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diff --git a/old/50767-0.txt b/old/50767-0.txt deleted file mode 100644 index d11db82..0000000 --- a/old/50767-0.txt +++ /dev/null @@ -1,7515 +0,0 @@ -Project Gutenberg's Life's Dawn on Earth, by John William, Sir Dawson - -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: Life's Dawn on Earth - Being the history of the oldest known fossil remains, and - their relations to geological time and to the development - of the animal kingdom - -Author: John William, Sir Dawson - -Release Date: December 25, 2015 [EBook #50767] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK LIFE'S DAWN ON EARTH *** - - - - -Produced by MWS, Tom Cosmas, Bryan Ness and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - - - - -Transcriber Notes - - -Text emphasis denoted as _Italics_. - - - - -[Illustration: - Plate I. - - From a Photo. by Henderson Vincent Brooke, Day & Son. Lith. - - - CAPE TRINITY ON THE SAGUENAY. - A CLIFF OF LAURENTIAN GNEISS. - - _Frontispiece_] - - - - - LIFE'S DAWN ON EARTH: - - BEING THE - - History of the Oldest Known Fossil Remains, - - AND - - THEIR RELATIONS TO GEOLOGICAL TIME - AND TO THE DEVELOPMENT OF - THE ANIMAL KINGDOM. - - - BY - - J. W. DAWSON, LL.D., F.R.S., F.G.S., Etc., - - PRINCIPAL AND VICE-CHANCELLOR OF M'GILL UNIVERSITY, MONTREAL; - AUTHOR OF - "ARCHAIA," "ACADIAN GEOLOGY," "THE STORY OF - THE EARTH AND MAN," ETC. - - - _SECOND THOUSAND._ - - - LONDON: - HODDER & STOUGHTON, - 27, PATERNOSTER ROW. - MDCCCLXXV. - - - - - Butler & Tanner, - The Selwood Printing Works, - Frome, and London. - - -To the Memory of - -SIR WILLIAM EDMOND LOGAN, - -LL.D., F.R.S., F.G.S., - -THIS WORK IS DEDICATED, - - -Not merely as a fitting acknowledgment of his long and successful -labours in the geology of those most ancient rocks, first named by -him Laurentian, and which have afforded the earliest known traces -of the beginning of life, but also as a tribute of sincere personal -esteem and regard to the memory of one who, while he attained to the -highest eminence as a student of nature, was also distinguished by his -patriotism and public spirit, by the simplicity and earnestness of his -character, and by the warmth of his friendships. - - - - -PREFACE. - - -An eminent German geologist has characterized the discovery of fossils -in the Laurentian rocks of Canada as "the opening of a new era in -geological science." Believing this to be no exaggeration, I have -felt it to be a duty incumbent on those who have been the apostles of -this new era, to make its significance as widely known as possible to -all who take any interest in scientific subjects, as well as to those -naturalists and geologists who may not have had their attention turned -to this special topic. - -The delivery of occasional lectures to popular audiences on this and -kindred subjects, has convinced me that the beginning of life in the -earth is a theme having attractions for all intelligent persons; -while the numerous inquiries on the part of scientific students with -reference to the fossils of the Eozoic age, show that the subject -is yet far from being familiar to their minds. I offer no apology -therefore for attempting to throw into the form of a book accessible -to general readers, what is known as to the dawn of life, and cannot -doubt that the present work will meet with at least as much acceptance -as that in which I recently endeavoured to picture the whole series of -the geological ages. - -I have to acknowledge my obligations to Sir W. E. Logan for most -of the Laurentian geology in the second chapter, and also for the -beautiful map which he has kindly had prepared at his own expense as -a contribution to the work. To Dr. Carpenter I am indebted for much -information as to foraminiferal structures, and to Dr. Hunt for the -chemistry of the subject. Mr. Selwyn, Director of the Geological -Survey of Canada, has kindly given me access to the materials in its -collections. Mr. Billings has contributed specimens and illustrations -of Palæozoic Protozoa; and Mr. Weston has aided greatly by the -preparation of slices for the microscope, and of photographs, as well -as by assistance in collecting. - - J. W. D. - - McGill College, Montreal. - _April, 1875._ - - - - -CONTENTS. - - - PAGE - - Chapter I. Introductory 1 - - Chapter II. The Laurentian System 7 - Notes:--Logan on Structure of Laurentian; Hunt - on Life in the Laurentian; Laurentian Graphite; - Western Laurentian; Metamorphism 24 - - Chapter III. The History of a Discovery 35 - Notes:--Logan on Discovery of Eozoon, and on - Additional Specimens 48 - - Chapter IV. What is Eozoon? 59 - Notes:--Original Description; Note by Dr. Carpenter; - Specimens from Long Lake; Additional - Structural Facts 76 - - Chapter V. Preservation of Eozoon 93 - Notes:--Hunt on Mineralogy of Eozoon; Silicified - Fossils in Silurian Limestones; Minerals - associated with Eozoon; Glauconites 115 - - Chapter VI. Contemporaries and Successors 127 - Notes:--On Stromatoporidæ; Localities of Eozoon 165 - - Chapter VII. Opponents and Objections 169 - Notes:--Objections and Replies; Hunt on - Chemical Objections; Reply by Dr. Carpenter 184 - - Chapter VIII. The Dawn-Animal as a Teacher in Science 207 - - Appendix 235 - - Index 237 - - - - -LIST OF ILLUSTRATIONS. - - -FULL PAGE ILLUSTRATIONS. - TO FACE - PAGE - - I. Cape Trinity, from a Photograph (_Frontispiece_). - - II. Map of the Laurentian Region on the River Ottawa 7 - - III. Weathered Specimen of Eozoon, from a Photograph 35 - - IV. Restoration of Eozoon 59 - - V. Nature-print of Eozoon 93 - - VI. Canals of Eozoon, Magnified, from Photographs 127 - - VII. Nature-print of Large Laminated Specimen 169 - - VIII. Eozoon With Chrysotile, etc. 207 - - -WOODCUTS. - - FIG. PAGE - - 1. General Section 9 - 2. Laurentian Hills 11 - 3. Section of Laurentian 13 - 4. Laurentian Map 16 - 5. Section at St. Pierre 22 - 6. Sketch of Rocks at St. Pierre 22 - 7. Eozoon from Burgess 36 - 8, 9. Eozoon from Calumet 39 - 10. Canals of Eozoon 41 - 11. Nummuline Wall 43 - 12. Amœba 60 - 13. Actinophrys 60 - 14. Entosolenia 62 - 15. Biloculina 62 - 16. Polystomella 62 - 17. Polymorphina 63 - 18. Archæospherinæ 67 - 19. Nummulites 73 - 20. Calcarina 73 - 21. Foraminiferal Rock-builders 75 - 21_a_. Casts of Cells of Eozoon 92 - 22. Modes of Mineralization 96 - 23. Silurian Organic Limestone 98 - 24. Wall of Eozoon Penetrated with Canals 98 - 25. Crinoid Infiltrated with Silicate 103 - 26. Shell Infiltrated with Silicate 104 - 27. Diagram of Proper Wall, etc. 106 - 28, 29. Casts of Canals 107 - 30. Eozoon from Tudor 111 - 31. Acervuline Variety of Eozoon 135 - 32, 33, 34. Archæospherinæ 137, 138 - 35. Annelid Burrows 140 - 36. Archæospherinæ 148 - 37. Eozoon Bavaricum 149 - 38, 39, 40. Archæocyathus 152, 153 - 41. Archæocyathus (Structure of) 154 - 42. Stromatopora 157 - 43. Stromatopora (Structure of) 158 - 44. Caunopora 159 - 45. Cœnostroma 160 - 46. Receptaculites 162 - 47, 48. Receptaculites (Structure of) 163 - 49. Laminæ of Eozoon 176 - - - - -THE DAWN OF LIFE. - - - - -CHAPTER I. - -INTRODUCTORY. - - -Every one has heard of, or ought to have heard of, _Eozoon Canadense_, -the Canadian Dawn-animal, the sole fossil of the ancient Laurentian -rocks of North America, the earliest known representative on our planet -of those wondrous powers of animal life which culminate and unite -themselves with the spirit-world in man himself. Yet few even of those -to whom the name is familiar, know how much it implies, and how strange -and wonderful is the story which can be evoked from this first-born of -old ocean. - -No one probably believes that animal life has been an eternal -succession of like forms of being. We are familiar with the idea that -in some way it was introduced; and most men now know, either from the -testimony of Genesis or geology, or of both, that the lower forms -of animal life were introduced first, and that these first living -creatures had their birth in the waters, which are still the prolific -mother of living things innumerable. Further, there is a general -impression that it would be the most appropriate way that the great -procession of animal existence should commence with the humblest types -known to us, and should march on in successive bands of gradually -increasing dignity and power, till man himself brings up the rear. - -Do we know the first animal? Can we name it, explain its structure, -and state its relations to its successors? Can we do this by inference -from the succeeding types of being; and if so, do our anticipations -agree with any actual reality disinterred from the earth's crust? If we -could do this, either by inference or actual discovery, how strange it -would be to know that we had before us even the remains of the first -creature that could feel or will, and could place itself in vital -relation with the great powers of inanimate nature. If we believe in a -Creator, we shall feel it a solemn thing to have access to the first -creature into which He breathed the breath of life. If we hold that all -things have been evolved from collision of dead forces, then the first -molecules of matter which took upon themselves the responsibility of -living, and, aiming at the enjoyment of happiness, subjected themselves -to the dread alternatives of pain and mortality, must surely evoke -from us that filial reverence which we owe to the authors of our own -being, if they do not involuntarily draw forth even a superstitious -adoration. The veneration of the old Egyptian for his sacred animals -would be a comparatively reasonable idolatry, if we could imagine any -of these animals to have been the first that emerged from the domain -of dead matter, and the first link in a reproductive chain of being -that produced all the population of the world. Independently of any -such hypotheses, all students of nature must regard with surpassing -interest the first bright streaks of light that break on the long reign -of primeval night and death, and presage the busy day of teeming animal -existence. - -No wonder then that geologists have long and earnestly groped in the -rocky archives of the earth in search of some record of this patriarch -of the animal kingdom. But after long and patient research, there still -remained a large residuum of the oldest rocks, destitute of all traces -of living beings, and designated by the hopeless name "Azoic,"--the -formations destitute of remains of life, the stony records of a -lifeless world. So the matter remained till the Laurentian rocks of -Canada, lying at the base of these old Azoic formations, afforded -forms believed to be of organic origin. The discovery was hailed -with enthusiasm by those who had been prepared by previous study to -receive it. It was regarded with feeble and not very intelligent faith -by many more, and was met with half-concealed or open scepticism by -others. It produced a copious crop of descriptive and controversial -literature, but for the most part technical, and confined to scientific -transactions and periodicals, read by very few except specialists. -Thus, few even of geological and biological students have clear ideas -of the real nature and mode of occurrence of these ancient organisms, -and of their relations to better known forms of life; while the crudest -and most inaccurate ideas have been current in lectures and popular -books, and even in text-books, although to the minds of those really -acquainted with the facts, all the disputed points have long ago been -satisfactorily settled, and the true nature and affinities of Eozoon -are distinctly and satisfactorily understood. - -This state of things has long ceased to be desirable in the interests -of science, since the settlement of the questions raised is in the -highest degree important to the history of life. We cannot, it is true, -affirm that Eozoon is in reality the long sought prototype of animal -existence; but it is for us at present the last organic foothold, on -which we can poise ourselves, that we may look back into the abyss -of the infinite past, and forward to the long and varied progress of -life in geological time. Its consideration, therefore, is certain, -if properly entered into, to be fruitful of interesting and valuable -thought, and to form the best possible introduction to the history of -life in connection with geology. - -It is for these reasons, and because I have been connected with this -great discovery from the first, and have for the last ten years given -to it an amount of labour and attention far greater than could be -adequately represented by short and technical papers, that I have -planned the present work. In it I propose to give a popular, yet -as far as possible accurate, account of all that is known of the -Dawn-animal of the Laurentian rocks of Canada. This will include, -firstly: a descriptive notice of the Laurentian formation itself. -Secondly: a history of the steps which led to the discovery and proper -interpretation of this ancient fossil. Thirdly: the description of -Eozoon, and the explanation of the manner in which its remains have -been preserved. Fourthly: inquiries as to forms of animal life, its -contemporaries and immediate successors, or allied to it by zoological -affinity. Fifthly: the objections which have been urged against its -organic nature. And sixthly: the summing up of the lessons in science -which it is fitted to teach. On these points, while I shall endeavour -to state the substance of all that has been previously published, I -shall bring forward many new facts illustrative of points hitherto more -or less obscure, and shall endeavour so to picture these in themselves -and their relations, as to give distinct and vivid impressions to the -reader. - -For the benefit of those who may not have access to the original -memoirs, or may not have time to consult them, I shall append to the -several chapters some of the technical details. These may be omitted by -the general reader; but will serve to make the work more complete and -useful as a book of reference. - -The only preparation necessary for the unscientific reader of this -work, will be some little knowledge of the division of geological time -into successive ages, as represented by the diagram of formations -appended to this chapter, and more full explanations may be obtained by -consulting any of the numerous elementary manuals on geology, or "The -Story of the Earth and Man," by the writer of the present work. - -TABULAR VIEW OF THE EARTH'S GEOLOGICAL HISTORY. - - _Animal Kingdom._ _Geological Periods._ _Vegetable Kingdom._ - - Age of Man. CENOZOIC, OR Modern. Age of Angiosperms - NEOZOIC, OR Post-Pliocene, and Palms. - TERTIARY or Pleistocene. - Pliocene. - Miocene. - Age of Mammals. Eocene. - - Age of Reptiles. MESOZOIC Cretaceous. Age of Cycads and - Jurassic. Pines. - Triassic. - - Age of Amphibians PALÆOZOIC Permian. Age of Acrogens - and Fishes. Carboniferous. and Gymnosperms. - Erian, or Devonian. - Age of Mollusks, Upper Silurian. - Corals, and Lower Silurian, or - Crustaceans. Siluro-Cambrian. - Cambrian or - Primordial. Age of Algæ. - - Age of Protozoa, EOZOIC Huronian. Beginning of Age - and dawn of Upper Laurentian. of Algæ. - Animal Life. Lower Laurentian. - -[Illustration: - Plate II. - -MAP SHEWING THE DISTRIBUTION OF THE LAURENTIAN LIMESTONES HOLDING EOZOON - IN THE COUNTIES OF OTTAWA & ARGENTEUIL. - -_Drawn by M. R. Barlow_ _Stanford's Geog. Estab^t. Charing Cross, London._ - - Reprinted with additions from the Report of the Geology of Canada, - by Sir W. Logan, F.R.S., 1863.] - - - - -CHAPTER II. - -THE LAURENTIAN ROCKS. - - -As we descend in depth and time into the earth's crust, after passing -through nearly all the vast series of strata constituting the monuments -of geological history, we at length reach the Eozoic or Laurentian -rocks, deepest and oldest of all the formations known to the geologist, -and more thoroughly altered or metamorphosed by heat and heated -moisture than any others. These rocks, at one time known as Azoic, -being supposed destitute of all remains of living things, but now more -properly Eozoic, are those in which the first bright streaks of the -dawn of life make their appearance.[A] - -[Footnote A: Dana has recently proposed the term "_Archæan_," on the -ground that some of these rocks are as yet unfossiliferous but as the -oldest known part of them contains fossils, there seems no need for -this new name.] - -The name Laurentian, given originally to the Canadian development of -these rocks by Sir William Logan, but now applied to them throughout -the world, is derived from a range of hills lying north of the -St. Lawrence valley, which the old French geographers named the -Laurentides. In these hills the harder rocks of this old formation -rise to considerable heights, and form the highlands separating the -St. Lawrence valley from the great plain fronting on Hudson's Bay -and the Arctic Sea. At first sight it may seem strange that rocks so -ancient should anywhere appear at the surface, especially on the tops -of hills; but this is a necessary result of the mode of formation of -our continents. The most ancient sediments deposited in the sea were -those first elevated into land, and first altered and hardened by heat. -Upheaved in the folding of the earth's crust into high and rugged -ridges, they have either remained uncovered with newer sediments, or -have had such as were deposited on them washed away; and being of a -hard and resisting nature, they have remained comparatively unworn when -rocks much more modern have been swept off by denuding agencies. - -But the exposure of the old Laurentian skeleton of mother earth is not -confined to the Laurentide Hills, though these have given the formation -its name. The same ancient rocks appear in the Adirondack mountains -of New York, and in the patches which at lower levels protrude from -beneath the newer formations along the American coast from Newfoundland -to Maryland. The older gneisses of Norway, Sweden, and the Hebrides, -of Bavaria and Bohemia, belong to the same age, and it is not unlikely -that similar rocks in many other parts of the old continent will be -found to be of as great antiquity. In no part of the world, however, -are the Laurentian rocks more extensively distributed or better -known than in North America; and to this as the grandest and most -instructive development of them, and that which first afforded organic -remains, we may more especially devote our attention. Their general -relations to the other formations of America may be learned from the -rough generalised section (fig. 1); in which the crumpled and contorted -Laurentian strata of Canada are seen to underlie unconformably the -comparatively flat Silurian beds, which are themselves among the oldest -monuments of the geological history of the earth. - -[Illustration: Fig. 1. _General Section, showing the Relations of -the Laurentian and Palæozoic Rocks in Canada._ (L.) Laurentian. (1.) -Cambrian, or Primordial. (2.) Lower Silurian. (3.) Upper Silurian. (4.) -Devonian and Carboniferous.] - -The Laurentian rocks, associated with another series only a little -younger, the Huronian, form a great belt of broken and hilly country, -extending from Labrador across the north of Canada to Lake Superior, -and thence bending northward to the Arctic Sea. Everywhere on the lower -St. Lawrence they appear as ranges of billowy rounded ridges on the -north side of the river; and as viewed from the water or the southern -shore, especially when sunset deepens their tints to blue and violet, -they present a grand and massive appearance, which, in the eye of -the geologist, who knows that they have endured the battles and the -storms of time longer than any other mountains, invests them with a -dignity which their mere elevation would fail to give. (Fig. 2.) In the -isolated mass of the Adirondacks, south of the Canadian frontier, they -rise to a still greater elevation, and form an imposing mountain group, -almost equal in height to their somewhat more modern rivals, the White -Mountains, which face them on the opposite side of Lake Champlain. - -The grandeur of the old Laurentian ranges is, however, best displayed -where they have been cut across by the great transverse gorge of the -Saguenay, and where the magnificent precipices, known as Capes Trinity -and Eternity, look down from their elevation of 1500 feet on a fiord, -which at their base is more than 100 fathoms deep (see frontispiece). -The name Eternity applied to such a mass is geologically scarcely a -misnomer, for it dates back to the very dawn of geological time, and is -of hoar antiquity in comparison with such upstart ranges as the Andes -and the Alps. - -[Illustration: Fig. 2. _Laurentian Hills opposite Kamouraska, Lower St. -Lawrence._ - -The islands in front are Primordial.] - -On a nearer acquaintance, the Laurentian country appears as a broken -and hilly upland and highland district, clad in its pristine state -with magnificent forests, but affording few attractions to the -agriculturist, except in the valleys, which follow the lines of its -softer beds, while it is a favourite region for the angler, the hunter, -and the lumberman. Many of the Laurentian townships of Canada are, -however, already extensively settled, and the traveller may pass -through a succession of more or less cultivated valleys, bounded by -rocks or wooded hills and crags, and diversified by running streams and -romantic lakes and ponds, constituting a country always picturesque -and often beautiful, and rearing a strong and hardy population. To -the geologist it presents in the main immensely thick beds of gneiss, -and similar metamorphic and crystalline rocks, contorted in the most -remarkable manner, so that if they could be flattened out they would -serve as a skin much too large for mother earth in her present state, -so much has she shrunk and wrinkled since those youthful days when the -Laurentian rocks were her outer covering. (Fig. 3.) - -The elaborate sections of Sir William Logan show that these old rocks -are divisible into two series, the Lower and Upper Laurentian; the -latter being the newer of the two, and perhaps separated from