the human mind to suppose that a process -is explained when it is ascribed to a power of which nothing is known -except that it is the hypothetical agent of the process, gave rise, in -the next century, to the animism of Stahl; and, later, to the doctrine -of a vital principle, that “asylum ignorantiæ” of physiologists, which -has so easily accounted for everything and explained nothing, down to -our own times. - -Now the essence of modern, as contrasted with ancient, physiological -science appears to me to lie in its antagonism to animistic hypotheses -and animistic phraseology. It offers physical explanations of vital -phenomena, or frankly confesses that it has none to offer. And, so far -as I know, the first person who gave expression to this modern view -of physiology, who was bold enough to enunciate the proposition that -vital phenomena, like all the other phenomena of the physical world, -are, in ultimate analysis, resolvable into matter and motion, was René -Descartes. - -The fifty-four years of life of this most original and powerful thinker -are widely overlapped, on both sides, by the eighty of Harvey, who -survived his younger contemporary by seven years, and takes pleasure -in acknowledging the French philosopher’s appreciation of his great -discovery. - -In fact, Descartes accepted the doctrine of the circulation as -propounded by “Harvæus médecin d’Angleterre,” and gave a full account -of it in his first work, the famous “Discours de la Méthode,” which -was published in 1637, only nine years after the exercitation “De motu -cordis;” and, though differing from Harvey on some important points -(in which it may be noted, in passing, Descartes was wrong and Harvey -right), he always speaks of him with great respect. And so important -does the subject seem to Descartes, that he returns to it in the -“Traité des Passions,” and in the “Traité de l’Homme.” - -It is easy to see that Harvey’s work must have had a peculiar -significance for the subtle thinker, to whom we owe both the -spiritualistic and the materialistic philosophies of modern times. It -was in the very year of its publication, 1628, that Descartes withdrew -into that life of solitary investigation and meditation of which his -philosophy was the fruit. And, as the course of his speculations -led him to establish an absolute distinction of nature between the -material and the mental worlds, he was logically compelled to seek -for the explanation of the phenomena of the material world within -itself; and having allotted the realm of thought to the soul, to see -nothing but extension and motion in the rest of nature. Descartes uses -“thought” as the equivalent of our modern term “consciousness.” Thought -is the function of the soul, and its only function. Our natural heat -and all the movements of the body, says he, do not depend on the soul. -Death does not take place from any fault of the soul, but only because -some of the principal parts of the body become corrupted. The body of a -living man differs from that of a dead man in the same way as a watch -or other automaton (that is to say, a machine which moves of itself) -when it is wound up and has, in itself, the physical principle of the -movements which the mechanism is adapted to perform, differs from the -same watch, or other machine, when it is broken, and the physical -principle of its movement no longer exists. All the actions which are -common to us and the lower animals depend only on the conformation of -our organs, and the course which the animal spirits take in the brain, -the nerves, and the muscles; in the same way as the movement of a watch -is produced by nothing but the force of its spring and the figure of -its wheels and other parts. - -Descartes’ “Treatise on Man” is a sketch of human physiology, in which -a bold attempt is made to explain all the phenomena of life, except -those of consciousness, by physical reasonings. To a mind turned in -this direction, Harvey’s exposition of the heart and vessels as a -hydraulic mechanism must have been supremely welcome. - -Descartes was not a mere philosophical theorist, but a hardworking -dissector and experimenter, and he held the strongest opinion -respecting the practical value of the new conception which he was -introducing. He speaks of the importance of preserving health, and of -the dependence of the mind on the body being so close that, perhaps, -the only way of making men wiser and better than they are, is to be -sought in medical science. “It is true,” says he, “that as medicine -is now practised, it contains little that is very useful; but without -any desire to depreciate, I am sure that there is no one, even among -professional men, who will not declare that all we know is very little -as compared with that which remains to be known; and that we might -escape an infinity of diseases of the mind, no less than of the body, -and even perhaps from the weakness of old age, if we had sufficient -knowledge of their causes, and of all the remedies with which nature -has provided us.”[96] So strongly impressed was Descartes with this, -that he resolved to spend the rest of his life in trying to acquire -such a knowledge of nature as would lead to the construction of a -better medical doctrine.