the -former by a long interval of time; but this Upper Laurentian being -probably itself older than the Huronian series, and this again older -than all the other stratified rocks. The Lower Laurentian, which -attains to a thickness of more than 20,000 feet, consists of stratified -granitic rocks or gneisses, of indurated sandstone or quartzite, of -mica and hornblende schist, and of crystalline limestones or marbles, -and iron ores, the whole interstratified with each other. The Upper -Laurentian, which is 10,000 feet thick at least, consists in part of -similar rocks, but associated with great beds of triclinic feldspar, -especially of that peculiar variety known as labradorite, or Labrador -feldspar, and which sometimes by its wonderful iridescent play of -colours becomes a beautiful ornamental stone. - -I cannot describe such rocks, but their names will tell something to -those who have any knowledge of the older crystalline materials of the -earth's crust. To those who have not, I would advise a visit to some -cliff on the lower St. Lawrence, or the Hebridean coasts, or the shore -of Norway, where the old hard crystalline and gnarled beds present -their sharp edges to the ever raging sea, and show their endless -alternations of various kinds and colours of strata often diversified -with veins and nests of crystalline minerals. He who has seen and -studied such a section of Laurentian rock cannot forget it. - -[Illustration: Fig. 3. _Section from Petite Nation Seigniory to St. -Jerome_ (60 miles). _After Sir W. E. Logan._ - -(_a, b._) Upper Laurentian. (_c._) Fourth gneiss. (_d´._) Third -limestone. (_d._) Third gneiss. (_e´._) Second limestone. (_x._) -Porphyry. (_y._) Granite.] - -All the constituents of the Laurentian series are in that state known -to geologists as metamorphic. They were once sandstones, clays, and -limestones, such as the sea now deposits, or such as form the common -plebeian rocks of everyday plains and hills and coast sections. Being -extremely old, however, they have been buried deep in the bowels of -the earth under the newer deposits, and hardened by the action of -pressure and of heat and heated water. Whether this heat was part -of that originally belonging to the earth when a molten mass, and -still existing in its interior after aqueous rocks had begun to form -on its surface, or whether it is a mere mechanical effect of the -intense compression which these rocks have suffered, may be a disputed -question; but the observations of Sorby and of Hunt (the former in -connection with the microscopic structure of rocks, and the latter -in connection with the chemical conditions of change) show that no -very excessive amount of heat would be required. These observations -and those of Daubrée indicate that crystallization like that of the -Laurentian rocks might take place at a temperature of not over 370° of -the centigrade thermometer. - -The study of those partial alterations which take place in the -vicinity of volcanic and older aqueous masses of rock confirms these -conclusions, so that we may be said to know the precise conditions -under which sediments may be hardened into crystalline rocks, while -the bedded character and the alternations of different layers in the -Laurentian rocks, as well as the indications of contemporary marine -life which they contain, show that they actually are such altered -sediments. (See Note D.) - -It is interesting to notice here that the Laurentian rocks thus -interpreted show that the oldest known portions of our continents were -formed in the waters. They are oceanic sediments deposited perhaps when -there was no dry land or very little, and that little unknown to us -except in so far as its debris may have entered into the composition -of the Laurentian rocks themselves. Thus the earliest condition of the -earth known to the geologist is one in which old ocean was already -dominant on its surface; and any previous condition when the surface -was heated, and the water constituted an abyss of vapours enveloping -its surface, or any still earlier condition in which the earth was -gaseous or vaporous, is a matter of mere inference, not of actual -observation. The formless and void chaos is a deduction of chemical and -physical principles, not a fact observed by the geologist. Still we -know, from the great dykes and masses of igneous or molten rock which -traverse the Laurentian beds, that even at that early period there were -deep-seated fires beneath the crust; and it is quite possible that -volcanic agencies then manifested themselves, not only with quite as -great intensity, but also in the same manner, as at subsequent times. -It is thus not unlikely that much of the land undergoing waste in the -earlier Laurentian time was of the same nature with recent volcanic -ejections, and that it formed groups of islands in an otherwise -boundless ocean. - -However this may be, the distribution and extent of these -pre-Laurentian lands is, and probably ever must be, unknown to us; for -it was only after the Laurentian rocks had been deposited, and after -the shrinkage of the earth's crust in subsequent times had bent and -contorted them, that the foundations of the continents were laid. The -rude sketch map of America given in fig. 4 will show this, and will -also show that the old Laurentian mountains mark out the future form of -the American continent. - -[Illustration: Fig. 4. _The Laurentian Nucleus of the American -Continent._] - -Rocks so highly altered as the Laurentian beds can scarcely be expected -to hold well characterized fossil remains, and those geologists who -entertained any hope that such remains might have been preserved, long -looked in vain for their actual discovery. Still, as astronomers have -suspected the existence of unknown planets from observing perturbations -not accounted for, and as voyagers have suspected the approach to -unknown regions by the appearance of floating wood or stray land birds, -anticipations of such discoveries have been entertained and expressed -from time to time. Lyell, Dana, and Sterry Hunt more especially, have -committed themselves to such speculations. The reasons assigned may be -stated thus:-- - -Assuming the Laurentian rocks to be altered sediments, they must, from -their great extent, have been deposited in the ocean; and if there had -been no living creatures in the waters, we have no reason to believe -that they would have consisted of anything more than such sandy and -muddy debris as may be washed away from wasting rocks originally of -igneous origin. But the Laurentian beds contain other materials than -these. No formations of any geological age include thicker or more -extensive limestones. One of the beds measured by the officers of the -Geological Survey, is stated to be 1500 feet in thickness, another is -1250 feet thick, and a third 750 feet; making an aggregate of 3500 -feet.[B] These beds may be traced, with more or less interruption, -for hundreds of miles. Whatever the origin of such limestones, it -is plain that they indicate causes equal in extent, and comparable -in power and duration, with those which have produced the greatest -limestones of the later geological periods. Now, in later formations, -limestone is usually an organic rock, accumulated by the slow gathering -from the sea-water, or its plants, of calcareous matter, by corals, -foraminifera, or shell-fish, and the deposition of their skeletons, -either entire or in fragments, in the sea-bottom. The most friable -chalk and the most crystalline limestones have alike been formed in -this way. We know of no reason why it should be different in the -Laurentian period. When, therefore, we find great and conformable -beds of limestone, such as those described by Sir William Logan in -the Laurentian of Canada, we naturally imagine a quiet sea-bottom, in -which multitudes of animals of humble organization were accumulating -limestone in their hard parts, and depositing this in gradually -increasing thickness from age to age. Any attempts to account otherwise -for these thick and greatly extended beds, regularly interstratified -with other deposits, have so far been failures, and have arisen either -from a want of comprehension of the nature and magnitude of the -appearances to be explained, or from the error of mistaking the true -bedded limestones for veins of calcareous spar. - -[Footnote B: Logan: _Geology of Canada_, p. 45.] - -The Laurentian rocks contain great quantities of carbon, in the form of -graphite or plumbago. This does not occur wholly, or even principally, -in veins or fissures, but in the substance of the limestone and gneiss, -and in regular layers. So abundant is it, that I have estimated the -amount of carbon in one division of the Lower Laurentian of the Ottawa -district at an aggregate thickness of not less than twenty to thirty -feet, an amount comparable with that in the true coal formation itself. -Now we know of no agency existing in present or in past geological -time capable of deoxidizing carbonic acid, and fixing its carbon as -an ingredient in permanent rocks, except vegetable life. Unless, -therefore, we suppose that there existed in the Laurentian age a vast -abundance of vegetation, either in the sea or on the land, we have no -means of explaining the Laurentian graphite. - -The Laurentian formation contains great beds of oxide of iron, -sometimes seventy feet in thickness. Here again we have an evidence of -organic action; for it is the deoxidizing power of vegetable matter -which has in all the later formations been the efficient cause in -producing bedded deposits of iron. This is the case in modern bog and -lake ores, in the clay iron-stones of the coal measures, and apparently -also in the great ore beds of the Silurian rocks. May not similar -causes have been at work in the Laurentian period? - -Any one of these reasons might, in itself, be held insufficient to -prove so great and, at first sight, unlikely a conclusion as that of -the existence of abundant animal and vegetable life in the Laurentian; -but the concurrence of the whole in a series of deposits unquestionably -marine, forms a chain of evidence so powerful that it might command -belief even if no fragment of any organic and living form or structure -had ever been recognised in these ancient rocks. - -Such was the condition of the matter until the existence of supposed -organic remains was announced by Sir W. Logan, at the American -Association for the Advancement of Science, in Springfield, in 1859; -and we may now proceed to narrate the manner of this discovery, and how -it has been followed up. - -Before doing so, however, let us visit Eozoon in one of its haunts -among the Laurentian Hills. One of the most noted repositories of its -remains is the great Grenville band of limestone (see section, fig. 3, -and map), the outcrop of which may be seen in our map of the country -near the Ottawa, twisting itself like a great serpent in the midst of -the gneissose rocks; and one of the most fruitful localities is at a -place called Côte St. Pierre on this band. Landing, as I did, with -Mr. Weston, of the Geological Survey, last autumn, at Papineauville, -we find ourselves on the Laurentian rocks, and pass over one of the -great bands of gneiss for about twelve miles, to the village of St. -André Avelin. On the road we see on either hand abrupt rocky ridges, -partially clad with forest, and sometimes showing on their flanks the -stratification of the gneiss in very distinct parallel bands, often -contorted, as if the rocks, when soft, had been wrung as a washer-woman -wrings clothes. Between the hills are little irregular valleys, from -which the wheat and oats have just been reaped, and the tall Indian -corn and yellow pumpkins are still standing in the fields. Where not -cultivated, the land is covered with a rich second growth of young -maples, birches, and oaks, among which still stand the stumps and tall -scathed trunks of enormous pines, which constituted the original -forest. Half way we cross the Nation River, a stream nearly as large as -the Tweed, flowing placidly between wooded banks, which are mirrored in -its surface; but in the distance we can hear the roar of its rapids, -dreaded by lumberers in their spring drivings of logs, and which we -were told swallowed up five poor fellows only a few months ago. Arrived -at St. André, we find a wider valley, the indication of the change to -the limestone band, and along this, with the gneiss hills still in view -on either hand, and often encroaching on the road, we drive for five -miles more to Côte St. Pierre. At this place the lowest depression of -the valley is occupied by a little pond, and, hard by, the limestone, -protected by a ridge of gneiss, rises in an abrupt wooded bank by -the roadside, and a little further forms a bare white promontory, -projecting into the fields. Here was Mr. Love's original excavation, -whence some of the greater blocks containing Eozoon were taken, and a -larger opening made by an enterprising American on a vein of fibrous -serpentine, yielding "rock cotton," for packing steam pistons and -similar purposes. (Figs. 5 and 6.) - -[Illustration: Fig. 5. _Attitude of Limestone at St. Pierre._ - -(_a._) Gneiss band in the Limestone. (_b._) Limestone with Eozoon. -(_c._) Diorite and Gneiss.] - -[Illustration: Fig. 6. _Gneiss and Limestone at St. Pierre._ - -(_a._) Limestone. (_b._) Gneiss and Diorite.] - -The limestone is here highly inclined and much contorted, and in all -the excavations a thickness of about 100 feet of it may be exposed. -It is white and crystalline, varying much however in coarseness in -different bands. It is in some layers pure and white, in others it -is traversed by many gray layers of gneissose and other matter, or -by irregular bands and nodules of pyroxene and serpentine, and it -contains subordinate beds of dolomite. In one layer only, and this -but a few feet thick, does the Eozoon occur in any abundance in a -perfect state, though fragments and imperfectly preserved specimens -abound in other parts of the bed. It is a great mistake to suppose -that it constitutes whole beds of rock in an uninterrupted mass. -Its true mode of occurrence is best seen on the weathered surfaces -of the rock, where the serpentinous specimens project in irregular -patches of various sizes, sometimes twisted by the contortion of the -beds, but often too small to suffer in this way. On such surfaces -the projecting patches of the fossil exhibit laminæ of serpentine so -precisely like the _Stromatoporæ_ of the Silurian rocks, that any -collector would pounce upon them at once as fossils. In some places -these small weathered specimens can be easily chipped off from the -crumbling surface of the limestone; and it is perhaps to be regretted -that they have not been more extensively shown to palæontologists, with -the cut slices which to many of them are so problematical. One of the -original specimens, brought from the Calumet, and now in the Museum -of the Geological Survey of Canada, was of this kind, and much finer -specimens from Côte St. Pierre are now in that collection and in my -own. A very fine example is represented, on a reduced scale, in Plate -III., which is taken from an original photograph.[C] In some of the -layers are found other and more minute fossils than Eozoon, and these, -together with its fragmental remains, as ingredients in the limestone, -will be discussed in the sequel. We may merely notice here that the -most abundant layer of Eozoon at this place, occurs near the base of -the great limestone band, and that the upper layers in so far as seen -are less rich in it. Further, there is no necessary connection between -Eozoon and the occurrence of serpentine, for there are many layers -full of bands and lenticular masses of that mineral without any Eozoon -except occasional fragments, while the fossil is sometimes partially -mineralized with pyroxene, dolomite, or common limestone. The section -in fig. 5 will serve to show the attitude of the limestone at this -place, while the more general section, fig. 3, taken from Sir William -Logan, shows its relation to the other Laurentian rocks, and the sketch -in fig. 6 shows its appearance as a feature on the surface of the -country. - -[Footnote C: By Mr. Weston, of the Geological Survey of Canada.] - - -NOTES TO CHAPTER II. - - -(A.) Sir William E. Logan on the Laurentian System. - -[_Journal of Geological Society of London_, February, 1865.] - - After stating the division of the Laurentian series into the two - great groups of the Upper and Lower Laurentian, Sir William goes on - to say:-- - - "The united thickness of these two groups in Canada cannot be less - than 30,000 feet, and probably much exceeds it. The Laurentian of - the west of Scotland, according to Sir Roderick Murchison, also - attains a great thickness. In that region the Upper Laurentian or - Labrador series, has not yet been separately recognised; but from - Mr. McCulloch's description, as well as from the specimens collected - by him, and now in the Museum of the Geological Society of London, - it can scarcely be doubted that the Labrador series occurs in Skye. - The labradorite and hypersthene rocks from that island are identical - with those of the Labrador series in Canada and New York, and unlike - those of any formation at any other known horizon. This resemblance - did not escape the notice of Emmons, who, in his description of the - Adirondack Mountains, referred these rocks to the hypersthene rock - of McCulloch, although these observers, on the opposite sides of - the Atlantic, looked upon them as unstratified. In the _Canadian - Naturalist_ for 1862, Mr. Thomas Macfarlane, for some time resident - in Norway, and now in Canada, drew attention to the striking - resemblance between the Norwegian primitive gneiss formation, as - described by Naumann and Keilhau, and observed by himself, and the - Laurentian, including the Labrador group; and the equally remarkable - similarity of the lower part of the primitive slate formation - to the Huronian series, which is a third Canadian group. These - primitive series attain a great thickness in the north of Europe, and - constitute the main features of Scandinavian geology. - - "In Bavaria and Bohemia there is an ancient gneissic series. After - the labours in Scotland, by which he was the first to establish a - Laurentian equivalent in the British Isles, Sir Roderick Murchison, - turning his attention to this central European mass, placed it on the - same horizon. These rocks, underlying Barrande's Primordial zone, - with a great development of intervening clay-slate, extend southward - in breadth to the banks of the Danube, with a prevailing dip towards - the Silurian strata. They had previously been studied by Gümbel and - Crejci, who divided them into an older reddish gneiss and a newer - grey gneiss. But, on the Danube, the mass which is furthest removed - from the Silurian rocks being a grey gneiss, Gümbel and Crejci - account for its presence by an inverted fold in the strata; while - Sir Roderick places this at the base, and regards the whole as a - single series, in the normal fundamental position of the Laurentian - of Scotland and of Canada. Considering the colossal thickness given - to the series (90,000 feet), it remains to be seen whether it may - not include both the Lower and Upper Laurentian, and possibly, in - addition, the Huronian. - - "This third Canadian group (the Huronian) has been shown by my - colleague, Mr. Murray, to be about 18,000 feet thick, and to consist - chiefly of quartzites, slate-conglomerates, diorites, and limestones. - The horizontal strata which form the base of the Lower Silurian in - western Canada, rest upon the upturned edges of the Huronian series; - which, in its turn, unconformably overlies the Lower Laurentian. The - Huronian is believed to be more recent than the Upper Laurentian - series, although the two formations have never yet been seen in - contact. - - "The united thickness of these three great series may possibly - far surpass that of all the succeeding rocks from the base of the - Palæozoic series to the present time. We are thus carried back to a - period so far remote, that the appearance of the so-called Primordial - fauna may by some be considered a comparatively modern event. We, - however, find that, even during the Laurentian period, the same - chemical and mechanical processes which have ever since been at - work disintegrating and reconstructing the earth's crust were in - operation as now. In the conglomerates of the Huronian series there - are enclosed boulders derived from the Laurentian, which seem to show - that the parent rock was altered to its present crystalline condition - before the deposit of the newer formation; while interstratified with - the Laurentian limestones there are beds of conglomerate, the pebbles - of which are themselves rolled fragments of a still older laminated - sand-rock, and the formation of these beds leads us still further - into the past. - - "In both the Upper and Lower Laurentian series there are several - zones of limestone, each of sufficient volume to constitute an - independent formation. Of these calcareous masses it has been - ascertained that three, at least, belong to the Lower Laurentian. But - as we do not as yet know with certainty either the base or the summit - of this series, these three may be conformably followed by many more. - Although the Lower and Upper Laurentian rocks spread over more than - 200,000 square miles in Canada, only about 1500 square miles have yet - been fully and connectedly examined in any one district, and it is - still impossible to say whether the numerous exposures of Laurentian - limestone met with in other parts of the province are equivalent to - any of the three zones, or whether they overlie or underlie them all." - - -(B.) Dr. Sterry Hunt on the Probable Existence of Life in the -Laurentian Period. - - Dr. Hunt's views on this subject were expressed in the _American - Journal of Science_, [2], vol. xxxi., p. 395. From this article, - written in 1861, after the announcement of the existence of laminated - forms supposed to be organic in the Laurentian, by Sir W. E. Logan, - but before their structure and affinities had been ascertained, I - quote the following sentences:-- - - "We see in the Laurentian series beds and veins of metallic - sulphurets, precisely as in more recent formations; and the extensive - beds of iron ore, hundreds of feet thick, which abound in that - ancient system, correspond not only to great volumes of strata - deprived of that metal, but, as we may suppose, to organic matters - which, but for the then great diffusion of iron-oxyd in conditions - favourable for their oxidation, might have formed deposits of mineral - carbon far more extensive than those beds of plumbago which we - actually meet in the Laurentian strata. All these conditions lead us - then to conclude the existence of an abundant vegetation during the - Laurentian period." - - -(C.) The Graphite of the Laurentian. - - The following is from a paper by the author, in the _Journal of the - Geological Society_, for February, 1870:-- - - "The graphite of the Laurentian of Canada occurs both in beds and in - veins, and in such a manner as to show that its origin and deposition - are contemporaneous with those of the containing rock. Sir William - Logan states[D] that 'the deposits of plumbago generally occur in the - limestones or in their immediate vicinity, and granular varieties - of the rock often contain large crystalline plates of plumbago. At - other times this mineral is so finely disseminated as to give a - bluish-gray colour to the limestone, and the distribution of bands - thus coloured, seems to mark the stratification of the rock.' He - further states:--'The plumbago is not confined to the limestones; - large crystalline scales of it are occasionally disseminated in - pyroxene rock or pyrallolite, and sometimes in quartzite and in - feldspathic rocks, or even in magnetic oxide of iron.' In addition - to these bedded forms, there are also true veins in which graphite - occurs associated with calcite, quartz, orthoclase, or pyroxene, - and either in disseminated scales, in detached masses, or in - bands or layers 'separated from each other and from the wall rock - by feldspar, pyroxene, and quartz.' Dr. Hunt also mentions the - occurrence of finely granular varieties, and of that peculiarly - waved and corrugated variety simulating fossil wood, though really a - mere form of laminated structure, which also occurs at Warrensburgh, - New York, and at the Marinski mine in Siberia. Many of the veins - are not true fissures, but rather constitute a network of shrinkage - cracks or segregation veins traversing in countless numbers the - containing rock, and most irregular in their dimensions, so that - they often resemble strings of nodular masses. It has been supposed - that the graphite of the veins was originally introduced as a liquid - hydrocarbon. Dr. Hunt, however, regards it as possible that it - may have been in a state of aqueous solution;[E] but in whatever - way introduced, the character of the veins indicates that in the - case of the greater number of them the carbonaceous material must - have been derived from the bedded rocks traversed by these veins, - while there can be no doubt that the graphite found in the beds has - been deposited along with the calcareous matter or muddy and sandy - sediment of which these beds were originally composed. - -[Footnote D: _Geology of Canada_, 1863.] - -[Footnote E: _Report of the Geological Survey of Canada_, 1866.] - - "The quantity of graphite in the Lower Laurentian series is enormous. - In a recent visit to the township of Buckingham, on the Ottawa - River, I examined a band of limestone believed to be a continuation - of that described by Sir W. E. Logan as the Green Lake Limestone. - It was estimated to amount, with some thin interstratified bands - of gneiss, to a thickness of 600 feet or more, and was found to - be filled with disseminated crystals of graphite and veins of the - mineral to such an extent as to constitute in some places one-fourth - of the whole; and making every allowance for the poorer portions, - this band cannot contain in all a less vertical thickness of pure - graphite than from twenty to thirty feet. In the adjoining township - of Lochaber Sir W. E. Logan notices a band from twenty-five to thirty - feet thick, reticulated with graphite veins to such an extent as - to be mined with profit for the mineral. At another place in the - same district a bed of graphite from ten to twelve feet thick, and - yielding twenty per cent. of the pure material, is worked. When it - is considered that graphite occurs in similar abundance at several - other horizons, in beds of limestone which have been ascertained by - Sir W. E. Logan to have an aggregate thickness of 3500 feet, it is - scarcely an exaggeration to maintain that the quantity of carbon in - the Laurentian is equal to that in similar areas of the Carboniferous - system. It is also to be observed that an immense area in Canada - appears to be occupied by these graphitic and Eozoon limestones, and - that rich graphitic deposits exist in the continuation of this system - in the State of New York, while in rocks believed to be of this age - near St. John, New Brunswick, there is a very thick bed of graphitic - limestone, and associated with it three regular beds of graphite, - having an aggregate thickness of about five feet.[F] - -[Footnote F: Matthew, in _Quart. Journ. Geol. Soc._, vol. xxi., p. 423. -_Acadian Geology_, p. 662.] - - "It may fairly be assumed that in the present world and in those - geological periods with whose organic remains we are more familiar - than with those of the Laurentian, there is no other source of - unoxidized carbon in rocks than that furnished by organic matter, - and that this has obtained its carbon in all cases, in the first - instance, from the deoxidation of carbonic acid by living plants. No - other source of carbon can, I believe, be imagined in the Laurentian - period. We may, however, suppose either that the graphitic matter - of the Laurentian has been accumulated in beds like those of coal, - or that it has consisted of diffused bituminous matter similar to - that in more modern bituminous shales and bituminous and oil-bearing - limestones. The beds of graphite near St. John, some of those in the - gneiss at Ticonderoga in New York, and at Lochaber and Buckingham - and elsewhere in Canada, are so pure and regular that one might - fairly compare them with the graphitic coal of Rhode Island. These - instances, however, are exceptional, and the greater part of the - disseminated and vein graphite might rather be compared in its mode - of occurrence to the bituminous matter in bituminous shales and - limestones. - - "We may compare the disseminated graphite to that which we find in - those districts of Canada in which Silurian and Devonian bituminous - shales and limestones have been metamorphosed and converted into - graphitic rocks not dissimilar to those in the less altered portions - of the Laurentian.[G] In like manner it seems probable that the - numerous reticulating veins of graphite may have been formed by - the segregation of bituminous matter into fissures and planes of - least resistance, in the manner in which such veins occur in modern - bituminous limestones and shales. Such bituminous veins occur in - the Lower Carboniferous limestone and shale of Dorchester and - Hillsborough, New Brunswick, with an arrangement very similar to that - of the veins of graphite; and in the Quebec rocks of Point Levi, - veins attaining to a thickness of more than a foot, are filled with a - coaly matter having a transverse columnar structure, and regarded by - Logan and Hunt as an altered bitumen. These palæozoic analogies would - lead us to infer that the larger part of the Laurentian graphite - falls under the second class of deposits above mentioned, and that, - if of vegetable origin, the organic matter must have been thoroughly - disintegrated and bituminized before it was changed into graphite. - This would also give a probability that the vegetation implied was - aquatic, or at least that it was accumulated under water. - -[Footnote G: Granby, Melbourne, Owl's Head, etc., _Geology of Canada_, -1863, p. 599.] - - "Dr. Hunt has, however, observed an indication of terrestrial - vegetation, or at least of subaërial decay, in the great beds of - Laurentian iron ore. These, if formed in the same manner as more - modern deposits of this kind, would imply the reducing and solvent - action of substances produced in the decay of plants. In this case - such great ore beds as that of Hull, on the Ottawa, seventy feet - thick, or that near Newborough, 200 feet thick,[H] must represent - a corresponding quantity of vegetable matter which has totally - disappeared. It may be added that similar demands on vegetable matter - as a deoxidizing agent are made by the beds and veins of metallic - sulphides of the Laurentian, though some of the latter are no doubt - of later date than the Laurentian rocks themselves. - -[Footnote H: _Geology of Canada_, 1863.] - - "It would be very desirable to confirm such conclusions as those - above deduced by the evidence of actual microscopic structure. It is - to be observed, however, that when, in more modern sediments, algæ - have been converted into bituminous matter, we cannot ordinarily - obtain any structural evidence of the origin of such bitumen, and in - the graphitic slates and limestones derived from the metamorphosis of - such rocks no organic structure remains. It is true that, in certain - bituminous shales and limestones of the Silurian system, shreds of - organic tissue can sometimes be detected, and in some cases, as in - the Lower Silurian limestone of the La Cloche mountains in Canada, - the pores of brachiopodous shells and the cells of corals have been - penetrated by black bituminous matter, forming what may be regarded - as natural injections, sometimes of much beauty. In correspondence - with this, while in some Laurentian graphitic rocks, as, for - instance, in the compact graphite of Clarendon, the carbon presents - a curdled appearance due to segregation, and precisely similar to - that of the bitumen in more modern bituminous rocks, I can detect in - the graphitic limestones occasional fibrous structures which may be - remains of plants, and in some specimens vermicular lines, which I - believe to be tubes of Eozoon penetrated by matter once bituminous, - but now in the state of graphite. - - "When palæozoic land-plants have been converted into graphite, - they sometimes perfectly retain their structure. Mineral charcoal, - with structure, exists in the graphitic coal of Rhode Island. The - fronds of ferns, with their minutest veins perfect, are preserved - in the Devonian shales of St. John, in the state of graphite; and - in the same formation there are trunks of Conifers (_Dadoxylon - ouangondianum_) in which the material of the cell-walls has been - converted into graphite, while their cavities have been filled with - calcareous spar and quartz, the finest structures being preserved - quite as well as in comparatively unaltered specimens from the - coal-formation.[I] No structures so perfect have as yet been detected - in the Laurentian, though in the largest of the three graphitic beds - at St. John there appear to be fibrous structures which I believe may - indicate the existence of land-plants. This graphite is composed of - contorted and slickensided laminæ, much like those of some bituminous - shales and coarse coals; and in these there are occasional small - pyritous masses which show hollow carbonaceous fibres, in some cases - presenting obscure indications of lateral pores. I regard these - indications, however, as uncertain; and it is not as yet fully - ascertained that these beds at St. John are on the same geological - horizon with the Lower Laurentian of Canada, though they certainly - underlie the Primordial series of the Acadian group, and are - separated from it by beds having the character of the Huronian. - -[Footnote I: _Acadian Geology_, p. 535. In calcified specimens the -structures remain in the graphite after decalcification by an acid.] - - "There is thus no absolute impossibility that distinct organic - tissues may be found in the Laurentian graphite, if formed from - land-plants, more especially if any plants existed at that time - having true woody or vascular tissues; but it cannot with certainty - be affirmed that such tissues have been found. It is possible, - however, that in the Laurentian period the vegetation of the land may - have consisted wholly of cellular plants, as, for example, mosses and - lichens; and if so, there would be comparatively little hope of the - distinct preservation of their forms or tissues, or of our being able - to distinguish the remains of land-plants from those of Algæ. - - "We may sum up these facts and considerations in the following - statements:--First, that somewhat obscure traces of organic structure - can be detected in the Laurentian graphite; secondly, that the - general arrangement and microscopic structure of the substance - corresponds with that of the carbonaceous and bituminous matters - in marine formations of more modern date; thirdly, that if the - Laurentian graphite has been derived from vegetable matter, it has - only undergone a metamorphosis similar in kind to that which organic - matter in metamorphosed sediment of later age has experienced; - fourthly, that the association of the graphitic matter with organic - limestone, beds of iron ore, and metallic sulphides, greatly - strengthens the probability of its vegetable origin; fifthly, that - when we consider the immense thickness and extent of the Eozoonal - and graphitic limestones and iron ore deposits of the Laurentian, if - we admit the organic origin of the limestone and graphite, we must - be prepared to believe that the life of that early period, though it - may have existed under low forms, was most copiously developed, and - that it equalled, perhaps surpassed, in its results, in the way of - geological accumulation, that of any subsequent period." - - -(D.) Western and other Laurentian Rocks, etc. - - In the map of the Laurentian nucleus of America (fig. 4,) I have - not inserted the Laurentian rocks believed to exist in the Rocky - Mountains and other western ranges. Their distribution is at present - uncertain, as well as the date of their elevation. They may indicate - an old line of Laurentian fracture or wrinkling, parallel to the west - coast, and defining its direction. In the map there should be a patch - of Laurentian in the north of Newfoundland, and it should be wider at - the west end of lake Superior. - - Full details as to the Laurentian rocks of Canada and sectional - lists of their beds will be found in the _Reports of the Geological - Survey_, and Dr. Hunt has discussed very fully their chemical - characters and metamorphism in his _Chemical and Geological Essays_. - The recent reports of Hitchcock on New Hampshire, and Hayden on - the Western Territories, contain some new facts of interest. - The former recognises in the White Mountain region a series of - gneisses and other altered rocks of Lower Laurentian age, and, - resting unconformably on these, others corresponding to the Upper - Laurentian; while above the latter are other pre-silurian formations - corresponding to the Huronian and probably to the Montalban series of - Hunt. These facts confirm Logan's results in Canada; and Hitchcock - finds many reasons to believe in the existence of life at the time of - the deposition of these old rocks. Hayden's report describes granitic - and gneissose rocks, probably of Laurentian age, as appearing over - great areas in Colorado, Arizona, Utah, and Nevada--showing the - existence of this old metamorphic floor over vast regions of Western - America. - - The metamorphism of these rocks does not imply any change of - their constituent elements, or interference with their bedded - arrangement. It consists in the alteration of the sediments by merely - molecular changes re-arranging their particles so as to render them - crystalline, or by chemical reactions producing new combinations of - their elements. Experiment shows that the action of heat, pressure, - and waters containing alkaline carbonates and silicates, would - produce such changes. The amount and character of change would depend - on the composition of the sediment, the heat applied, the substances - in solution in the water, and the lapse of time. (See _Hunt's - Essays_, p. 24.) - -[Illustration: - Plate III. - - From a Photo by Weston. Vincent Brooks, Day & Son, Lith. - - WEATHERED SPECIMEN OF EOZOON CANADENSE. - (ONE-HALF NATURAL SIZE.) - - _To face Chap. 3_] - - - - -CHAPTER III. - -THE HISTORY OF A DISCOVERY. - - -It is a trite remark that most discoveries are made, not by one -person, but by the joint exertions of many, and that they have their -preparations made often long before they actually appear. In this -case the stable foundations were laid, years before the discovery -of Eozoon, by the careful surveys made by Sir William Logan and his -assistants, and the chemical examination of the rocks and minerals -by Dr. Sterry Hunt. On the other hand, Dr. Carpenter and others in -England were examining the structure of the shells of the humbler -inhabitants of the modern ocean, and the manner in which the pores of -their skeletons become infiltrated with mineral matter when deposited -in the sea-bottom. These laborious and apparently dissimilar branches -of scientific inquiry were destined to be united by a series of happy -discoveries, made not fortuitously but by painstaking and intelligent -observers. The discovery of the most ancient fossil was thus not the -chance picking up of a rare and curious specimen. It was not likely -to be found in this way; and if so found, it would have remained -unnoticed and of no scientific value, but for the accumulated stores of -zoological and palæontological knowledge, and the surveys previously -made, whereby the age and distribution of the Laurentian rocks and -the chemical conditions of their deposition and metamorphism were -ascertained. - -[Illustration: Fig. 7. _Eozoon mineralized by Loganite and Dolomite._ - -(Collected by Dr. Wilson, of Perth.)] - -The first specimens of Eozoon ever procured, in so far as known, were -collected at Burgess in Ontario by a veteran Canadian mineralogist, -Dr. Wilson of Perth, and were sent to Sir William Logan as mineral -specimens. Their chief interest at that time lay in the fact that -certain laminæ of a dark green mineral present in the specimens were -found, on analysis by Dr. Hunt, to be composed of a new hydrous -silicate, allied to serpentine, and which he named loganite: one of -these specimens is represented in fig. 7. The form of this mineral was -not suspected to be of organic origin. Some years after, in 1858, other -specimens, differently mineralized with the minerals serpentine and -pyroxene, were found by Mr. J. McMullen, an explorer in the service -of the Geological Survey, in the limestone of the Grand Calumet on -the River Ottawa. These seem to have at once struck Sir W. E. Logan -as resembling the Silurian fossils known as _Stromatopora_, and he -showed them to Mr. Billings, the palæontologist of the survey, and to -the writer, with this suggestion, confirming it with the sagacious -consideration that inasmuch as the Ottawa and Burgess specimens were -mineralized by different substances, yet were alike in form, there was -little probability that they were merely mineral or concretionary. Mr. -Billings was naturally unwilling to risk his reputation in affirming -the organic nature of such specimens; and my own suggestion was that -they should be sliced, and examined microscopically, and that if -fossils, as they presented merely concentric laminæ and no cells, -they would probably prove to be protozoa rather than corals. A few -slices were accordingly made, but no definite structure could be -detected. Nevertheless Sir William Logan took some of the specimens to -the meeting of the American Association at Springfield, in 1859, and -exhibited them as possibly Laurentian fossils; but the announcement was -evidently received with some incredulity. In 1862 they were exhibited -by Sir William to some geological friends in London, but he remarks -that "few seemed disposed to believe in their organic character, with -the exception of my friend Professor Ramsay." In 1863 the General -Report of the Geological Survey, summing up its work to that time, -was published, under the name of the _Geology of Canada_, and in this, -at page 49, will be found two figures of one of the Calumet specimens, -here reproduced, and which, though unaccompanied with any specific -name or technical description, were referred to as probably Laurentian -fossils. (Figs. 8 and 9.) - -About this time Dr. Hunt happened to mention to me, in connection with -a paper on the mineralization of fossils which he was preparing, that -he proposed to notice the mode of preservation of certain fossil woods -and other things with which I was familiar, and that he would show me -the paper in proof, in order that he might have any suggestions that -occurred to me. On reading it, I observed, among other things, that -he alluded to the supposed Laurentian fossils, under the impression -that the organic part was represented by the serpentine or loganite, -and that the calcareous matter was the filling of the chambers. I took -exception to this, stating that though in the slices before examined -no structure was apparent, still my impression was that the calcareous -matter was the fossil, and the serpentine or loganite the filling. He -said--"In that case, would it not be well to re-examine the specimens, -and to try to discover which view is correct?" He mentioned at the same -time that Sir William had recently shown him some new and beautiful -specimens collected by Mr. Lowe, one of the explorers on the staff of -the Survey, from a third locality, at Grenville, on the Ottawa. It was -supposed that these might throw further light on the