[97] The anti-Cartesians found material for -cheap ridicule in these aspirations of the philosopher; and it is -almost needless to say that, in the thirteen years which elapsed -between the publication of the “Discours” and the death of Descartes, -he did not contribute much to their realisation. But, for the next -century, all progress in physiology took place along the lines which -Descartes laid down. - -The greatest physiological and pathological work of the seventeenth -century, Borelli’s treatise “De Motu Animalium,” is, to all intents -and purposes, a development of Descartes’ fundamental conception; and -the same may be said of the physiology and pathology of Boerhaave, -whose authority dominated in the medical world of the first half of the -eighteenth century. - -With the origin of modern chemistry, and of electrical science, in the -latter half of the eighteenth century, aids in the analysis of the -phenomena of life, of which Descartes could not have dreamed, were -offered to the physiologist. And the greater part of the gigantic -progress which has been made in the present century is a justification -of the prevision of Descartes. For it consists, essentially, in a more -and more complete resolution of the grosser organs of the living body -into physico-chemical mechanisms. - -“I shall try to explain our whole bodily machinery in such a way, that -it will be no more necessary for us to suppose that the soul produces -such movements as are not voluntary, than it is to think that there is -in a clock a soul which causes it to show the hours.”[98] These words -of Descartes might be appropriately taken as a motto by the author of -any modern treatise on physiology. - -But though, as I think, there is no doubt that Descartes was the -first to propound the fundamental conception of the living body as -a physical mechanism, which is the distinctive feature of modern, -as contrasted with ancient physiology, he was misled by the natural -temptation to carry out, in all its details, a parallel between the -machines with which he was familiar, such as clocks and pieces of -hydraulic apparatus, and the living machine. In all such machines there -is a central source of power, and the parts of the machine are merely -passive distributors of that power. The Cartesian school conceived -of the living body as a machine of this kind; and herein they might -have learned from Galen, who, whatever ill use he may have made of the -doctrine of “natural faculties,” nevertheless had the great merit of -perceiving that local forces play a great part in physiology. - -The same truth was recognised by Glisson, but it was first prominently -brought forward in the Hallerian doctrine of the “vis insita” of -muscles. If muscle can contract without nerve, there is an end of the -Cartesian mechanical explanation of its contraction by the influx of -animal spirits. - -The discoveries of Trembley tended in the same direction. In the -freshwater _Hydra_, no trace was to be found of that complicated -machinery upon which the performance of the functions in the higher -animals was supposed to depend. And yet the hydra moved, fed, grew, -multiplied, and its fragments exhibited all the powers of the whole. -And, finally, the work of Caspar F. Wolff,[99] by demonstrating the -fact that the growth and development of both plants and animals take -place antecedently to the existence of their grosser organs, and are, -in fact, the causes and not the consequences of organisation (as then -understood), sapped the foundations of the Cartesian physiology as a -complete expression of vital phenomena. - -For Wolff, the physical basis of life is a fluid, possessed of a “vis -essentialis” and a “solidescibilitas,” in virtue of which it gives rise -to organisation; and, as he points out, this conclusion strikes at the -root of the whole iatro-mechanical system. - -In this country, the great authority of John Hunter exerted a similar -influence; though it must be admitted that the too sibylline utterances -which are the outcome of Hunter’s struggles to define his conceptions -are often susceptible of more than one interpretation. Nevertheless, -on some points Hunter is clear enough. For example, he is of opinion -that “Spirit is only a property of matter” (“Introduction to Natural -History,” p. 6), he is prepared to renounce animism (_l.c._ p. 8), -and his conception of life is so completely physical that he thinks -of it as something which can exist in a state of combination in the -food. “The aliment we take in has in it, in a fixed state, the real -life; and this does not become active until it has got into the lungs; -for there it is freed from its prison” (“Observations on Physiology,” -p. 113). He also thinks that “It is more in accord with the general -principles of the animal machine to suppose that none of its effects -are produced from any mechanical principle whatever; and that every -effect is produced from an action in the part; which action is produced -by a stimulus upon the part which acts, or upon some other part with -which this part sympathises so as to take up the whole action” (_l.c._ -p. 152). - -And Hunter is as clear as Wolff, with whose work he was probably -unacquainted, that “whatever life is, it most certainly does not depend -upon structure or organisation” (_l.c._ p. 114). - -Of course it is impossible that Hunter could have intended to deny -the existence of purely mechanical operations in the animal body. -But while, with Borelli and Boerhaave, he looked upon absorption, -nutrition, and secretion as operations effected by means of the small -vessels, he differed from the mechanical physiologists, who regarded -these operations as the result of the mechanical properties of the -small vessels, such as the size, form, and disposition of their canals -and apertures. Hunter, on the contrary, considers them to be the effect -of properties of these vessels which are not mechanical but vital. “The -vessels,” says he, “have more of the polypus in them than any other -part of the body,” and he talks of the “living and sensitive principles -of the arteries,” and even of the “dispositions or feelings of the -arteries.” “When the blood is good and genuine the sensations of the -arteries, or the dispositions for sensation, are agreeable.... It is -then they dispose of the blood to the best advantage, increasing the -growth of the whole, supplying any losses, keeping up a due succession, -etc.” (_l.c._ p. 133). - -If we follow Hunter’s conceptions to their logical issue, the life of -one of the higher animals is essentially the sum of the lives of all -the vessels, each of which is a sort of physiological unit, answering -to a polype; and, as health is the result of the normal “action of the -vessels,” so is disease an effect of their abnormal action. Hunter thus -stands in thought, as in time, midway between Borelli on the one hand, -and Bichat on the other. - -The acute founder of general anatomy, in fact, outdoes Hunter in his -desire to exclude physical reasonings from the realm of life. Except in -the interpretation of the action of the sense organs, he will not allow -physics to have anything to do with physiology. - -“To apply the physical sciences to physiology is to explain the -phenomena of living bodies by the laws of inert bodies. Now this -is a false principle, hence all its consequences are marked with -the same stamp. Let us leave to chemistry its affinity; to physics, -its elasticity and its gravity. Let us invoke for physiology only -sensibility and contractility.”[100] - -Of all the unfortunate dicta of men of eminent ability this seems -one of the most unhappy, when we think of what the application of -the methods and the data of physics and chemistry has done towards -bringing physiology into its present state. It is not too much to say -that one half of a modern text-book of physiology consists of applied -physics and chemistry; and that it is exactly in the exploration of the -phenomena of sensibility and contractility that physics and chemistry -have exerted the most potent influence. - -Nevertheless, Bichat rendered a solid service to physiological progress -by insisting upon the fact that what we call life, in one of the higher -animals, is not an indivisible unitary archæus dominating, from its -central seat, the parts of the organism, but a compound result of the -synthesis of the separate lives of those parts. - -“All animals,” says he, “are assemblages of different organs, each of -which performs its function and concurs, after its fashion, in the -preservation of the whole. They are so many special machines in the -general machine which constitutes the individual. But each of these -special machines is itself compounded of many tissues of very different -natures, which in truth constitute the elements of those organs” -(_l.c._ lxxix.) “The conception of a proper vitality is applicable only -to these simple tissues, and not to the organs themselves” (_l.c._ -lxxxiv.) - -And Bichat proceeds to make the obvious application of this doctrine of -synthetic life, if I may so call it, to pathology. Since diseases are -only alterations of vital properties, and the properties of each tissue -are distinct from those of the rest, it is evident that the diseases of -each tissue must be different from those of the rest. Therefore, in any -organ composed of different tissues, one may be diseased and the other -remain healthy; and this is what happens in most cases (_l.c._ lxxxv.) - -In a spirit of true prophecy, Bichat says, “We have arrived at an -epoch, in which pathological anatomy should start afresh.” For, as the -analysis of the organs had led him to the tissues, as the physiological -units of the organism; so, in a succeeding generation, the analysis -of the tissues led to the cell as the physiological element of the -tissues. The contemporaneous study of development brought out the same -result; and the zoologists and botanists, exploring the simplest and -the lowest forms of animated beings, confirmed the great induction of -the cell theory. Thus the apparently opposed views, which have been -battling with one another ever since the middle of the last century, -have proved to be each half the truth. - -The proposition of Descartes that the body of a living man is a -machine, the actions of which are explicable by the known laws of -matter and motion, is unquestionably largely true. But it is also -true, that the living body is a synthesis of innumerable physiological -elements, each of which may nearly be described, in Wolff’s words, as a -fluid possessed of a “vis essentialis,” and a “solidescibilitas”; or, -in modern phrase, as protoplasm susceptible of structural metamorphosis -and functional metabolism: and that the only machinery, in the precise -sense in which the Cartesian school understood mechanism, is, that -which co-ordinates and regulates these physiological units into an -organic whole. - -In fact, the body is a machine of the nature of an army, not of that -of a watch or of a hydraulic apparatus. Of this army each cell is a -soldier, an organ a brigade, the central nervous system headquarters -and field telegraph, the alimentary and circulatory system the -commissariat. Losses are made good by recruits born in camp, and the -life of the individual is a campaign, conducted successfully for a -number of years, but with certain defeat in the long run. - -The efficacy of an army, at any given moment, depends on the health of -the individual soldier, and on the perfection of the machinery by which -he is led and brought into action at the proper time; and, therefore, -if the analogy holds good, there can be only two kinds of diseases, the -one dependent on abnormal states of the physiological units, the other -on perturbations of their co-ordinating and alimentative machinery. - -Hence, the establishment of the cell theory, in normal biology, was -swiftly followed by a “cellular pathology,” as its logical counterpart. -I need not remind you how great an instrument of investigation this -doctrine has proved in the hands of the man of genius to whom its -development is due, and who would probably be the last to forget that -abnormal conditions of the co-ordinative and distributive machinery of -the body are no less important