subject; and -accordingly Dr. Hunt suggested to Sir William to have additional slices -of these new specimens made by Mr. Weston, of the Survey, whose skill -as a preparer of these and other fossils has often done good service to -science. A few days thereafter, some slices were sent to me, and were -at once put under the microscope. I was delighted to find in one of the -first specimens examined a beautiful group of tubuli penetrating one of -the calcite layers. Here was evidence, not only that the calcite layers -represented the true skeleton of the fossil, but also of its affinities -with the Foraminifera, whose tubulated supplemental skeleton, as -described and figured by Dr. Carpenter, and represented in specimens -in my collection presented by him, was evidently of the same type with -that preserved in the canals of these ancient fossils. Fig. 10 is an -accurate representation of the first seen group of canals penetrated by -serpentine. - -[Illustration: Fig. 8. _Weathered Specimen of Eozoon from the Calumet._ - -(Collected by Mr. McMullen.)] - -[Illustration: Fig. 9. _Cross Section of the Specimen represented in -Fig. 8._ - -The dark parts are the laminæ of calcareous matter converging to the -outer surface.] - -On showing the structures discovered to Sir William Logan, he entered -into the matter with enthusiasm, and had a great number of slices and -afterwards of decalcified specimens prepared, which were placed in my -hands for examination. - -Feeling that the discovery was most important, but that it would be -met with determined scepticism by a great many geologists, I was -not content with examining the typical specimens of Eozoon, but had -slices prepared of every variety of Laurentian limestone, of altered -limestones from the Primordial and Silurian, and of serpentine -marbles of all the varieties furnished by our collections. These were -examined with ordinary and polarized light, and with every variety -of illumination. Dr. Hunt, on his part, undertook the chemical -investigation of the various associated minerals. An extensive series -of notes and camera tracings were made of all the appearances observed; -and of some of the more important structures beautiful drawings -were executed by the late Mr. H. S. Smith, the then palæontological -draughtsman of the Survey. The result of the whole investigation was a -firm conviction that the structure was organic and foraminiferal, and -that it could be distinguished from any merely mineral or crystalline -forms occurring in these or other limestones. - -[Illustration: Fig. 10. _Group of Canals in the Supplemental Skeleton -of Eozoon._ - -Taken from the specimen in which they were first recognised. -Magnified.] - -At this stage of the matter, and after exhibiting to Sir William all -the characteristic appearances in comparison with such concretionary, -dendritic, and crystalline structures as most resembled them, and also -with the structure of recent and fossil Foraminifera, I suggested that -the further prosecution of the matter should be handed over to Mr. -Billings, as palæontologist of the Survey, and as our highest authority -on the fossils of the older rocks. I was engaged in other researches, -and knew that no little labour must be devoted to the work and to its -publication, and that some controversy might be expected. Mr. Billings, -however, with his characteristic caution and modesty, declined. His -hands, he said, were full of other work, and he had not specially -studied the microscopic appearances of Foraminifera or of mineral -substances. It was finally arranged that I should prepare a description -of the fossil, which Sir William would take to London, along with Dr. -Hunt's notes, the more important specimens, and lists of the structures -observed in each. Sir William was to submit the manuscript and -specimens to Dr. Carpenter, or failing him to Prof. T. Rupert Jones, in -the hope that these eminent authorities would confirm our conclusions, -and bring forward new facts which I might have overlooked or been -ignorant of. Sir William saw both gentlemen, who gave their testimony -in favour of the organic and foraminiferal character of the specimens; -and Dr. Carpenter in particular gave much attention to the subject, and -worked out the structure of the primary cell-wall, which I had not -observed previously through a curious accident as to specimens.[J] Mr. -Lowe had been sent back to the Ottawa to explore, and just before Sir -William's departure had sent in some specimens from a new locality at -Petite Nation, similar in general appearance to those from Grenville, -which Sir William took with him unsliced to England. These showed in -a perfect manner the tubuli of the primary cell-wall, which I had in -vain tried to resolve in the Grenville specimens, and which I did -not see until after it had been detected by Dr. Carpenter in London. -Dr. Carpenter thus contributed in a very important manner to the -perfecting of the investigations begun in Canada, and on him has fallen -the greater part of their illustration and defence,[K] in so far as -Great Britain is concerned. Fig. 11, taken from one of Dr. Carpenter's -papers, shows the tubulated primitive wall as described by him. - -[Footnote J: In papers by Dr. Carpenter, subsequently referred to. -Prof. Jones published an able exposition of the facts in the _Popular -Science Monthly_.] - -[Footnote K: In _Quarterly Journal of Geological Society_, vol. xxii.; -_Proc. Royal Society_, vol. xv.; _Intellectual Observer_, 1865. _Annals -and Magazine of Natural History_, 1874; and other papers and notices.] - -[Illustration: Fig. 11. _Portion of Eozoon magnified 100 diameters, -showing the original Cell-wall with Tubulation, and the Supplemental -Skeleton with Canals._ (_After Carpenter._) - -(_a._) Original tubulated wall or "Nummuline layer," more magnified in -fig. 2. (_b, c._) "Intermediate skeleton," with canals.] - -The immediate result was a composite paper in the _Proceedings of the -Geological Society_, by Sir W. E. Logan, Dr. Carpenter, Dr. Hunt, and -myself, in which the geology, palæontology, and mineralogy of _Eozoon -Canadense_ and its containing rocks were first given to the world.[L] -It cannot be wondered at that when geologists and palæontologists were -thus required to believe in the existence of organic remains in rocks -regarded as altogether Azoic and hopelessly barren of fossils, and -to carry back the dawn of life as far before those Primordial rocks, -which were supposed to contain its first traces, as these are before -the middle period of the earth's life history, some hesitation should -be felt. Further, the accurate appreciation of the evidence for such a -fossil as Eozoon required an amount of knowledge of minerals, of the -more humble types of animals, and of the conditions of mineralization -of organic remains, possessed by few even of professional geologists. -Thus Eozoon has met with some negative scepticism and a little positive -opposition,--though the latter has been small in amount, when we -consider the novel and startling character of the facts adduced. - -[Footnote L: _Journal Geological Society_, February, 1865.] - -"The united thickness," says Sir William Logan, "of these three great -series, the Lower and Upper Laurentian and Huronian, may possibly far -surpass that of all succeeding rocks, from the base of the Palæozoic -to the present time. We are thus carried back to a period so far -remote that the appearance of the so-called Primordial fauna may -be considered a comparatively modern event." So great a revolution -of thought, and this based on one fossil, of a character little -recognisable by geologists generally, might well tax the faith of a -class of men usually regarded as somewhat faithless and sceptical. Yet -this new extension of life has been generally received, and has found -its way into text-books and popular treatises. Its opponents have -been under the necessity of inventing the most strange and incredible -pseudomorphoses of mineral substances to account for the facts; and -evidently hold out rather in the spirit of adhesion to a lost cause -than with any hope of ultimate success. As might have been expected, -after the publication of the original paper, other facts developed -themselves. Mr. Vennor found other and scarcely altered specimens in -the Upper Laurentian or Huronian of Tudor. Gümbel recognised the -organism in Laurentian Rocks in Bavaria and elsewhere in Europe, and -discovered a new species in the Huronian of Bavaria.[M] Eozoon was -recognised in Laurentian limestones in Massachusetts[N] and New York, -and there has been a rapid growth of new facts increasing our knowledge -of Foraminifera of similar types in the succeeding Palæozoic rocks. -Special interest attaches to the discovery by Mr. Vennor of specimens -of Eozoon contained in a dark micaceous limestone at Tudor, in Ontario, -and really as little metamorphosed as many Silurian fossils. Though in -this state they show their minute structures less perfectly than in -the serpentine specimens, the fact is most important with reference -to the vindication of the animal nature of Eozoon. Another fact whose -significance is not to be over-estimated, is the recognition both by -Dr. Carpenter and myself of specimens in which the canals are occupied -by calcite like that of the organism itself. Quite recently I have, as -mentioned in the last chapter, been enabled to re-examine the locality -at Petite Nation originally discovered by Mr. Lowe, and am prepared to -show that all the facts with reference to the mode of occurrence of -the forms in the beds, and their association with layers of fragmental -Eozoon, are strictly in accordance with the theory that these old -Laurentian limestones are truly marine deposits, holding the remains of -the sea animals of their time. - -[Footnote M: _Ueber das Vorkommen von Eozoon_, 1866.] - -[Footnote N: By Mr. Bicknell at Newbury, and Mr. Burbank at Chelmsford. -The latter gentleman has since maintained that the limestones at the -latter place are not true beds; but his own descriptions and figures, -lead to the belief that this is an error of observation on his part. -The Eozoon in the Chelmsford specimens and in those of Warren, New -York, is in small and rare fragments in serpentinous limestone.] - -Eozoon is not, however, the only witness to the great fact of -Laurentian life, of which it is the most conspicuous exponent. In many -of the Laurentian limestones, mixed with innumerable fragments of -Eozoon, there are other fragments with traces of organic structure of -a different character. There are also casts in silicious matter which -seem to indicate smaller species of Foraminifera. There are besides to -be summoned in evidence the enormous accumulations of carbon already -referred to as existing in the Laurentian rocks, and the worm-burrows, -of which very perfect traces exist in rocks probably of Upper Eozoic -age. - -Other discoveries also are foreshadowed here. The microscope may -yet detect the true nature and affinities of some of the fragments -associated with Eozoon. Less altered portions of the Laurentian rocks -may be found, where even the vegetable matter may retain its organic -forms, and where fossils may be recognised by their external outlines -as well as by their internal structure. The Upper Laurentian and the -Huronian have yet to yield up their stores of life. Thus the time may -come when the rocks now called Primordial shall not be held to be so -in any strict sense, and when swarming dynasties of Protozoa and other -low forms of life may be known as inhabitants of oceans vastly ancient -as compared with even the old Primordial seas. Who knows whether even -the land of the Laurentian time may not have been clothed with plants, -perhaps as much more strange and weird than those of the Devonian and -Carboniferous, as those of the latter are when compared with modern -forests? - - -NOTES TO CHAPTER III. - - -(A.) Sir William E. Logan on the Discovery and Characters of Eozoon. - -[_Journal of Geological Society_, February, 1865.] - - "In the examination of these ancient rocks, the question has often - naturally occurred to me, whether during these remote periods, life - had yet appeared on the earth. The apparent absence of fossils from - the highly crystalline limestones did not seem to offer a proof in - the negative, any more than their undiscovered presence in newer - crystalline limestones where we have little doubt they have been - obliterated by metamorphic action; while the carbon which, in the - form of graphite, constitutes beds, or is disseminated through the - calcareous or siliceous strata of the Laurentian series, seems to be - an evidence of the existence of vegetation, since no one disputes the - organic character of this mineral in more recent rocks. My colleague, - Dr. T. Sterry Hunt, has argued for the existence of organic matters - at the earth's surface during the Laurentian period from the presence - of great beds of iron ore, and from the occurrence of metallic - sulphurets;[O] and finally, the evidence was strengthened by the - discovery of supposed organic forms. These were first brought to me, - in October, 1858, by Mr. J. McMullen, then attached as an explorer to - the Geological Survey of the province, from one of the limestones of - the Laurentian series occurring at the Grand Calumet, on the river - Ottawa. - -[Footnote O: _Quarterly Journal of the Geological Society_, xv., 493.] - - "Any organic remains which may have been entombed in these limestones - would, if they retained their calcareous character, be almost - certainly obliterated by crystallization; and it would only be by the - replacement of the original carbonate of lime by a different mineral - substance, or by an infiltration of such a substance into all the - pores and spaces in and about the fossil, that its form would be - preserved. The specimens from the Grand Calumet present parallel or - apparently concentric layers resembling those of Stromatopora, except - that they anastomose at various points. What were first considered - the layers are composed of crystallized pyroxene, while the then - supposed interstices consist of carbonate of lime. These specimens, - one of which is figured in _Geology of Canada_, p. 49, called to - memory others which had some years previously been obtained from Dr. - James Wilson, of Perth, and were then regarded merely as minerals. - They came, I believe, from masses in Burgess, but whether in place - is not quite certain; and they exhibit similar forms to those of the - Grand Calumet, composed of layers of a dark green magnesian silicate - (loganite); while what were taken for the interstices are filled with - crystalline dolomite. If the specimens from both these places were to - be regarded as the result of unaided mineral arrangement, it appeared - to me strange that identical forms should be derived from minerals - of such different composition. I was therefore disposed to look - upon them as fossils, and as such they were exhibited by me at the - meeting of the American Association for the Advancement of Science, - at Springfield, in August, 1859. See _Canadian Naturalist_, 1859, - iv., 300. In 1862 they were shown to some of my geological friends - in Great Britain; but no microscopic structure having been observed - belonging to them, few seemed disposed to believe in their organic - character, with the exception of my friend Professor Ramsay. - - "One of the specimens had been sliced and submitted to microscopic - observation, but unfortunately it was one of those composed of - loganite and dolomite. In these, the minute structure is rarely - seen. The true character of the specimens thus remained in suspense - until last winter, when I accidentally observed indications of - similar forms in blocks of Laurentian limestone which had been - brought to our museum by Mr. James Lowe, one of our explorers, to - be sawn up for marble. In this case the forms were composed of - serpentine and calc-spar; and slices of them having been prepared - for the microscope, the minute structure was observed in the first - one submitted to inspection. At the request of Mr. Billings, the - palæontologist of our Survey, the specimens were confided for - examination and description to Dr. J. W. Dawson, of Montreal, our - most practised observer with the microscope; and the conclusions at - which he has arrived are appended to this communication. He finds - that the serpentine, which was supposed to replace the organic form, - really fills the interspaces of the calcareous fossil. This exhibits - in some parts a well-preserved organic structure, which Dr. Dawson - describes as that of a Foraminifer, growing in large sessile patches - after the manner of Polytrema and Carpenteria, but of much larger - dimensions, and presenting minute points which reveal a structure - resembling that of other Foraminiferal forms, as, for example - Calcarina and Nummulina. - - "Dr. Dawson's description is accompanied by some remarks by Dr. - Sterry Hunt on the mineralogical relations of the fossil. He - observes that while the calcareous septa which form the skeleton of - the Foraminifer in general remain unchanged, the sarcode has been - replaced by certain silicates which have not only filled up the - chambers, cells, and septal orifices, but have been injected into - the minute tubuli, which are thus perfectly preserved, as may be - seen by removing the calcareous matter by an acid. The replacing - silicates are white pyroxene, serpentine, loganite, and pyrallolite - or rensselaerite. The pyroxene and serpentine are often found - in contact, filling contiguous chambers in the fossil, and were - evidently formed in consecutive stages of a continuous process. In - the Burgess specimens, while the sarcode is replaced by loganite, the - calcareous skeleton, as has already been stated, has been replaced - by dolomite, and the finer parts of the structure have been almost - wholly obliterated. But in the other specimens, where the skeleton - still preserves its calcareous character, the resemblance between - the mode of preservation of the ancient Laurentian Foraminifera, and - that of the allied forms in Tertiary and recent deposits (which, - as Ehrenberg, Bailey, and Pourtales have shown, are injected with - glauconite), is obvious. - - "The Grenville specimens belong to the highest of the three already - mentioned zones of Laurentian limestone, and it has not yet been - ascertained whether the fossil extends to the two conformable lower - ones, or to the calcareous zones of the overlying unconformable - Upper Laurentian series. It has not yet either been determined - what relation the strata from which the Burgess and Grand Calumet - specimens have been obtained bear to the Grenville limestone or - to one another. The zone of Grenville limestone is in some places - about 1500 feet thick, and it appears to be divided for considerable - distances into two or three parts by very thick bands of gneiss. - One of these occupies a position towards the lower part of the - limestone, and may have a volume of between 100 and 200 feet. It is - at the base of the limestone that the fossil occurs. This part of - the zone is largely composed of great and small irregular masses of - white crystalline pyroxene, some of them twenty yards in length by - four or five wide. They appear to be confusedly placed one above - another, with many ragged interstices, and smoothly-worn, rounded, - large and small pits and sub-cylindrical cavities, some of them - pretty deep. The pyroxene, though it appears compact, presents a - multitude of small spaces consisting of carbonate of lime, and many - of these show minute structures similar to that of the fossil. - These masses of pyroxene may characterize a thickness of about 200 - feet, and the interspaces among them are filled with a mixture of - serpentine and carbonate of lime. In general a sheet of pure dark - green serpentine invests each mass of pyroxene; the thickness of the - serpentine, varying from the sixteenth of an inch to several inches, - rarely exceeding half a foot. This is followed in different spots - by parallel, waving, irregularly alternating plates of carbonate of - lime and serpentine, which become gradually finer as they recede - from the pyroxene, and occasionally occupy a total thickness of - five or six inches. These portions constitute the unbroken fossil, - which may sometimes spread over an area of about a square foot, or - perhaps more. Other parts, immediately on the outside of the sheet of - serpentine, are occupied with about the same thickness of what appear - to be the ruins of the fossil, broken up into a more or less granular - mixture of calc-spar and serpentine, the former still showing minute - structure; and on the outside of the whole a similar mixture appears - to have been swept by currents and eddies into rudely parallel and - curving layers; the mixture becoming gradually more calcareous as it - recedes from the pyroxene. Sometimes beds of limestone of several - feet in thickness, with the green serpentine more or less aggregated - into layers, and studded with isolated lumps of pyroxene, are - irregularly interstratified in the mass of rock; and less frequently - there are met with lenticular patches of sandstone or granular - quartzite, of a foot in thickness and several yards in diameter, - holding in abundance small disseminated leaves of graphite. - - "The general character of the rock connected with the fossil produces - the impression that it is a great Foraminiferal reef, in which the - pyroxenic masses represent a more ancient portion, which having - died, and having become much broken up and worn into cavities and - deep recesses, afforded a seat for a new growth of Foraminifera, - represented by the calcareo-serpentinous part. This in its turn - became broken up, leaving in some places uninjured portions of the - general form. The main difference between this Foraminiferal reef and - more recent coral-reefs seems to be that, while in the latter are - usually associated many shells and other organic remains, in the more - ancient one the only remains yet found are those of the animal which - built the reef." - -(B.) NOTE BY SIR WILLIAM E. LOGAN, ON ADDITIONAL SPECIMENS OF EOZOON. - -[_Journal of Geological Society_, August, 1867.] - - "Since the subject of Laurentian fossils was placed before this - Society in the papers of Dr. Dawson, Dr. Carpenter, Dr. T. Sterry - Hunt, and myself, in 1865, additional specimens of Eozoon have been - obtained during the explorations of the Geological Survey of Canada. - These, as in the case of the specimens first discovered, have been - submitted to the examination of Dr. Dawson; and it will be observed, - from his remarks contained in the paper which is to follow, that one - of them has afforded further, and what appears to him conclusive, - evidence of their organic character. The specimens and remarks have - been submitted to Dr. Carpenter, who coincides with Dr. Dawson; - and the object of what I have to say in connection with these new - specimens is merely to point out the localities in which they have - been procured. - - "The most important of these specimens was met with last summer by - Mr. G. H. Vennor, one of the assistants on the Canadian Geological - Survey, in the township of Tudor and county of Hastings, Ontario, - about forty-five miles inland from the north shore of Lake Ontario, - west of Kingston. It occurred on the surface of a layer, three inches - thick, of dark grey micaceous limestone or calc-schist, near the - middle of a great zone of similar rock, which is interstratified - with beds of yellowish-brown sandstone, gray close grained silicious - limestone, white coarsely granular limestone, and bands of dark - bluish compact limestone and black pyritiferous slates, to the whole - of which Mr. Vennor gives a thickness of 1000 feet. Beneath this zone - are gray and pink dolomites, bluish and grayish mica slates, with - conglomerates, diorites, and beds of magnetite, a red orthoclase - gneiss lying at the base. The whole series, according to Mr. Vennor's - section, which is appended, has a thickness of more than 12,000 - feet; but the possible occurrence of more numerous folds than have - hitherto been detected, may hereafter render necessary a considerable - reduction. - - "These measures appear to be arranged in the form of a trough, - to the eastward of which, and probably beneath them, there are - rocks resembling those of Grenville, from which the former differ - considerably in lithological character; it is therefore supposed - that the Hastings series may be somewhat higher in horizon than - that of Grenville. From the village of Madoc, the zone of gray - micaceous limestone, which has been particularly alluded to, runs - to the eastward on one side of the trough, in a nearly vertical - position into Elzivir, and on the other side to the northward, - through the township of Madoc into that of Tudor, partially and - unconformably overlaid in several places by horizontal beds of Lower - Silurian limestone, but gradually spreading, from a diminution of - the dip, from a breadth of half a mile to one of four miles. Where - it thus spreads out in Tudor it becomes suddenly interrupted for a - considerable part of its breadth by an isolated mass of anorthosite - rock, rising about 150 feet above the general plain, and supposed to - belong to the unconformable Upper Laurentian." - - [Subsequent observations, however, render it probable that some of - the above beds may be Huronian.] - - "The Tudor limestone is comparatively unaltered: and, in the specimen - obtained from it, the general form or skeleton of the fossil - (consisting of white carbonate of lime) is imbedded in the limestone, - without the presence of serpentine or other silicate, the colour of - the skeleton contrasting strongly with that of the rock. It does not - sink deep into the rock, the form having probably been loose and much - abraded on what is now the under part, before being entombed. On what - was the surface of the bed, the form presents a well-defined outline - on one side; in this and in the arrangement of the septal layers - it has a marked resemblance to the specimen first brought from the - Calumet, eighty miles to the north-east, and figured in the _Geology - of Canada_, p. 49; while all the forms from the Calumet, like that - from Tudor, are isolated, imbedded specimens, unconnected apparently - with any continuous reef, such as exists at Grenville and the Petite - Nation. It will be seen, from Dr. Dawson's paper, that the minute - structure is present in the Tudor specimen, though somewhat obscure; - but in respect to this, strong subsidiary evidence is derived from - fragments of Eozoon detected by Dr. Dawson in a specimen collected - by myself from the same zone of limestone near the village of Madoc, - in which the canal-system, much more distinctly displayed, is filled - with carbonate of lime, as quoted from Dr. Dawson by Dr. Carpenter - in the Journal of this Society for August, 1866. - - "In Dr. Dawson's paper mention is made of specimens from Wentworth, - and others from Long Lake. In both of these localities the rock - yielding them belongs to the Grenville band, which is the uppermost - of the three great bands of limestone hitherto described as - interstratified in the Lower Laurentian series. That at Long Lake, - situated about twenty-five miles north of Côte St. Pierre in the - Petite Nation seigniory, where the best of the previous specimens - were obtained, is in the direct run of the limestone there: and like - it the Long Lake rock is of a serpentinous character. The locality - in Wentworth occurs on Lake Louisa, about sixteen miles north of - east from that of the first Grenville specimens, from which Côte St. - Pierre is about the same distance north of west, the lines measuring - these distances running across several important undulations in - the Grenville band in both directions. The Wentworth specimens are - imbedded in a portion of the Grenville band, which appears to have - escaped any great alteration, and is free from serpentine, though a - mixture of serpentine with white crystalline limestone occurs in the - band within a mile of the spot. From this grey limestone, which has - somewhat the aspect of a conglomerate, specimens have been obtained - resembling some of the figures given by Gümbel in his _Illustrations_ - of the forms met with by him in the Laurentian rocks of Bavaria. - - "In decalcifying by means of a dilute acid some of the specimens - from Côte St. Pierre, placed in his hands in 1864-65, Dr. Carpenter - found that the action of the acid was arrested at certain portions - of the skeleton, presenting a yellowish-brown surface; and he showed - me, two or three weeks ago, that in a specimen recently given him, - from the same locality, considerable portions of the general form - remained undissolved by such an acid. On partially reducing some - of these portions to a powder; however, we immediately observed - effervescence by the dilute acid; and strong acid produced it without - bruising. There is little doubt that these portions of the skeleton - are partially replaced by dolomite, as more recent fossils are - often known to be, of which there is a noted instance in the Trenton - limestone of Ottawa. But the circumstance is alluded to for the - purpose of comparing these dolomitized portions of the skeleton with - the specimens from Burgess, in which the replacement of the septal - layers by dolomite appears to be the general condition. In such of - these specimens as have been examined the minute structure seems to - be wholly, or almost wholly, destroyed; but it is probable that upon - a further investigation of the locality some spots will be found - to yield specimens in which the calcareous skeleton still exists - unreplaced by dolomite; and I may safely venture to predict that in - such specimens the minute structure, in respect both to canals and - tubuli, will be found as well preserved as in any of the specimens - from Côte St. Pierre. - - "It was the general form on weathered surfaces, and its strong - resemblance to Stromatopora, which first attracted my attention to - Eozoon; and the persistence of it in two distinct minerals, pyroxene - and loganite, emboldened me, in 1857, to place before the Meeting of - the American Association for the Advancement of Science specimens of - it as probably a Laurentian fossil. After that, the form was found - preserved in a third mineral, serpentine; and in one of the previous - specimens it was then observed to pass continuously through two - of the minerals, pyroxene and serpentine. Now we have it imbedded - in limestone, just as most fossils are. In every case, with the - exception of the Burgess specimens, the general form is composed of - carbonate of lime; and we have good grounds for supposing it was - originally so in the Burgess specimens also. If, therefore, with such - evidence, and without the minute structure, I was, upon a calculation - of chances, disposed, in 1857, to look upon the form as organic, much - more must I so regard it when the chances have been so much augmented - by the subsequent accumulation of evidence of the same kind, and - the addition of the minute structure, as described by Dr. Dawson, - whose observations have been confirmed and added to by the highest - British authority upon the class of animals to which the form has - been referred, leaving in my mind no room whatever for doubt of its - organic character. Objections to it as an organism have been made by - Professors King and Rowney: but these appear to me to be based upon - the supposition that because some parts simulating organic structure - are undoubtedly mere mineral arrangement, therefore all parts are - mineral. Dr. Dawson has not proceeded upon the opposite supposition, - that because some parts are, in his opinion, undoubtedly organic, - therefore all parts simulating organic structure are organic; but - he has carefully distinguished between the mineral and organic - arrangements. I am aware, from having supplied him with a vast number - of specimens prepared for the microscope by the lapidary of the - Canadian Survey, from a series of rocks of Silurian and Huronian, - as well as Laurentian age, and from having followed the course of - his investigation as it proceeded, that nearly all the points of - objection of Messrs. King and Rowney passed in review before him - prior to his coming to the conclusions which he has published." - -_Ascending Section of the Eozoic Rocks in the County of Hastings, -Ontario._ By Mr. H. G. Vennor. - - Feet. - 1. Reddish and flesh-coloured granitic gneiss, the thickness - of which is unknown; estimated at not less than 2,000 - - 2. Grayish and flesh-coloured gneiss, sometimes hornblendic, - passing towards the summit into a dark mica-schist, - and including portions of greenish-white diorite; - mean of several pretty closely agreeing measurements, 10,400 - - 3. Crystalline limestone, sometimes magnesian, including - lenticular patches of quartz, and broken and - contorted layers of quartzo-felspathic rock, rarely above - a few inches in thickness. This limestone, which includes - in Elzivir a one-foot bed of graphite, is sometimes - very thin, but in other places attains a thickness - of 750 feet; estimated as averaging 400 - - 4. Hornblendic and dioritic rocks, massive or schistose, - occasionally associated near the base with dark - micaceous schists, and also with chloritic and epidotic - rocks, including beds of magnetite; average thickness 4,200 - - 5. Crystalline and somewhat granular magnesian - limestone, occasionally interstratified with diorites, and - near the base with silicious slates and small beds of - impure steatite 330 - - This limestone, which is often silicious and ferruginous, - is metalliferous, holding disseminated copper - pyrites, blende, mispickel, and iron pyrites, the latter - also sometimes in beds of two or three feet. Gold occurs - in the limestone at the village of Madoc, associated with - an argentiferous gray copper ore, and in irregular veins - with bitter-spar, quartz, and a carbonaceous matter, at - the Richardson mine in Madoc. - - 6. Gray silicious or fined-grained mica-slates, with - an interstratified mass of about sixty feet of yellowish-white - dolomite divided into beds by thin layers of the - mica-slate, which, as well as the dolomite, often becomes - conglomerate, including rounded masses of gneiss and - quartzite from one to twelve inches in diameter 400 - - 7. Bluish and grayish micaceous slate, interstratified - with layers of gneiss, and occasionally holding crystals - of magnetite. The whole division weathers to a rusty-brown 500 - - 8. Gneissoid micaceous quartzites, banded gray and - white, with a few interstratified beds of silicious - limestone, and, like the last division, weathering rusty - brown 1,900 - - 9. Gray micaceous limestone, sometimes plumbaginous, - becoming on its upper portion a calc-schist, but - more massive towards the base, where it is interstratified - with occasional layers of diorite, and layers of a - rusty-weathering gneiss like 8 1,100 - - This division in Tudor is traversed by numerous - N.W. and S.E. veins, holding galena in a gangue of - calcite and barytine. The Eozoon from Tudor here - described was obtained from about the middle of this - calcareous division, which appears to form the summit - of the Hastings series. - ------ - Total thickness 21,130 - -[Illustration: - PLATE IV. - - _Magnified and Restored Section of a portion of Eozoon Canadense._ - -The portions in brown show the animal matter of the Chambers, Tubuli, -Canals, and Pseudopodia; the portions uncoloured, the calcareous skeleton.] - -[Illustration: Fig. 12. _Amœba._ Fig. 13. _Actinophrys._ - -From original sketches.] - - - - -CHAPTER IV. - -WHAT IS EOZOON? - - -The shortest answer to this question is, that this ancient fossil -is the skeleton of a creature belonging to that simple and humbly -organized group of animals which are known by the name Protozoa. If -we take as a familiar example of these the gelatinous and microscopic -creature found in stagnant ponds, and known as the _Amœba_[P] (fig. -12), it will form a convenient starting point. Viewed under a low -power, it appears as a little patch of jelly, irregular in form, and -constantly changing its aspect as it moves, by the extension of parts -of its body into finger-like processes or pseudopods which serve as -extempore limbs. When moving on the surface of a slip of glass under -the microscope, it seems, as it were, to flow along rather than creep, -and its body appears to be of a semi-fluid consistency. It may be taken -as an example of the least complex forms of animal life known to us, -and is often spoken of by naturalists as if it were merely a little -particle of living and scarcely organized jelly or protoplasm. When -minutely examined, however, it will not be found so simple as it at -first sight appears. Its outer layer is clear or transparent, and more -dense than the inner mass, which seems granular. It has at one end a -curious vesicle which can be seen gradually to expand and become filled -with a clear drop of liquid, and then suddenly to contract and expel -the contained fluid through a series of pores in the adjacent part of -the outer wall. This is the so-called pulsating vesicle, and is an -organ both of circulation and excretion. In another part of the body -may be seen the nucleus, which is a little cell capable, at certain -times, of producing by its division new individuals. Food when taken -in through the wall of the body forms little pellets, which become -surrounded by a digestive liquid exuded from the enclosing mass into -rounded cavities or extemporised stomachs. Minute granules are seen -to circulate in the gelatinous interior, and may be substitutes for -blood-cells, and the outer layer of the body is capable of protrusion -in any direction into long processes, which are very mobile, and used -for locomotion and prehension. Further, this creature, though destitute -of most of the parts which we are accustomed to regard as proper to -animals, seems to exercise volition, and to show the same appetites -and passions with animals of higher type. I have watched one of these -animalcules endeavouring to swallow a one-celled plant as long as its -own body; evidently hungry and eager to devour the tempting morsel, it -stretched itself to its full extent, trying to envelope the object of -its desire. It failed again and again; but renewed the attempt, until -at length, convinced of its hopelessness, it flung itself away as if in -disappointment, and made off in search of something more manageable. -With the Amœba are found other types of equally simple Protozoa, but -somewhat differently organized. One of these, _Actinophrys_ (fig. 13), -has the body globular and unchanging in form, the outer wall of greater -thickness; the pulsating vesicle like a blister on the surface, and the -pseudopods long and thread-like. Its habits are similar to those of the -Amœba, and I introduce it to show the variations of form and structure -possible even among these simple creatures. - -[Footnote P: The alternating animal, alluding to its change of form.] - -[Illustration: Fig. 14. _Entosolenia._ - -A one-celled Foraminifer. Magnified as a transparent object.] - -[Illustration: Fig. 15. _Biloculina._ - -A many-chambered Foraminifer. Magnified as a transparent object.] - -[Illustration: Fig. 16. _Polystomella._ - -A spiral Foraminifer. Magnified as an opaque object.] - -The Amœba and Actinophrys are fresh water animals, and are destitute -of any shell or covering. But in the sea there exist swarms of similar -creatures, equally simple in organization, but gifted with the power of -secreting around their soft bodies beautiful little shells or crusts of -carbonate of lime, having one orifice, and often in addition multitudes -of microscopic pores through which the soft gelatinous matter can ooze, -and form outside finger-like or thread-like extensions for collecting -food. In some cases the shell consists of a single cavity only, but in -most, after one cell is completed, others are added, forming a series -of cells or chambers communicating with each other, and often arranged -spirally or otherwise in most beautiful and symmetrical forms. Some of -these creatures, usually named Foraminifera, are locomotive, others -sessile and attached. Most of them are microscopic, but some grow by -multiplication of chambers till they are a quarter of an inch or more -in breadth. (Figs. 14 to 17.) - -[Illustration: Fig. 17. _Polymorphina._ - -A many-chambered Foraminifer. Magnified as an opaque object. Figs. 14 -to 17 are from original sketches of Post-pliocene specimens.] - -The original skeleton or primary cell-wall of most of these creatures -is seen under the microscope to be perforated with innumerable pores, -and is extremely thin. When, however, owing to the increased size of -the shell, or other wants of the creature, it is necessary to give -strength, this is done by adding new portions of carbonate of lime to -the outside, and to these Dr. Carpenter has given the appropriate name -of "supplemental skeleton;" and this, when covered by new growths, -becomes what he has termed an "intermediate skeleton." The supplemental -skeleton is also traversed by tubes, but these are often of larger size -than the pores of the cell-wall, and of greater length, and branched in -a complicated manner. (Fig. 20.) Thus there are microscopic characters -by which these curious shells can be distinguished from those of -other marine animals; and by applying these characters we learn that -multitudes of creatures of this type have existed in former periods of -the world's history, and that their shells, accumulated in the bottom -of the sea, constitute large portions of many limestones. The manner in -which such accumulation takes place we learn from what is now going on -in the ocean, more especially from the result of the recent deep-sea -dredging expeditions. The Foraminifera are vastly numerous, both near -the surface and at the bottom of the sea, and multiply rapidly; and -as successive generations die, their shells accumulate on the ocean -bed, or are swept by currents into banks, and thus in process of time -constitute thick beds of white chalky material, which may eventually -be hardened into limestone. This process is now depositing a great -thickness of white ooze in the bottom of the ocean; and in times past -it has produced such vast thicknesses of calcareous matter as the chalk -and the nummulitic limestone of Europe and the orbitoidal limestone -of America. The chalk, which alone attains a maximum thickness of 1000 -feet, and, according to Lyell, can be traced across Europe for 1100 -geographical miles, may be said to be entirely composed of shells -of Foraminifera imbedded in a paste of still more minute calcareous -bodies, the Coccoliths, which are probably products of marine -vegetable life, if not of some animal organism still simpler than the -Foraminifera. - -Lastly, we find that in the earlier geological ages there existed -much larger Foraminifera than any found in our present seas; and that -these, always sessile on the bottom, grew by the addition of successive -chambers, in the same manner with the smaller species. To some of these -we shall return in the sequel. In the meantime we shall see what claims -Eozoon has to be included among them. - -Let us, then, examine the structure of Eozoon, taking a typical -specimen, as we find it in the limestone of Grenville or Petite Nation. -In such specimens the skeleton of the animal is represented by a white -crystalline marble, the cavities of the cells by green serpentine, the -mode of whose introduction we shall have to consider in the sequel. -The lowest layer of serpentine represents the first gelatinous coat -of animal matter which grew upon the bottom, and which, if we could -have seen it before any shell was formed upon its surface, must have -resembled, in appearance at least, the shapeless coat of living slime -found in some portions of the bed of the deep sea, which has received -from Huxley the name _Bathybius_, and