factors of disease. - -Henceforward, as it appears to me, the connection of medicine with the -biological sciences is clearly defined. Pure pathology is that branch -of biology which defines the particular perturbation of cell-life, or -of the co-ordinating machinery, or of both, on which the phenomena of -disease depend. - -Those who are conversant with the present state of biology will hardly -hesitate to admit that the conception of the life of one of the higher -animals as the summation of the lives of a cell aggregate, brought into -harmonious action by a co-ordinative machinery formed by some of these -cells, constitutes a permanent acquisition of physiological science. -But the last form of the battle between the animistic and the physical -views of life is seen in the contention whether the physical analysis -of vital phenomena can be carried beyond this point or not. - -There are some to whom living protoplasm is a substance, even such as -Harvey conceived the blood to be, “summâ cum providentiâ et intellectu -in finem certum agens, quasi ratiocinio quodam;” and who look with as -little favour as Bichat did, upon any attempt to apply the principles -and the methods of physics and chemistry to the investigation of the -vital processes of growth, metabolism, and contractility. They stand -upon the ancient ways; only, in accordance with that progress towards -democracy, which a great political writer has declared to be the fatal -characteristic of modern times, they substitute a republic formed by a -few billion of “animulæ” for the monarchy of the all-pervading “anima.” - -Others, on the contrary, supported by a robust faith in the universal -applicability of the principles laid down by Descartes, and seeing -that the actions called “vital” are, so far as we have any means of -knowing, nothing but changes of place of particles of matter, look to -molecular physics to achieve the analysis of the living protoplasm -itself into a molecular mechanism. If there is any truth in the -received doctrines of physics, that contrast between living and inert -matter, on which Bichat lays so much stress, does not exist. In nature, -nothing is at rest, nothing is amorphous; the simplest particle of -that which men in their blindness are pleased to call “brute matter” -is a vast aggregate of molecular mechanisms performing complicated -movements of immense rapidity, and sensitively adjusting themselves -to every change in the surrounding world. Living matter differs from -other matter in degree and not in kind; the microcosm repeats the -macrocosm; and one chain of causation connects the nebulous original of -suns and planetary systems with the protoplasmic foundation of life and -organisation. - -From this point of view, pathology is the analogue of the theory of -perturbations in astronomy; and therapeutics resolves itself into -the discovery of the means by which a system of forces competent to -eliminate any given perturbation may be introduced into the economy. -And, as pathology bases itself upon normal physiology, so therapeutics -rests upon pharmacology; which is, strictly speaking, a part of the -great biological topic of the influence of conditions on the living -organism, and has no scientific foundation apart from physiology. - -It appears to me that there is no more hopeful indication of the -progress of medicine towards the ideal of Descartes than is to -be derived from a comparison of the state of pharmacology, at the -present day, with that which existed forty years ago. If we consider -the knowledge positively acquired, in this short time, of the _modus -operandi_ of urari, of atropia, of physostigmin, of veratria, of casca, -of strychnia, of bromide of potassium, of phosphorus, there can surely -be no ground for doubting that, sooner or later, the pharmacologist -will supply the physician with the means of affecting, in any desired -sense, the functions of any physiological element of the body. It will, -in short, become possible to introduce into the economy a molecular -mechanism which, like a very cunningly-contrived torpedo, shall find -its way to some particular group of living elements, and cause an -explosion among them, leaving the rest untouched. - -The search for the explanation of diseased states in modified -cell-life; the discovery of the important part played by parasitic -organisms in the ætiology of disease; the elucidation of the action of -medicaments by the methods and the data of experimental physiology; -appear to me to be the greatest steps which have ever been made towards -the establishment of medicine on a scientific basis. I need hardly say -they could not have been made except for the advance of normal biology. - -There can be no question, then, as to the nature or the value of the -connection between medicine and the biological sciences. There can -be no doubt that the future of pathology and of therapeutics, and, -therefore, that of practical medicine, depends upon the extent to -which those who occupy themselves with these subjects are trained in -the methods and impregnated with the fundamental truths of biology. - -And, in conclusion, I venture to suggest that the collective sagacity -of this Congress could occupy itself with no more important question -than with this: How is medical education to be arranged, so that, -without entangling the student in those details of the systematist -which are valueless to him, he may be enabled to obtain a firm grasp of -the great truths respecting animal and vegetable life, without which, -notwithstanding all the progress of scientific medicine, he will still -find himself an empiric? - - - - -FOOTNOTES: - -[1] See _Joseph Priestley_, p. 94, _infra_. - -[2] The advocacy of the introduction of physical science into general -education by George Combe and others commenced a good deal earlier; but -the movement had acquired hardly any practical force before the time to -which I refer. - -[3] _Essays in Criticism_, p. 37. - -[4] “Quamvis enim melius sit bene facere quam nosse, prius tamen est -nosse quam facere.”