which is believed to be a -protozoon of indefinite extension, though it may possibly be merely the -pulpy sarcode of sponges and similar things penetrating the ooze at -their bases. On this primary layer grew a delicate calcareous shell, -perforated by innumerable minute tubuli, and by some larger pores or -septal orifices, while supported at intervals by perpendicular plates -or pillars. Upon this again was built up, in order to strengthen it, -a thickening or supplemental skeleton, more dense, and destitute of -fine tubuli, but traversed by branching canals, through which the -soft gelatinous matter could pass for the nourishment of the skeleton -itself, and the extension of pseudopods beyond it. (Fig. 10.) So was -formed the first layer of Eozoon, which seems in some cases to have -spread by lateral extension over several inches of sea bottom. On this -the process of growth of successive layers of animal sarcode and of -calcareous skeleton was repeated again and again, till in some cases -even a hundred or more layers were formed. (Photograph, Plate III., -and nature print, Plate V.) As the process went on, however, the -vitality of the organism became exhausted, probably by the deficient -nourishment of the central and lower layers making greater and greater -demands on those above, and so the succeeding layers became thinner, -and less supplemental skeleton was developed. Finally, toward the -top, the regular arrangement in layers was abandoned, and the cells -became a mass of rounded chambers, irregularly piled up in what Dr. -Carpenter has termed an "acervuline" manner, and with very thin walls -unprotected by supplemental skeleton. Then the growth was arrested, -and possibly these upper layers gave off reproductive germs, fitted -to float or swim away and to establish new colonies. We may have -such reproductive germs in certain curious globular bodies, like -loose cells, found in connection with irregular Eozoon in one of -the Laurentian limestones at Long Lake and elsewhere. These curious -organisms I observed some years ago, but no description of them was -published at the time, as I hoped to obtain better examples. I now -figure some of them, and give their description in a note. (Fig. 18). -I have recently obtained numerous additional examples from the beds -holding Eozoon at St. Pierre, on the Ottawa. They occur at this place -on the surface of layers of the limestone in vast numbers, as if they -had been growing separately on the bottom, or had been drifted over -it by currents. These we shall further discuss hereafter. Such was -the general mode of growth of Eozoon, and we may now consider more in -detail some questions as to its gigantic size, its precise mode of -nutrition, the arrangement of its parts, its relations to more modern -forms, and the effects of its growth in the Laurentian seas. In the -meantime a study of our illustration, Plate IV., which is intended as a -magnified restoration of the animal, will enable the reader distinctly -to understand its structure and probable mode of growth, and to avail -himself intelligently of the partial representations of its fossilized -remains in the other plates and woodcuts. - -[Illustration: Fig. 18. _Minute Foraminiferal forms from the Laurentian -of Long Lake._ - -Highly magnified. (_a._) Single cell, showing tubulated wall. (_b, c._) -Portions of same more highly magnified. (_d._) Serpentine cast of a -similar chamber, decalcified, and showing casts of tubuli.] - -With respect to its size, we shall find in a subsequent chapter that -this was rivalled by some succeeding animals of the same humble type -in the Silurian age; and that, as a whole, foraminiferal animals have -been diminishing in size in the lapse of geological time. It is indeed -a fact of so frequent occurrence that it may almost be regarded as -a law of the introduction of new forms of life, that they assume in -their early history gigantic dimensions, and are afterwards continued -by less magnificent species. The relations of this to external -conditions, in the case of higher animals, are often complex and -difficult to understand; but in organisms so low as Eozoon and its -allies, they lie more on the surface. Such creatures may be regarded -as the simplest and most ready media for the conversion of vegetable -matter into animal tissues, and their functions are almost entirely -limited to those of nutrition. Hence it is likely that they will be -able to appear in the most gigantic forms under such conditions as -afford them the greatest amount of pabulum for the nourishment of -their soft parts and for their skeletons. There is reason to believe, -for example, that the occurrence, both in the chalk and the deep-sea -mud, of immense quantities of the minute bodies known as Coccoliths -along with Foraminifera, is not accidental. The Coccoliths appear to -be grains of calcareous matter formed in minute plants adapted to a -deep-sea habitat; and these, along with the vegetable and animal debris -constantly being derived from the death of the living things at the -surface, afford the material both of sarcode and shell. Now if the -Laurentian graphite represents an exuberance of vegetable growth in -those old seas proportionate to the great supplies of carbonic acid -in the atmosphere and in the waters, and if the Eozoic ocean was even -better supplied with carbonate of lime than those Silurian seas whose -vast limestones bear testimony to their richness in such material, we -can easily imagine that the conditions may have been more favourable -to a creature like Eozoon than those of any other period of geological -time. - -Growing, as Eozoon did, on the floor of the ocean, and covering wide -patches with more or less irregular masses, it must have thrown up from -its whole surface its pseudopods to seize whatever floating particles -of food the waters carried over it. There is also reason to believe, -from the outline of certain specimens, that it often grew upward in -cylindrical or club-shaped forms, and that the broader patches were -penetrated by large pits or oscula, admitting the sea-water deeply into -the substance of the masses. In this way its growth might be rapid and -continuous; but it does not seem to have possessed the power of growing -indefinitely by new and living layers covering those that had died, -in the manner of some corals. Its life seems to have had a definite -termination, and when that was reached an entirely new colony had to -be commenced. In this it had more affinity with the Foraminifera, as -we now know them, than with the corals, though practically it had the -same power with the coral polyps of accumulating limestone in the sea -bottom, a power indeed still possessed by its foraminiferal successors. -In the case of coral limestones, we know that a large proportion of -these consist not of continuous reefs but of fragments of coral mixed -with other calcareous organisms, spread usually by waves and currents -in continuous beds over the sea bottom. In like manner we find in -the limestones containing Eozoon, layers of fragmental matter which -shows in places the characteristic structures, and which evidently -represents the debris swept from the Eozoic masses and reefs by the -action of the waves. It is with this fragmental matter that the small -rounded organisms already referred to most frequently occur; and while -they may be distinct animals, they may also be the fry of Eozoon, or -small portions of its acervuline upper surface floated off in a living -state, and possibly capable of living independently and of founding new -colonies. - -It is only by a somewhat wild poetical licence that Eozoon has been -represented as a "kind of enormous composite animal stretching from the -shores of Labrador to Lake Superior, and thence northward and southward -to an unknown distance, and forming masses 1500 feet in depth." We may -discuss by-and-by the question of the composite nature of masses of -Eozoon, and we see in the corals evidence of the great size to which -composite animals of a higher grade can attain. In the case of Eozoon -we must imagine an ocean floor more uniform and level than that now -existing. On this the organism would establish itself in spots and -patches. These might finally become confluent over large areas, just -as massive corals do. As individual masses attained maturity and died, -their pores would be filled up with limestone or silicious deposits, -and thus could form a solid basis for new generations, and in this way -limestone to an indefinite extent might be produced. Further, wherever -such masses were high enough to be attacked by the breakers, or where -portions of the sea bottom were elevated, the more fragile parts of the -surface would be broken up and scattered widely in beds of fragments -over the bottom of the sea, while here and there beds of mud or sand -or of volcanic debris would be deposited over the living or dead -organic mass, and would form the layers of gneiss and other schistose -rocks interstratified with the Laurentian limestone. In this way, in -short, Eozoon would perform a function combining that which corals and -Foraminifera perform in the modern seas; forming both reef limestones -and extensive chalky beds, and probably living both in the shallow and -the deeper parts of the ocean. If in connection with this we consider -the rapidity with which the soft, simple, and almost structureless -sarcode of these Protozoa can be built up, and the probability that -they were more abundantly supplied with food, both for nourishing their -soft parts and skeletons, than any similar creatures in later times, we -can readily understand the great volume and extent of the Laurentian -limestones which they aided in producing. I say aided in producing, -because I would not desire to commit myself to the doctrine that the -Laurentian limestones are wholly of this origin. There may have been -other animal limestone-builders than Eozoon, and there may have been -limestones formed by plants like the modern Nullipores or by merely -mineral deposition. - -[Illustration: Fig. 19. _Section of a Nummulite, from Eocene Limestone -of Syria._ - -Showing chambers, tubuli, and canals. Compare this and fig. 20 with -figs. 10 and 11.] - -[Illustration: Fig. 20. _Portion of shell of Calcarina._ - -Magnified, after Carpenter. (_a._) Cells. (_b._) Original cell-wall -with tubuli. (_c._) Supplementary skeleton with canals.] - -Its relations to modern animals of its type have been very clearly -defined by Dr. Carpenter. In the structure of its proper wall and its -fine parallel perforations, it resembles the _Nummulites_ and their -allies; and the organism may therefore be regarded as an aberrant -member of the Nummuline group, which affords some of the largest and -most widely distributed of the fossil Foraminifera. This resemblance -may be seen in fig. 19. To the Nummulites it also conforms in its -tendency to form a supplemental or intermediate skeleton with canals, -though the canals themselves in their arrangement more nearly resemble -Calcarina, which is represented in fig. 20. In its superposition of -many layers, and in its tendency to a heaped up or acervuline irregular -growth it resembles _Polytrema_ and _Tinoporus_, forms of a different -group in so far as shell-structure is concerned. It may thus be -regarded as a composite type, combining peculiarities now observed in -two groups, or it may be regarded as a representative in the Nummuline -series of Polytrema and Tinoporus in the Rotaline series. At the time -when Dr. Carpenter stated these affinities, it might be objected that -Foraminifera of these families are in the main found in the Modern and -Tertiary periods. Dr. Carpenter has since shown that the curious oval -Foraminifer called _Fusulina_, found in the coal formation, is in like -manner allied to both Nummulites and Rotalines; and still more recently -Mr. Brady has discovered a true Nummulite in the Lower Carboniferous of -Belgium. This group being now fairly brought down to the Palæozoic, we -may hope finally to trace it back to the Primordial, and thus to bring -it still nearer to Eozoon in time. - -[Illustration: Fig. 21. _Foraminiferal Rock Builders._ - -(_a._) Nummulites lævigata--Eocene. (_b._) The same, showing chambered -interior. (_c._) Milioline limestone, magnified--Eocene, Paris. (_d._) -Hard Chalk, section magnified--Cretaceous.] - -Though Eozoon was probably not the only animal of the Laurentian seas, -yet it was in all likelihood the most conspicuous and important as -a collector of calcareous matter, filling the same place afterwards -occupied by the reef-building corals. Though probably less efficient -than these as a constructor of solid limestones, from its less -permanent and continuous growth, it formed wide floors and patches -on the sea-bottom, and when these were broken up vast quantities of -limestone were formed from their debris. It must also be borne in mind -that Eozoon was not everywhere infiltrated with serpentine or other -silicious minerals; quantities of its substance were merely filled -with carbonate of lime, resembling the chamber-wall so closely that -it is nearly impossible to make out the difference, and thus is likely -to pass altogether unobserved by collectors, and to baffle even the -microscopist. (Fig. 24.) Although therefore the layers which contain -well characterized Eozoon are few and far between, there is reason to -believe that in the composition of the limestones of the Laurentian -it bore no small part, and as these limestones are some of them -several hundreds of feet in thickness, and extend over vast areas, -Eozoon may be supposed to have been as efficient a world-builder as -the Stromatoporæ of the Silurian and Devonian, the Globigerinæ and -their allies in the chalk, or the Nummulites and Miliolites in the -Eocene. The two latter groups of rock-makers are represented in our -cut, fig. 21; the first will engage our attention in chapter sixth. It -is a remarkable illustration of the constancy of natural causes and of -the persistence of animal types, that these humble Protozoans, which -began to secrete calcareous matter in the Laurentian period, have been -continuing their work in the ocean through all the geological ages, -and are still busy in accumulating those chalky muds with which recent -dredging operations in the deep sea have made us so familiar. - - -NOTES TO CHAPTER IV. - - -(A.) Original Description of Eozoon Canadense. - -[As given by the author in the _Journal of the Geological Society_, -February, 1865.] - - "At the request of Sir W. E. Logan, I have submitted to microscopic - examination slices of certain peculiar laminated forms, consisting - of alternate layers of carbonate of lime and serpentine, and of - carbonate of lime and white pyroxene, found in the Laurentian - limestone of Canada, and regarded by Sir William as possibly fossils. - I have also examined slices of a large number of limestones from the - Laurentian series, not showing the forms of these supposed fossils. - - "The specimens first mentioned are masses, often several inches in - diameter, presenting to the naked eye alternate laminæ of serpentine, - or of pyroxene, and carbonate of lime. Their general aspect, as - remarked by Sir W. E. Logan (_Geology of Canada_, 1863, p. 49), - reminds the observer of that of the Silurian corals of the genus - Stromatopora, except that the laminæ diverge from and approach each - other, and frequently anastomose or are connected by transverse septa. - - "Under the microscope the resemblance to Stromatopora is seen to - be in general form merely, and no trace appears of the radiating - pillars characteristic of that genus. The laminæ of serpentine and - pyroxene present no organic structure, and the latter mineral is - highly crystalline. The laminæ of carbonate of lime, on the contrary, - retain distinct traces of structures which cannot be of a crystalline - or concretionary character. They constitute parallel or concentric - partitions of variable thickness, enclosing flattened spaces or - chambers, frequently crossed by transverse plates or septa, in some - places so numerous as to give a vesicular appearance, in others - occurring only at rare intervals. The laminæ themselves are excavated - on their sides into rounded pits, and are in some places traversed by - canals, or contain secondary rounded cells, apparently isolated. In - addition to these general appearances, the substance of the laminæ, - where most perfectly preserved, is seen to present a fine granular - structure, and to be penetrated by numerous minute tubuli, which - are arranged in bundles of great beauty and complexity, diverging - in sheaf-like forms, and in their finer extensions anastomosing so - as to form a network (figs. 10 and 28). In transverse sections, and - under high powers, the tubuli are seen to be circular in outline, and - sharply defined (fig. 29). In longitudinal sections, they sometimes - present a beaded or jointed appearance. Even where the tubular - structure is least perfectly preserved, traces of it can still be - seen in most of the slices, though there are places in which the - laminæ are perfectly compact, and perhaps were so originally. - - "With respect to the nature and probable origin of the appearances - above described, I would make the following remarks:-- - - "1. The serpentine and pyroxene which fill the cavities of the - calcareous matter have no appearance of concretionary structure. - On the contrary, their aspect is that of matter introduced by - infiltration, or as sediment, and filling spaces previously existing. - In other words, the calcareous matter has not been moulded on the - forms of the serpentine and augite, but these have filled spaces - or chambers in a hard calcareous mass. This conclusion is further - confirmed by the fact, to be referred to in the sequel, that the - serpentine includes multitudes of minute foreign bodies, while the - calcareous matter is uniform and homogeneous. It is also to be - observed that small veins of carbonate of lime occasionally traverse - the specimen's, and in their entire absence of structures other than - crystalline, present a striking contrast to the supposed fossils. - - "2. Though the calcareous laminæ have in places a crystalline - cleavage, their forms and structures have no relation to this. Their - cells and canals are rounded, and have smooth walls, which are - occasionally lined with films apparently of carbonaceous matter. - Above all, the minute tubuli are different from anything likely to - occur in merely crystalline calc-spar. While in such rocks little - importance might be attached to external forms simulating the - appearances of corals, sponges, or other organisms, these delicate - internal structures have a much higher claim to attention. Nor is - there any improbability in the preservation of such minute parts in - rocks so highly crystalline, since it is a circumstance of frequent - occurrence in the microscopic examination of fossils that the finest - structures are visible in specimens in which the general form and the - arrangement of parts have been obliterated. It is also to be observed - that the structure of the calcareous laminæ is the same, whether the - intervening spaces are filled with serpentine or with pyroxene. - - "3. The structures above described are not merely definite and - uniform, but they are of a kind proper to animal organisms, and - more especially to one particular type of animal life, as likely as - any other to occur under such circumstances: I refer to that of the - Rhizopods of the order Foraminifera. The most important point of - difference is in the great size and compact habit of growth of the - specimens in question; but there seems no good reason to maintain - that Foraminifera must necessarily be of small size, more especially - since forms of considerable magnitude referred to this type are known - in the Lower Silurian. Professor Hall has described specimens of - Receptaculites twelve inches in diameter; and the fossils from the - Potsdam formation of Labrador, referred by Mr. Billings to the genus - Archæocyathus, are examples of Protozoa with calcareous skeletons - scarcely inferior in their massive style of growth to the forms now - under consideration. - - "These reasons are, I think, sufficient to justify me in regarding - these remarkable structures as truly organic, and in searching for - their nearest allies among the Foraminifera. - - "Supposing then that the spaces between the calcareous laminæ, as - well as the canals and tubuli traversing their substance, were once - filled with the sarcode body of a Rhizopod, comparisons with modern - forms at once suggest themselves. - - "From the polished specimens in the Museum of the Canadian Geological - Survey, it appears certain that these bodies were sessile by a broad - base, and grew by the addition of successive layers of chambers - separated by calcareous laminæ, but communicating with each other by - canals or septal orifices sparsely and irregularly distributed. Small - specimens have thus much the aspect of the modern genera Carpenteria - and Polytrema. Like the first of these genera, there would also seem - to have been a tendency to leave in the midst of the structure a - large central canal, or deep funnel-shaped or cylindrical opening, - for communication with the sea-water. Where the laminæ coalesce, and - the structure becomes more vesicular, it assumes the 'acervuline' - character seen in such modern forms as Nubecularia. - - "Still the magnitude of these fossils is enormous when compared with - the species of the genera above named; and from the specimens in the - larger slabs from Grenville, in the museum of the Canadian Survey, - it would seem that these organisms grew in groups, which ultimately - coalesced, and formed large masses penetrated by deep irregular - canals; and that they continued to grow at the surface, while the - lower parts became dead and were filled up with infiltrated matter or - sediment. In short, we have to imagine an organism having the habit - of growth of Carpenteria, but attaining to an enormous size, and by - the