—“Karoli Magni Regis Constitutio de Scholis per -singula Episcopia et Monasteria instituendis,” addressed to the Abbot -of Fulda. Baluzius, “Capitularia Regum Francorum,” T. i., p. 202. - -[5] Inaugural Address delivered to the University of St. Andrew -February 1, 1867, by J. S. Mill, Rector of the University (pp. 32, 33). - -[6] “Suggestions for Academical Organisation, with Especial Reference -to Oxford.” By the Rector of Lincoln. - -[7] Goethe, _Zahme Xenien, Vierte Abtheilung_. I should be glad to take -credit for the close and vigorous English version; but it is my wife’s, -and not mine. - -[8] See the “Programme” for 1878, issued by the Society of Arts, p. 14. - -[9] It is perhaps advisable to remark that the important question of -the professional education of managers of industrial works is not -touched in the foregoing remarks. - -[10] “Quasi cursores, vitaï lampada tradunt.”—LUCR. _De Rerum Nat._ ii. -78. - -[11] “Life and Correspondence of Dr. Priestley,” by J. T. Rutt. Vol. i. -p. 50. - -[12] “Autobiography,” §§ 100, 101. - -[13] See “The Life of Mary Anne Schimmelpenninck.” Mrs. -Schimmelpenninck (_née_ Galton) remembered Priestley very well, and her -description of him is worth quotation:—“A man of admirable simplicity, -gentleness and kindness of heart, united with great acuteness of -intellect. I can never forget the impression produced on me by the -serene expression of his countenance. He, indeed, seemed present with -God by recollection, and with man by cheerfulness. I remember that, -in the assembly of these distinguished men, amongst whom Mr. Boulton, -by his noble manner, his fine countenance (which much resembled that -of Louis XIV.), and princely munificence, stood pre-eminently as the -great Mecænas; even as a child, I used to feel, when Dr. Priestley -entered after him, that the glory of the one was terrestrial, that of -the other celestial; and utterly far as I am removed from a belief in -the sufficiency of Dr. Priestley’s theological creed, I cannot but here -record this evidence of the eternal power of any portion of the truth -held in its vitality.” - -[14] Even Mrs. Priestley, who might be forgiven for regarding the -destroyers of her household gods with some asperity, contents herself, -in writing to Mrs. Barbauld, with the sarcasm that the Birmingham -people “will scarcely find so many respectable characters, a second -time, to make a bonfire of.” - -[15] “Experiments and Observations on Different Kinds of Air,” vol. ii. -p. 31. - -[16] _Ibid._ pp. 34, 35. - -[17] “Experiments and Observations on Different Kinds of Air,” vol. ii. -p. 40. - -[18] _Ibid._ p. 48. - -[19] _Ibid._ p. 55. - -[20] “Experiments and Observations on Different Kinds of Air,” vol. ii. -p. 60. The italics are Priestley’s own. - -[21] “In all the newspapers and most of the periodical publications -I was represented as an unbeliever in Revelation, and no better than -an atheist.”—“Autobiography,” Rutt. vol. i. p. 124. “On the walls of -houses, etc., and especially where I usually went, were to be seen, in -large characters, ‘MADAN FOR EVER; DAMN PRIESTLEY; NO PRESBYTERIANISM; -DAMN THE PRESBYTERIANS,’ etc. etc.; and, at one time, I was followed by -a number of boys, who left their play, repeating what they had seen on -the walls, and shouting out, ‘_Damn Priestley; damn him, damn him, for -ever, for ever_,’ etc. etc. This was no doubt a lesson which they had -been taught by their parents, and what they, I fear, had learned from -their superiors.”—“Appeal to the Public on the Subject of the Riots at -Birmingham.” - -[22] First Series. “On Some of the Peculiarities of the Christian -Religion.” Essay I. Revelation of a Future State. - -[23] Not only is Priestley at one with Bishop Courtenay in this -matter, but with Hartley and Bonnet, both of them stout champions of -Christianity. Moreover, Archbishop Whately’s essay is little better -than an expansion of the first paragraph of Hume’s famous essay on -the Immortality of the Soul:—“By the mere light of reason it seems -difficult to prove the immortality of the soul; the arguments for it -are commonly derived either from metaphysical topics, or moral, or -physical. But it is in reality the Gospel, and the Gospel alone, that -has brought _life and immortality to light_.” It is impossible to -imagine that a man of Whately’s tastes and acquirements had not read -Hume or Hartley, though he refers to neither. - -[24] “Essay on the First Principles of Government.” Second edition, -1771, p. 13. - -[25] “Utility of Establishments,” in “Essay on First Principles of -Government,” p. 198, 1771. - -[26] In 1732 Doddridge was cited for teaching without the Bishop’s -leave, at Northampton. - -[27] The recent proceedings of the House of Commons throw a doubt, -which it is to be hoped may speedily be removed, on the accuracy of -this statement. (September 1881.) - -[28] “Discours sur les révolutions de la surface du globe,” _Recherches -sur les ossemens fossiles_, Ed. iv. t. i. p. 185. - -[29] “On the Eclipses of Agathocles, Thales, and Xerxes,” -_Philosophical Transactions_, vol. cxliii. - -[30] There is every reason to believe that living plants, like living -animals, always respire, and, in respiring, absorb oxygen and give off -carbonic acid; but, that in green plants exposed to daylight or to -the electric light, the quantity of oxygen evolved in consequence of -the decomposition of carbonic acid by a special apparatus which green -plants possess exceeds that absorbed in the concurrent respiratory -process. - -[31] Darwin, “Insectivorous Plants,” p. 289. - -[32] I purposely assume that the air with which the bean is supplied in -the case stated contains no ammoniacal salts. - -[33] The recent researches of Pringsheim have raised a host of -questions as to the exact share taken by chlorophyll in the chemical -operations which are effected by the green parts of plants. It may -be that the chlorophyll is only a constant concomitant of the actual -deoxidising apparatus. - -[34] “Researches in the Life-history of a Cercomonad: a Lesson in -Biogenesis;” and “Further Researches in the Life-history of the -Monads.”