aggregation of individuals assuming the aspect of a coral reef. - - "The complicated systems of tubuli in the Laurentian fossil indicate, - however, a more complex structure than that of any of the forms - mentioned above. I have carefully compared these with the similar - structures in the 'supplementary skeleton' (or the shell-substance - that carries the vascular system) of Calcarina and other forms, and - can detect no difference except in the somewhat coarser texture of - the tubuli in the Laurentian specimens. It accords well with the - great dimensions of these, that they should thus thicken their walls - with an extensive deposit of tubulated calcareous matter; and from - the frequency of the bundles of tubuli, as well as from the thickness - of the partitions, I have no doubt that all the successive walls, as - they were formed, were thickened in this manner, just as in so many - of the higher genera of more modern Foraminifera. - - "It is proper to add that no spicules, or other structures indicating - affinity to the Sponges, have been detected in any of the specimens. - - "As it is convenient to have a name to designate these forms, I - would propose that of Eozoon, which will be specially appropriate to - what seems to be the characteristic fossil of a group of rocks which - must now be named Eozoic rather than Azoic. For the species above - described, the specific name of Canadense has been proposed. It may - be distinguished by the following characters:-- - - "Eozoon Canadense; _gen. et spec. nov._ - - "_General form._--Massive, in large sessile patches or irregular - cylinders, growing at the surface by the addition of successive - laminæ. - - "_Internal structure._--Chambers large, flattened, irregular, with - numerous rounded extensions, and separated by walls of variable - thickness, which are penetrated by septal orifices irregularly - disposed. Thicker parts of the walls with bundles of fine branching - tubuli. - - "These characters refer specially to the specimens from Grenville and - the Calumet. There are others from Perth, C. W., which show more - regular laminæ, and in which the tubuli have not yet been observed; - and a specimen from Burgess, C. W., contains some fragments of laminæ - which exhibit, on one side, a series of fine parallel tubuli like - those of Nummulina. These specimens may indicate distinct species; - but on the other hand, their peculiarities may depend on different - states of preservation. - - "With respect to this last point, it may be remarked that some of - the specimens from Grenville and the Calumet show the structure of - the laminæ with nearly equal distinctness, whether the chambers are - filled with serpentine or pyroxene, and that even the minute tubuli - are penetrated and filled with these minerals. On the other hand, - there are large specimens in the collection of the Canadian Survey - in which the lower and still parts of the organism are imperfectly - preserved in pyroxene, while the upper parts are more perfectly - mineralized with serpentine." - - * * * * * - - [The following note was added in a reprint of the paper in the - _Canadian Naturalist_, April, 1865.] - - "Since the above was written, thick slices of Eozoon from Grenville - have been prepared, and submitted to the action of hydrochloric acid - until the carbonate of lime was removed. The serpentine then remains - as a cast of the interior of the chambers, showing the form of their - original sarcode-contents. The minute tubuli are found also to have - been filled with a substance insoluble in the acid, so that casts - of these also remain in great perfection, and allow their general - distribution to be much better seen than in the transparent slices - previously prepared. These interesting preparations establish the - following additional structural points:-- - - "1. That the whole mass of sarcode throughout the organism was - continuous; the apparently detached secondary chambers being, as - I had previously suspected, connected with the larger chambers by - canals filled with sarcode. - - "2. That some of the irregular portions without lamination are not - fragmentary, but due to the acervuline growth of the animal; and that - this irregularity has been produced in part by the formation of - projecting patches of supplementary skeleton, penetrated by beautiful - systems of tubuli. These groups of tubuli are in some places very - regular, and have in their axes cylinders of compact calcareous - matter. Some parts of the specimens present arrangements of this kind - as symmetrical as in any modern Foraminiferal shell. - - "3. That all except the very thinnest portions of the walls of - the chambers present traces, more or less distinct, of a tubular - structure. - - "4. These facts place in more strong contrast the structure of - the regularly laminated species from Burgess, which do not show - tubuli, and that of the Grenville specimens, less regularly - laminated and tubulous throughout. I hesitated however to regard - these two as distinct species, in consequence of the intermediate - characters presented by specimens from the Calumet, which are - regularly laminated like those of Burgess, and tubulous like those - of Grenville. It is possible that in the Burgess specimens, tubuli, - originally present, have been obliterated, and in organisms of this - grade, more or less altered by the processes of fossilisation, large - series of specimens should be compared before attempting to establish - specific distinctions." - - -(B.) Original Description of the Specimens added by Dr. Carpenter to -the above--in a Letter to Sir W. E. Logan. - -[_Journal of Geological Society_, February, 1865.] - - "The careful examination which I have made, in accordance with - the request you were good enough to convey to me from Dr. Dawson - and to second on your own part, with the structure of the very - extraordinary fossil which you have brought from the Laurentian - rocks of Canada,[Q] enables me most unhesitatingly to confirm the - sagacious determination of Dr. Dawson as to its Rhizopod characters - and Foraminiferal affinities, and at the same time furnishes new - evidence of no small value in support of that determination. In - this examination I have had the advantage of a series of sections - of the fossil much superior to those submitted to Dr. Dawson; and - also of a large series of decalcified specimens, of which Dr. Dawson - had only the opportunity of seeing a few examples after his memoir - had been written. These last are peculiarly instructive; since - in consequence of the complete infiltration of the chambers and - canals, originally occupied by the sarcode-body of the animal, by - mineral matter insoluble in dilute nitric acid, the removal of the - calcareous shell brings into view, not only the internal casts of - the chambers, but also casts of the interior of the 'canal system' - of the 'intermediate' or 'supplemental skeleton,' and even casts of - the interior of the very fine parallel tubuli which traverse the - proper walls of the chambers. And, as I have remarked elsewhere,[R] - 'such casts place before us far more exact representations of the - configuration of the animal body, and of the connections of its - different parts, than we could obtain even from living specimens by - dissolving away their shells with acid; its several portions being - disposed to heap themselves together in a mass when they lose the - support of the calcareous skeleton.' - -[Footnote Q: The specimens submitted to Dr. Carpenter were taken from a -block of Eozoon rock, obtained in the Petite Nation seigniory, too late -to afford Dr. Dawson an opportunity of examination. They are from the -same horizon as the Grenville specimens.--W. E. L.] - -[Footnote R: _Introduction to the Study of the Foraminifera_, p. 10.] - - "The additional opportunities I have thus enjoyed will be found, - I believe, to account satisfactorily for the differences to be - observed between Dr. Dawson's account of the Eozoon and my own. Had - I been obliged to form my conclusions respecting its structure only - from the specimens submitted to Dr. Dawson, I should very probably - have seen no reason for any but the most complete accordance with - his description: while if Dr. Dawson had enjoyed the advantage of - examining the entire series of preparations which have come under my - own observation, I feel confident that he would have anticipated the - corrections and additions which I now offer. - - "Although the general plan of growth described by Dr. Dawson, and - exhibited in his photographs of vertical sections of the fossil, - is undoubtedly that which is typical of Eozoon, yet I find that - the acervuline mode of growth, also mentioned by Dr. Dawson, very - frequently takes its place in the more superficial parts, where - the chambers, which are arranged in regular tiers in the laminated - portions, are heaped one upon another without any regularity, as is - particularly well shown in some decalcified specimens which I have - myself prepared from the slices last put into my hands. I see no - indication that this departure from the normal type of structure - has resulted from an injury; the transition from the regular to the - irregular mode of increase not being abrupt but gradual. Nor shall I - be disposed to regard it as a monstrosity; since there are many other - Foraminifera in which an originally definite plan of growth gives - place, in a later stage, to a like acervuline piling-up of chambers. - - "In regard to the form and relations of the chambers, I have little - to add to Dr. Dawson's description. The evidence afforded by their - internal casts concurs with that of sections, in showing that the - segments of the sarcode-body, by whose aggregation each layer was - constituted, were but very incompletely divided by shelly partitions; - this incomplete separation (as Dr. Dawson has pointed out) having - its parallel in that of the secondary chambers in Carpenteria. But I - have occasionally met with instances in which the separation of the - chambers has been as complete as it is in Foraminifera generally; and - the communication between them is then established by several narrow - passages exactly corresponding with those which I have described and - figured in Cycloclypeus.[S] - -[Footnote S: _Op. cit._, p. 294.] - - "The mode in which each successive layer originates from the one - which had preceded it, is a question to which my attention has been - a good deal directed; but I do not as yet feel confident that I - have been able to elucidate it completely. There is certainly no - regular system of apertures for the passage of stolons giving origin - to new segments, such as are found in all ordinary Polythalamous - Foraminifera, whether their type of growth be rectilinear, spiral, - or cyclical; and I am disposed to believe that where one layer is - separated from another by nothing else than the proper walls of - the chambers,--which, as I shall presently show, are traversed by - multitudes of minute tubuli giving passage to pseudopodia,--the - coalescence of these pseudopodia on the external surface would - suffice to lay the foundation of a new layer of sarcodic segments. - But where an intermediate or supplemental skeleton, consisting of a - thick layer of solid calcareous shell, has been deposited between - two successive layers, it is obvious that the animal body contained - in the lower layer of chambers must be completely cut off from - that which occupies the upper, unless some special provision exist - for their mutual communication. Such a provision I believe to have - been made by the extension of bands of sarcode, through canals left - in the intermediate skeleton, from the lower to the upper tier of - chambers. For in such sections as happen to have traversed thick - deposits of the intermediate skeleton, there are generally found - passages distinguished from those of the ordinary canal-system by - their broad flat form, their great transverse diameter, and their - non-ramification. One of these passages I have distinctly traced - to a chamber, with the cavity of which it communicated through two - or three apertures in its proper wall; and I think it likely that - I should have been able to trace it at its other extremity into a - chamber of the superjacent tier, had not the plane of the section - passed out of its course. Riband-like casts of these passages are - often to be seen in decalcified specimens, traversing the void spaces - left by the removal of the thickest layers of the intermediate - skeleton. - - "But the organization of a new layer seems to have not unfrequently - taken place in a much more considerable extension of the sarcode-body - of the pre-formed layer; which either folded back its margin - over the surface already consolidated, in a manner somewhat like - that in which the mantle of a Cyprœa doubles back to deposit - the final surface-layer of its shell, or sent upwards wall-like - lamellæ, sometimes of very limited extent, but not unfrequently of - considerable length, which, after traversing the substance of the - shell, like trap-dykes in a bed of sandstone, spread themselves out - over its surface. Such, at least, are the only interpretations I can - put upon the appearances presented by decalcified specimens. For - on the one hand, it is frequently to be observed that two bands of - serpentine (or other infiltrated mineral), which represent two layers - of the original sarcode-body of the animal, approximate to each other - in some part of their course, and come into complete continuity; - so that the upper layer would seem at that part to have had its - origin in the lower. Again, even where these bands are most widely - separated, we find that they are commonly held together by vertical - lamellæ of the same material, sometimes forming mere tongues, but - often running to a considerable length. That these lamellæ have not - been formed by mineral infiltration into accidental fissures in the - shell, but represent corresponding extensions of the sarcode-body, - seems to me to be indicated not merely by the characters of their - surface, but also by the fact that portions of the canal-system may - be occasionally traced into connection with them. - - "Although Dr. Dawson has noticed that some parts of the sections - which he examined present the fine tubulation characteristic of - the shells of the Nummuline Foraminifera, he does not seem to have - recognised the fact, which the sections placed in my hands have - enabled me most satisfactorily to determine,--that the proper - walls of the chambers everywhere present the fine tubulation of - the Nummuline shell; a point of the highest importance in the - determination of the affinities of Eozoon. This tubulation, although - not seen with the clearness with which it is to be discerned in - recent examples of the Nummuline type, is here far better displayed - than it is in the majority of fossil Nummulites, in which the - tubuli have been filled up by the infiltration of calcareous - matter, rendering the shell-substance nearly homogeneous. In Eozoon - these tubuli have been filled up by the infiltration of a mineral - different from that of which the shell is composed, and therefore - not coalescing with it; and the tubular structure is consequently - much more satisfactorily distinguishable. In decalcified specimens, - the free margins of the casts of the chambers are often seen to be - bordered with a delicate white glistening fringe; and when this - fringe is examined with a sufficient magnifying power, it is seen to - be made up of a multitude of extremely delicate aciculi, standing - side by side like the fibres of asbestos. These, it is obvious, are - the internal casts of the fine tubuli which perforated the proper - wall of the chambers, passing directly from its inner to its outer - surface; and their presence in this situation affords the most - satisfactory confirmation of the evidence of that tubulation afforded - by thin sections of the shell-wall. - - "The successive layers, each having its own proper wall, are - often superposed one upon another without the intervention of any - supplemental or intermediate skeleton such as presents itself in - all the more massive forms of the Nummuline series; but a deposit - of this form of shell-substance, readily distinguishable by its - homogeneousness from the finely tubular shell immediately investing - the segments of the sarcode-body, is the source of the great - thickening which the calcareous zones often present in vertical - sections of Eozoon. The presence of this intermediate skeleton has - been correctly indicated by Dr. Dawson; but he does not seem to have - clearly differentiated it from the proper wall of the chambers. - All the tubuli which he has described belong to that canal system - which, as I have shown,[T] is limited in its distribution to the - intermediate skeleton, and is expressly designed to supply a channel - for its nutrition and augmentation. Of this canal system, which - presents most remarkable varieties in dimensions and distribution, we - learn more from the casts presented by decalcified specimens, than - from sections, which only exhibit such parts of it as their plane may - happen to traverse. Illustrations from both sources, giving a more - complete representation of it than Dr. Dawson's figures afford, have - been prepared from the additional specimens placed in my hands. - -[Footnote T: _Op. cit._, pp. 50, 51.] - - "It does not appear to me that the canal system takes its origin - directly from the cavity of the chambers. On the contrary, I believe - that, as in Calcarina (which Dr. Dawson has correctly referred to as - presenting the nearest parallel to it among recent Foraminifera), - they originate in lacunar spaces on the outside of the proper - walls of the chambers, into which the tubuli of those walls open - externally; and that the extensions of the sarcode-body which - occupied them were formed by the coalescence of the pseudopodia - issuing from those tubuli.[U] - -[Footnote U: _Op. cit._, p. 221.] - - "It seems to me worthy of special notice, that the canal system, - wherever displayed in transparent sections, is distinguished by a - yellowish brown coloration, so exactly resembling that which I have - observed in the canal system of recent Foraminifera (as Polystomella - and Calcarina) in which there were remains of the sarcode-body, that - I cannot but believe the infiltrating mineral to have been dyed by - the remains of sarcode still existing in the canals of Eozoon at the - time of its consolidation. If this be the case, the preservation - of this colour seems to indicate that no considerable metamorphic - action has been exerted upon the rock in which this fossil occurs. - And I should draw the same inference from the fact that the organic - structure of the shell is in many instances even more completely - preserved than it usually is in the Nummulites and other Foraminifera - of the Nummulitic limestone of the early Tertiaries. - - "To sum up,--That the _Eozoon_ finds its proper place in the - Foraminiferal series, I conceive to be conclusively proved by its - accordance with the great types of that series, in all the essential - characters of organization;--namely, the structure of the shell - forming the proper wall of the chambers, in which it agrees precisely - with Nummulina and its allies; the presence of an intermediate - skeleton and an elaborate canal system, the disposition of which - reminds us most of Calcarina; a mode of communication of the chambers - when they are most completely separated, which has its exact parallel - in Cycloclypeus; and an ordinary want of completeness of separation - between the chambers, corresponding with that which is characteristic - of Carpenteria. - - "There is no other group of the animal kingdom to which Eozoon - presents the slightest structural resemblance; and to the suggestion - that it may have been of kin to Nullipore, I can offer the most - distinct negative reply, having many years ago carefully studied the - structure of that stony Alga, with which that of Eozoon has nothing - whatever in common. - - "The objections which not unnaturally occur to those familiar with - only the ordinary forms of Foraminifera, as to the admission of - Eozoon into the series, do not appear to me of any force. These have - reference in the first place to the great _size_ of the organism; and - in the second, to its exceptional mode of growth. - - "1. It must be borne in mind that all the Foraminifera normally - increase by the continuous gemmation of new segments from those - previously formed; and that we have, in the existing types, the - greatest diversities in the extent to which this gemmation may - proceed. Thus in the Globigerinæ, whose shells cover to an unknown - thickness the sea bottom of all that portion of the Atlantic Ocean - which is traversed by the Gulf Stream, only eight or ten segments - are ordinarily produced by continuous gemmation; and if new segments - are developed from the last of these, they detach themselves so - as to lay the foundation of independent Globigerinæ. On the other - hand in Cycloclypeus, which is a discoidal structure attaining two - and a quarter inches in diameter, the number of segments formed by - continuous gemmation must be many thousand. Again, the Receptaculites - of the Canadian Silurian rocks, shown by Mr. Salter's drawings[V] - to be a gigantic Orbitolite, attains a diameter of twelve inches; - and if this were to increase by vertical as well as by horizontal - gemmation (after the manner of Tinoporus or Orbitoides) so that one - discoidal layer would be piled on another, it would form a mass - equalling Eozoon in its ordinary dimensions. To say, therefore, that - Eozoon cannot belong to the Foraminifera on account of its gigantic - size, is much as if a botanist who had only studied plants and - shrubs were to refuse to admit a tree into the same category. The - very same continuous gemmation which has produced an Eozoon would - produce an equal mass of independent Globigerinæ, if after eight - or ten repetitions of the