—“Monthly Microscopical Journal,” 1873. - -[35] Excellently described by Stein, almost all of whose statements I -have verified. - -[36] “Histoire des Sciences Naturelles,” i. p. 152. - -[37] The text I have followed is that given by Aubert and Wimmer, -“Aristoteles Thierkunde; kritisch berichtigter Text mit deutschen -Uebersetzung;” but I have tried here and there to bring the English -version rather closer to the original than the German translation, -excellent as it is, seems to me to be. - -[38] In modern works on Veterinary Anatomy the lungs are sometimes -described as two lobes of a single organ. - -[39] “Histoire des Sciences Naturelles.”—t. i. p. 130. - -[40] “Aristotle, a Chapter from the History of Science.” - -[41] I quote, here and always, Cousin’s edition of the works of -Descartes, as most convenient for reference. It is entitled “Œuvres -complètes de Descartes,” publiées par Victor Cousin. 1824. - -[42] “Les Passions de l’Âme,” Article xxxiii. - -[43] “Recherches physiologiques sur la Vie et la Mort.” Par Xav. -Bichat. Art. Sixième. - -[44] Locke (_Human Understanding_, Book II., chap. viii. 37) uses -Descartes’ illustration for the same purpose, and warns us that “most -of the ideas of sensation are no more the likeness of something -existing without us than the names that stand for them are the likeness -of our ideas, which yet, upon hearing, they are apt to excite in us,” a -declaration which paved the way for Berkeley. - -[45] “Passions de l’Âme,” Art. xxxvi. - -[46] “Quamcumque Bruti actionem, velut automati mechanici motum -artificialem, in eo consistere quod se primò sensibile aliquod spiritus -animales afficiens, eosque introrsum convertens, _sensionem_ excitat, -à qua mox iidem spiritus, velut undulatione reflexâ denuo retrorsum -commoti atque pro concinno ipsius fabricæ organorum, et partium ordine, -in certos nervos musculosque determinati, respectivos _membrorum motus_ -perficiunt.”—WILLIS: “De Animâ Brutorum,” p. 5, ed. 1763. - -[47] “Les Passions de l’Âme,” xlii. - -[48] Haller, “Primæ Lineæ,” ed. iii. “Sensus Interni,” dlviii. - -[49] “Réponse de M. Descartes à M. Morus.” 1649. “Œuvres,” tome x. p. -204. “Mais le plus grand de tous les préjugés que nous ayons retenus de -notre enfance, est celui de croire que les bêtes pensent,” etc. - -[50] Malebranche states the view taken by orthodox Cartesians in -1689 very forcibly: “Ainsi dans les chiens, les chats, et les autres -animaux, il n’y a ny intelligence, ny âme spirituelle comme on l’entend -ordinairement. Ils mangent sans plaisir; ils crient sans douleur; ils -croissent sans le sçavoir; ils ne désirent rien; ils ne connoissent -rien; et s’ils agissent avec adresse et d’une manière qui marque -l’intelligence, c’est que Dieu les faisant pour les conserver, il a -conformé leurs corps de telle manière, qu’ils évitent organiquement, -sans le sçavoir, tout ce qui peut les détruire et qu’ils semblent -craindre.” (“Feuillet de Conches. Méditations Métaphysiques et -Correspondance de N. Malebranche. Neuvième Méditation.” 1841.) - -[51] See the remarkable essay of Göltz, “Beiträge zur Lehre von den -Functionen der Nervencentren des Frosches,” published in 1869. I have -repeated Göltz’s experiments, and obtained the same results. - -[52] “De l’Automatisme de la Mémoire et du Souvenir, dans le -Somnambulisme pathologique.” Par le Dr. E. Mesnet, Médecin de l’Hôpital -Saint-Antoine. “L’Union Médicale,” Juillet 21 et 23, 1874. My attention -was first called to a summary of this remarkable case, which appeared -in the “Journal des Débats” for the 7th of August 1874, by my friend -General Strachey, F.R.S. - -[53] Those who have had occasion to become acquainted with the -phenomena of somnambulism and of mesmerism, will be struck with the -close parallel which they present to the proceedings of F. in his -abnormal state. But the great value of Dr. Mesnet’s observations lies -in the fact that the abnormal condition is traceable to a definite -injury to the brain, and that the circumstances are such as to keep -us clear of the cloud of voluntary and involuntary fictions in which -the truth is too often smothered in such cases. In the unfortunate -subjects of such abnormal conditions of the brain, the disturbance of -the sensory and intellectual faculties is not unfrequently accompanied -by a perturbation of the moral nature, which may manifest itself in a -most astonishing love of lying for its own sake. And, in this respect, -also, F.’s case is singularly instructive, for though, in his normal -state, he is a perfectly honest man, in his abnormal condition he is -an inveterate thief, stealing and hiding away whatever he can lay -hands on, with much dexterity, and with an absurd indifference as to -whether the property is his own or not. Hoffman’s terrible conception -of the “Doppelt-gänger” is realised by men in this state—who live two -lives, in the one of which they may be guilty of the most criminal -acts, while, in the other, they are eminently virtuous and respectable. -Neither life knows anything of the other. Dr. Mesnet states that he -has watched a man in his abnormal state elaborately prepare to hang -himself, and has let him go on until asphyxia set in, when he cut him -down. But on passing into the normal state the would-be suicide was -wholly ignorant of what had happened. The problem of responsibility is -here as complicated as that of the prince-bishop, who swore as a prince -and not as a bishop. “But, highness, if the prince is damned, what will -become of the bishop?” said the peasant. - -[54] “Lay Sermons, Essays and Reviews,” p. 355. - -[55] “Essai de Psychologie,” chap. xxvii. - -[56] In justice to Reid, however, it should be stated that the chapters -on sensation in the “Essays on the Intellectual Powers” (1785) exhibit -a great improvement. He is, in fact, in advance of his commentator, as -the note to Essay II. chap. ii. p. 248 of Hamilton’s edition shows. - -[57] Haller, amplifying Descartes, writes in the “Primæ Lineæ,” -CCCLXVI.—“Non est adeo obscurum sensum omnem oriri ab objecti -sensibilis impressione in nervum quemcumque corporis humani, et eamdem -per eum nervum ad cerebrum pervenientem tunc demum representari animæ, -quando cerebrum adtigit. Ut etiam hoc falsum sit animam inproximo per -sensoria nervorumque ramos sentire.”... DLVII.—“Dum ergo sentimus -quinque diversissima entia conjunguntur: corpus quod sentimus: -organi sensorii adfectio ab eo corpore: cerebri adfectio a sensorii -percussione nata: in anima nata mutatio: animæ denique conscientia et -sensationis adperceptio.” Nevertheless, Sir William Hamilton gravely -informs his hearers:—“We have no more right to deny that the mind feels -at the finger points, as consciousness assures us, than to assert -that it thinks exclusively in the brain.”—“Lecture on Metaphysics and -Logic,” ii. p. 128. “We have no reason whatever to doubt the report -of consciousness, that we actually perceive at the external point of -sensation, and that we perceive the material reality.”—_Ibid._ p. 129. - -[58] “Observations on Man,” vol. i. p. 11. - -[59] _Ibid._ p. 8. The speculations of Bonnet are remarkably similar -to those of Hartley; and they appear to have originated independently, -though the “Essai de Psychologie” (1754) is of five years’ later date -than the “Observations on Man” (1749). - -[60] “An Inquiry into the Human Mind on the Principles of Common -Sense,” chap. ii. § 2. Reid affirms that “it is genius, and not the -want of it, that adulterates philosophy, and fills it with error and -false theory;” and no doubt his own lucubrations are free from the -smallest taint of the impurity to which he objects. But, for want of -something more than that sort of “common sense,” which is very common -and a little dull, the contemner of genius did not notice that the -admission here made knocks so big a hole in the bottom of “common sense -philosophy,” that nothing can save it from foundering in the dreaded -abyss of Idealism. - -[61] The following diagrammatic scheme may help to elucidate the theory -of sensation:— - - Mediate Knowledge - ┌────────────────────────────┴──────────────────────────────┐ Immediate - Sensiferous Apparatus Knowledge - ┌─────────────────────┴────────────────────┐ ┌───────┴───────┐ - Objects of sense │ Receptive Transmissive Sensificatory │ Sensations and - │(Sense Organ) (Nerve) (Sensorium) │ other States of - │ │ Consciousness - │ │ - Hypothetical │ │ Hypothetical - Substance of │ │ Substance of - Matter │ │ Mind - - └──────────────────────────────────┬─────────────────────────┘ └───────┬───────┘ - Physical World Mental World - └───────┬───────┘└────────────────────────────┬────────────────────────────────┘ - Not Self Self - └───────────────────────────────┬────────────────────────────┘ └───────┬───────┘ - Non-Ego or Object Ego or Subject - -Immediate knowledge is confined to states of consciousness, or, in -other words, to the phenomena of mind. Knowledge of the physical -world, or of one’s own body and of objects external to it, is a system -of beliefs or judgments based on the sensations. The term “self” is -applied not only to the series of mental phenomena which constitute the -ego, but to the fragment of the physical world which is their constant -concomitant. The corporeal self, therefore, is part of the non-ego; -and is objective in relation to the ego as subject. - -[62] “Chaque fibre est une espèce de touche ou de marteau destiné à -rendre un certain ton.”—Bonnet, “Essai de Psychologie,” chap. iv. - -[63] The “Exercitationes de Generatione Animalium,” which Dr. George -Ent extracted from him and published in 1651. - -[64] “De Generatione Animalium,” lib ii. cap. x. - -[65] “De Generatione,” lib. ii. cap. iv. - -[66] “Cependant, pour revenir aux formes ordinaires ou aux âmes -matérielles, cette durée qu’il leur faut attribuer à la place de celle -qu’on avoit attributée aux atomes pourroit faire douter si elles ne -vont pas de corps en corps; ce qui seroit la métempsychose, à peu -près comme quelques philosophes ont cru la transmission du mouvement -et celle des espèces. Mais cette imagination est bien éloignée de la -nature des choses. Il n’y a point de tel passage; et c’est ici où les -transformations de Messieurs Swammerdam, Malpighi, et Leewenhoek, qui -sont des plus excellens observateurs de notre tems, sont venues à mon -secours, et m’ont fait admettre plus aisément, que l’animal, et toute -autre substance organisée ne commence point lorsque nous le croyons, et -que sa generation apparente n’est qu’une développement et une espèce -d’augmentation. Aussi ai je remarqué que l’auteur de la “Recherche de -la Verité,” M. Regis, M. Hartsocker, et d’autres habiles hommes n’ont -pas été fort éloignés de ce sentiment.” Leibnitz, “Système nouveau -de la Nature,” 1695. The doctrine of “Emboîtement” is contained in -the “Considérations sur le principe de vie,” 1705; the preface to the -“Theodicée,” 1710; and the “Principes de la Nature et de la Grace” (§ -6), 1718. - -[67] “Il est vrai que la pensée la plus raisonnable et la plus conforme -à l’experience sur cette question très difficile de la formation du -fœtus; c’est que les enfans sont déja presque tout formés avant même -l’action par laquelle ils sont conçus; et que leurs mères ne font que -leur donner l’accroissement ordinaire dans le temps de la grossesse.” -“De la Recherche de la Verité,” livre ii. chap. vii. p. 334, 7th ed., -1721. - -[68] The writer is indebted to Dr. Allen Thomson for reference to -the evidence contained in a note to Haller’s edition of Boerhaave’s -“Prælectiones Academicæ,” vol. v. pt ii. p. 497, published in 1744, -that Haller originally advocated epigenesis. - -[69] “Considérations sur les Corps organisés,” chap. x. - -[70] Bonnet had the courage of his opinions, and in the “Palingénésie -Philosophique,” part vi. chap, iv., he develops a hypothesis which -he terms “évolution naturelle;” and which, making allowance for his -peculiar views of the nature of generation, bears no small resemblance -to what is understood by “evolution” at the present day:— - -“Si la volonté divine a créé par un seul Acte l’Universalité des êtres, -d’où venoient ces plantes et ces animaux dont Moyse nous decrit la -Production au troisieme et au cinquieme jour du renouvellement de notre -monde? - -“Abuserois-je de la liberté de conjectures si je disois, que les -Plantes et les Animaux qui existent aujourd’hui sont parvenus par une -sorte d’evolution naturelle des Etres organisés qui peuplaient ce -premier Monde, sorti immédiatement des MAINS du CREATEUR?... - -“Ne supposons que trois révolutions. La Terre vient de sortir des MAINS -du CREATEUR. Des causes preparées par sa SAGESSE font développer de -toutes parts les Germes. Les Etres organisés commencent à jouir de -l’existence. Ils étoient probablement alors bien différens de ce qu’ils -sont aujourd’hui. Ils l’etoient autant que ce premier Monde différoit -de celui que nous habitons. Nous manquons de moyens pour juger de ces -dissemblances, et peut-être que le plus habile Naturaliste qui auroit -été placé dans ce premier Monde y auroit entièrement méconnu nos -Plantes et nos Animaux.” - -[71] “Ce mot (germe) ne désignera pas seulement un corps organisé -_réduit en petit_; il désignera encore toute espèce de _préformation -originelle dont un Tout organique pent résulter comme de son principe -immédiat_.”—“Palingénésie Philosophique,” part x. chap. ii. - -[72] “M. Cuvier considérant que tous les êtres organisés sont dérivés -de parens, et ne voyant dans la nature aucune force capable de produire -l’organisation, croyait à la pré-existence des germes; non pas à la -pré-existence d’un être tout formé, puisqu’il est bien évident que -ce n’est que par des développemens successifs que l’être acquiert -sa forme; mais, si l’on peut s’exprimer ainsi, à la pré-existence -du _radical de l’être_, radical qui existe avant que la série des -évolutions ne commence, et qui remonte certainement, suivant la belle -observation de Bonnet, à plusieurs generations.”—Laurillard, “Éloge de -Cuvier,” note 12. - -[73] “Histoire Naturelle,” tom. ii. ed. ii. 1750, p. 350. - -[74] _Ibid._ p. 351. - -[75] See particularly Buffon, _l.c._ p. 41. - -[76] “Exercitationes de Generatione.” Ex. 62, “Ovum esse primordium -commune omnibus animalibus.” - -[77] In some cases of sexless multiplication the germ is a -cell-aggregate—if we call germ only that which is already detached from -the parent organism. - -[78] Harvey, “Exercitationes de Generatione.” Ex. 45, “Quænam sit pulli -materia et quomodo fiat in Ovo.” - -[79] Not yet actually demonstrated in the case of phænogamous plants. - -[80] As Buffon has well said:—“L’idée de ramener l’explication de tous -les phénomènes à des principes mecaniques est assurement grande et -belle, ce pas est le plus hardi qu’on peut faire en philosophie, et -c’est Descartes qui l’a fait.”—_l.c._ p. 50. - -[81] “Principes de la Philosophie,” Troisième partie, § 45. - -[82] “Ethices,” Pars tertia, Præfatio. - -[83] “Système de la Nature.” “Essai sur la Formation des Corps -Organisés,” 1751, xiv. - -[84] “Considérations Philosophiques sur la gradation naturelle des -formes de l’être; ou les essais de la nature qui apprend à faire -l’homme,” 1768. - -[85] “Recherches sur les causes des principaux faits physiques,” par -J. B. Lamarck. Paris. Seconde année de la République. In the preface, -Lamarck says that the work was written in 1776, and presented to the -Academy in 1780; but it was not published before 1794, and, at that -time, it presumably expressed Lamarck’s mature views. It would be -interesting to know what brought about the change of opinion manifested -in the “Recherches sur l’organisation des corps vivants,” published -only seven years later. - -[86] See the “Historical Sketch” prefixed to the last edition of the -“Origin of Species.” - -[87] “First Principles” and “Principles of Biology,” 1860-1864. - -[88] “Generelle Morphologie,” 1866. - -[89] “Il s’agit donc de prouver que la série qui constitute l’échelle -animale réside essentiellement dans la distribution des masses -principales qui la composent et non dans celle des espèces ni même -toujours dans celle des genres.”—“Phil. Zoologique,” chap. v. - -[90] Philosophie Zoologique, première partie, chap. iii. - -[91] “Entwurf einer Darstellung der zwischen dem Embryozustande -der höheren Thiere und dem permanenten der niederen stattfindenden -Parallele,” “Beyträge zur Vergleichenden Anatomie,” Bd. ii. 1811. - -[92] “Origin of Species,” ed. 1, p. 457. - -[93] _Ibid._ p. 458. - -[94] “Origin of the Species,” p. 431. - -[95] “Origin of Species,” ed. 1, p. 463. - -[96] “Discours de la Méthode,” 6^e partie, Ed. Cousin, p. 193. - -[97] _Ibid._ pp. 193 and 211. - -[98] “De la Formation du Fœtus.” - -[99] “Theoria Generationis,” 1759. - -[100] “Anatomie générale,” i. p. liv. - - -THE END. - - -_Printed by_ R. & R. CLARK, _Edinburgh_. - - - - -MESSRS. MACMILLAN & CO.’S PUBLICATIONS. - - -BY THE SAME AUTHOR. - -Lay Sermons, Addresses, and Reviews. 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