process, the new segments were to detach - themselves. - -[Footnote V: _First Decade of Canadian Fossils_, pl. x.] - - "It is to be remembered, moreover, that the largest masses of sponges - are formed by continuous gemmation from an original Rhizopod segment; - and that there is no _à priori_ reason why a Foraminiferal organism - should not attain the same dimensions as a Poriferal one,--the - intimate relationship of the two groups, notwithstanding the - difference between their skeletons, being unquestionable. - - "2. The difficulty arising from the zoophytic plan of growth of - Eozoon is at once disposed of by the fact that we have in the recent - Polytrema (as I have shown, _op. cit._, p. 235) an organism nearly - allied in all essential points of structure to Rotalia, yet no - less aberrant in its plan of growth, having been ranked by Lamarck - among the Millepores. And it appears to me that Eozoon takes its - place quite as naturally in the Nummuline series as Polytrema in - the Rotaline. As we are led from the typical Rotalia, through the - less regular Planorbulina, to Tinoporus, in which the chambers are - piled up vertically, as well as multiplied horizontally, and thence - pass by an easy gradation to Polytrema, in which all regularity of - external form is lost; so may we pass from the typical Operculina or - Nummulina, through Heterostegina and Cycloclypeus to Orbitoides, in - which, as in Tinoporus, the chambers multiply both by horizontal and - by vertical gemmation; and from Orbitoides to Eozoon the transition - is scarcely more abrupt than from Tinoporus to Polytrema. - - "The general acceptance, by the most competent judges, of my views - respecting the primary value of the characters furnished by the - intimate structure of the shell, and the very subordinate value - of plan of growth, in the determination of the affinities of - Foraminifera, renders it unnecessary that I should dwell further on - my reasons for unhesitatingly affirming the Nummuline affinities of - Eozoon from the microscopic appearances presented by the proper wall - of its chambers, notwithstanding its very aberrant peculiarities; - and I cannot but feel it to be a feature of peculiar interest in - geological inquiry, that the true relations of by far the earliest - fossil yet known should be determinable by the comparison of a - portion which the smallest pin's head would cover, with organisms at - present existing." - - -(C.) Note on Specimens From Long Lake and Wentworth. - -[_Journal of Geological Society_, August, 1867.] - - "Specimens from Long Lake, in the collection of the Geological - Survey of Canada, exhibit white crystalline limestone with light - green compact or septariiform[W] serpentine, and much resemble some - of the serpentine limestones of Grenville. Under the microscope the - calcareous matter presents a delicate areolated appearance, without - lamination; but it is not an example of acervuline Eozoon, but rather - of fragments of such a structure, confusedly aggregated together, and - having the interstices and cell-cavities filled with serpentine. I - have not found in any of these fragments a canal system similar to - that of Eozoon Canadense, though there are casts of large stolons, - and, under a high power, the calcareous matter shows in many places - the peculiar granular or cellular appearance which is one of the - characters of the supplemental skeleton of that species. In a few - places a tubulated cell-wall is preserved, with structure similar to - that of Eozoon Canadense. - -[Footnote W: I use the term "septariiform" to denote the _curdled_ -appearance so often presented by the Laurentian serpentine.] - - "Specimens of Laurentian limestone from Wentworth, in the collection - of the Geological Survey, exhibit many rounded silicious bodies, some - of which are apparently grains of sand, or small pebbles; but others, - especially when freed from the calcareous matter by a dilute acid, - appear as rounded bodies, with rough surfaces, either separate or - aggregated in lines or groups, and having minute vermicular processes - projecting from their surfaces. At first sight these suggest the - idea of spicules; but I think it on the whole more likely that - they are casts of cavities and tubes belonging to some calcareous - Foraminiferal organism which has disappeared. Similar bodies, found - in the limestone of Bavaria, have been described by Gümbel, who - interprets them in the same way. They may also be compared with the - silicious bodies mentioned in a former paper as occurring in the - loganite filling the chambers of specimens of _Eozoon_ from Burgess." - - These specimens will be more fully referred to under Chapter VI. - - -(D.) Additional Structural Facts. - - I may mention here a peculiar and interesting structure which has - been detected in one of my specimens while these sheets were passing - through the press. It is an abnormal thickening of the calcareous - wall, extending across several layers, and perforated with large - parallel cylindrical canals, filled with dolomite, and running in - the direction of the laminæ; the intervening calcite being traversed - by a very fine and delicate canal system. It makes a nearer approach - to some of the Stromatoporæ mentioned in Chapter VI. than any other - Laurentian structure hitherto observed, and may be either an abnormal - growth of Eozoon, consequent on some injury, or a parasitic mass of - some Stromatoporoid organism overgrown by the laminæ of the fossil. - The structure of the dolomite in this specimen indicates that it - first lined the canals, and afterward filled them; an appearance - which I have also observed recently in the larger canals filled - with serpentine (Plate VIII., fig. 5). The cut below is an attempt, - only partially successful, to show the Amœba-like appearance, when - magnified, of the casts of the chambers of Eozoon, as seen on the - decalcified surface of a specimen broken parallel to the laminæ. - -[Illustration: Fig. 21_a_.] - -[Illustration: - Plate V. - -_Nature-print of Eozoon, showing laminated, acervuline, and fragmental - portions._ - -This is printed from an electrotype taken from an etched slab of -Eozoon, and not touched with a graver except to remedy some accidental -flaws in the plate. The diagonal white line marks the course of a -calcite vein.] - - - - -CHAPTER V. - -THE PRESERVATION OF EOZOON. - - -Perhaps nothing excites more scepticism as to this ancient fossil -than the prejudice existing among geologists that no organism can be -preserved in rocks so highly metamorphic as those of the Laurentian -series. I call this a prejudice, because any one who makes the -microscopic structure of rocks and fossils a special study, soon learns -that fossils undergo the most remarkable and complete chemical changes -without losing their minute structure, and that calcareous rocks if -once fossiliferous are hardly ever so much altered as to lose all -trace of the organisms which they contained, while it is a most common -occurrence to find highly crystalline rocks of this kind abounding in -fossils preserved as to their minute structure. - -Let us, however, look at the precise conditions under which this takes -place. - -When calcareous fossils of irregular surface and porous or cellular -texture, such as Eozoon was or corals were and are, become imbedded -in clay, marl, or other soft sediment, they can be washed out and -recovered in a condition similar to that of recent specimens, except -that their pores or cells if open may be filled with the material of -the matrix, or if not so open that they can be thus filled, they may be -more or less incrusted with mineral deposits introduced by water, or -may even be completely filled up in this way. But if such fossils are -contained in hard rocks, they usually fail, when these are broken, to -show their external surfaces, and, breaking across with the containing -rock, they exhibit their internal structure merely,--and this more -or less distinctly, according to the manner in which their cells or -cavities have been filled. Here the microscope becomes of essential -service, especially when the structures are minute. A fragment of -fossil wood which to the naked eye is nothing but a dark stone, or a -coral which is merely a piece of gray or coloured marble, or a specimen -of common crystalline limestone made up originally of coral fragments, -presents, when sliced and magnified, the most perfect and beautiful -structure. In such cases it will be found that ordinarily the original -substance of the fossil remains, in a more or less altered state. Wood -may be represented by dark lines of coaly matter, or coral by its -white or transparent calcareous laminæ; while the material which has -been introduced and which fills the cavities may so differ in colour, -transparency, or crystalline structure, as to act differently on -light, and so reveal the structure. These fillings are very curious. -Sometimes they are mere earthy or muddy matter. Sometimes they are -pure and transparent and crystalline. Often they are stained with -oxide of iron or coaly matter. They may consist of carbonate of lime, -silica or silicates, sulphate of baryta, oxides of iron, carbonate of -iron, iron pyrite, or sulphides of copper or lead, all of which are -common materials. They are sometimes so complicated that I have seen -even the minute cells of woody structures, each with several bands of -differently coloured materials deposited in succession, like the coats -of an onyx agate. - -A further stage of mineralization occurs when the substance of the -organism is altogether removed and replaced by foreign matter, either -little by little, or by being entirely dissolved or decomposed, -leaving a cavity to be filled by infiltration. In this state are some -silicified woods, and those corals which have been not filled with but -converted into silica, and can thus sometimes be obtained entire and -perfect by the solution in an acid of the containing limestone, or by -its removal in weathering. In this state are the beautiful silicified -corals obtained from the corniferous limestone of Lake Erie. It may be -well to present to the eye these different stages of fossilization. I -have attempted to do this in fig. 22, taking a tabulate coral of the -genus Favosites for an example, and supposing the materials employed to -be calcite and silica. Precisely the same illustration would apply to a -piece of wood, except that the cell-wall would be carbonaceous matter -instead of carbonate of lime. In this figure the dotted parts represent -carbonate of lime, the diagonally shaded parts silica or a silicate. -Thus we have, in the natural state, the walls of carbonate of lime -and the cavities empty. When fossilized the cavities may be merely -filled with carbonate of lime, or they may be filled with silica; or -the walls themselves may be replaced by silica and the cavities may -remain filled with carbonate of lime; or both the walls and cavities -may be represented by or filled with silica or silicates. The ordinary -specimens of Eozoon are in the third of these stages, though some exist -in the second, and I have reason to believe that some have reached to -the fifth. I have not met with any in the fourth stage, though this is -not uncommon in Silurian and Devonian fossils. - -[Illustration: Fig. 22. _Diagram showing different States of -Fossilization of a Cell of a Tabulate Coral._ - -(_a._) Natural condition--walls calcite, cell empty. (_b._) Walls -calcite, cell filled with the same. (_c._) Walls calcite, cell filled -with silica or silicate. (_d._) Walls silicified, cell filled with -calcite. (_e._) Walls silicified, cell filled with silica or silicate.] - -With regard to the calcareous organisms with which we have now to do, -when these are imbedded in pure limestone and filled with the same, so -that the whole rock, fossils and all, is identical in composition, and -when metamorphic action has caused the whole to become crystalline, -and perhaps removed the remains of carbonaceous matter, it may be very -difficult to detect any traces of fossils. But even in this case -careful management of light may reveal indications of structure, as in -some specimens of Eozoon described by the writer and Dr. Carpenter. In -many cases, however, even where the limestones have become perfectly -crystalline, and the cleavage planes cut freely across the fossils, -these exhibit their forms and minute structure in great perfection. -This is the case in many of the Lower Silurian limestones of Canada, -as I have elsewhere shown.[X] The gray crystalline Trenton limestone -of Montreal, used as a building stone, is an excellent illustration -of this. To the naked eye it is a gray marble composed of cleavable -crystals; but when examined in thin slices, it shows its organic -fragments in the greatest perfection, and all the minute structures -are perfectly marked out by delicate carbonaceous lines. The only -exception in this limestone is in the case of the Crinoids, in which -the cellular structure is filled with transparent calc-spar, perfectly -identical with the original solid matter, so that they appear solid -and homogeneous, and can be recognised only by their external forms. -The specimen represented in fig. 23, is a mass of Corals, Bryozoa, and -Crinoids, and shows these under a low power, as represented in the -figure; but to the naked eye it is merely a gray crystalline limestone. -The specimen represented in fig. 24 shows the Laurentian Eozoon in a -similar state of preservation. It is from a sketch by Dr. Carpenter, -and shows the delicate canals partly filled with calcite as clear and -colourless as that of the shell itself, and distinguishable only by -careful management of the light. - -[Footnote X: _Canadian Naturalist_, 1859; Microscopic Structure of -Canadian Limestones.] - -[Illustration: Fig. 23. _Slice of Crystalline Lower Silurian Limestone; -showing Crinoids, Bryozoa, and Corals in fragments._] - -[Illustration: Fig. 24. _Wall of Eozoon penetrated with Canals. The -unshaded portions filled with Calcite._ (_After Carpenter._)] - -In the case of recent and fossil Foraminifers, these--when not so -little mineralized that their chambers are empty, or only partially -filled, which is sometimes the case even with Eocene Nummulites -and Cretaceous forms of smaller size,--are very frequently filled -solid with calcareous matter, and as Dr. Carpenter well remarks, -even well preserved Tertiary Nummulites in this state often fail -greatly in showing their structures, though in the same condition -they occasionally show these in great perfection. Among the finest -I have seen are specimens from the Mount of Olives (fig. 19), and -Dr. Carpenter mentions as equally good those of the London clay of -Bracklesham. But in no condition do modern Foraminifera or those of -the Tertiary and Mesozoic rocks appear in greater perfection than when -filled with the hydrous silicate of iron and potash called glauconite, -and which gives by the abundance of its little bottle-green concretions -the name of "green-sand" to formations of this age both in Europe and -America. In some beds of green-sand every grain seems to have been -moulded into the interior of a microscopic shell, and has retained -its form after the frail envelope has been removed. In some cases the -glauconite has not only filled the chambers but has penetrated the -fine tubulation, and when the shell is removed, either naturally or -by the action of an acid, these project in minute needles or bundles -of threads from the surface of the cast. It is in the warmer seas, -and especially in the bed of the Ægean and of the Gulf Stream, that -such specimens are now most usually found. If we ask why this mineral -glauconite should be associated with Foraminiferal shells, the answer -is that they are both products of one kind of locality. The same sea -bottoms in which Foraminifera most abound are also those in which for -some unknown chemical reason glauconite is deposited. Hence no doubt -the association of this mineral with the great Foraminiferal formation -of the chalk. It is indeed by no means unlikely that the selection -by these creatures of the pure carbonate of lime from the sea-water -or its minute plants, may be the means of setting free the silica, -iron, and potash, in a state suitable for their combination. Similar -silicates are found associated with marine limestones, as far back as -the Silurian age; and Dr. Sterry Hunt, than whom no one can be a better -authority on chemical geology, has argued on chemical grounds that the -occurrence of serpentine with the remains of Eozoon is an association -of the same character. - -However this may be, the infiltration of the pores of Eozoon with -serpentine and other silicates has evidently been one main means of -the preservation of its structure. When so infiltrated no metamorphism -short of the complete fusion of the containing rock could obliterate -the minutest points of structure; and that such fusion has not -occurred, the preservation in the Laurentian rocks of the most delicate -lamination of the beds shows conclusively; while, as already stated, it -can be shown that the alteration which has occurred might have taken -place at a temperature far short of that necessary to fuse limestone. -Thus has it happened that these most ancient fossils have been -handed down to our time in a state of preservation comparable, as Dr. -Carpenter states, to that of the best preserved fossil Foraminifera -from the more recent formations that have come under his observation in -the course of all his long experience. - -Let us now look more minutely at the nature of the typical specimens -of Eozoon as originally observed and described, and then turn to those -preserved in other ways, or more or less destroyed and defaced. Taking -a polished specimen from Petite Nation, like that delineated in Plate -V., we find the shell represented by white limestone, and the chambers -by light green serpentine. By acting on the surface with a dilute -acid we etch out the calcareous part, leaving a cast in serpentine -of the cavities occupied by the soft parts; and when this is done in -polished slices these may be made to print their own characters on -paper, as has actually been done in the case of Plate V., which is an -electrotype taken from an actual specimen, and shows both the laminated -and acervuline parts of the fossil. If the process of decalcification -has been carefully executed, we find in the excavated spaces delicate -ramifying processes of opaque serpentine or transparent dolomite, which -were originally imbedded in the calcareous substance, and which are -often of extreme fineness and complexity. (Plate VI. and fig. 10.) -These are casts of the canals which traversed the shell when still -inhabited by the animal. In some well preserved specimens we find the -original cell-wall represented by a delicate white film, which under -the microscope shows minute needle-like parallel processes representing -its still finer tubuli. It is evident that to have filled these tubuli -the serpentine must have been introduced in a state of actual solution, -and must have carried with it no foreign impurities. Consequently we -find that in the chambers themselves the serpentine is pure; and if we -examine it under polarized light, we see that it presents a singularly -curdled or irregularly laminated appearance, which I have designated -under the name septariiform, as if it had an imperfectly crystalline -structure, and had been deposited in irregular laminæ, beginning at -the sides of the chambers, and filling them toward the middle, and -had afterward been cracked by shrinkage, and the cracks filled with a -second deposit of serpentine. Now, serpentine is a hydrous silicate of -magnesia, and all that we need to suppose is that in the deposits of -the Laurentian sea magnesia was present instead of iron and potash, -and we can understand that the Laurentian fossil has been petrified -by infiltration with serpentine, as more modern Foraminifera have -been with glauconite, which, though it usually has little magnesia, -often has a considerable percentage of alumina. Further, in specimens -of Eozoon from Burgess, the filling mineral is loganite, a compound -of silica, alumina, magnesia and iron, with water, and in certain -Silurian limestones from New Brunswick and Wales, in which the delicate -microscopic pores of the skeletons of stalked star-fishes or Crinoids -have been filled with mineral deposits, so that when decalcified -these are most beautifully represented by their casts, Dr. Hunt has -proved the filling mineral to be a silicate of alumina, iron, magnesia -and potash, intermediate between serpentine and glauconite. We have, -therefore, ample warrant for adhering to Dr. Hunt's conclusion that -the Laurentian serpentine was deposited under conditions similar to -those of the modern green-sand. Indeed, independently of Eozoon, it is -impossible that any geologist who has studied the manner in which this -mineral is associated with the Laurentian limestones could believe it -to have been formed in any other way. Nor need we be astonished at -the fineness of the infiltration by which these minute tubes, perhaps -1/10000 of an inch in diameter, are filled with mineral matter. The -micro-geologist well knows how, in more modern deposits, the finest -pores of fossils are filled, and that mineral matter in solution -can penetrate the smallest openings that the microscope can detect. -Wherever the fluids of the living body can penetrate, there also -mineral substances can be carried, and this natural injection, effected -under great pressure and with the advantage of ample time, can surpass -any of the feats of the anatomical manipulator. Fig. 25 represents -a microscopic joint of a Crinoid from the Upper Silurian of New -Brunswick, injected with the hydrous silicate already referred to, and -fig. 26 shows a microscopic chambered or spiral shell, from a Welsh -Silurian limestone, with its cavities filled with a similar substance. - -[Illustration: Fig. 25. _Joint of a Crinoid, having its pores injected -with a Hydrous Silicate._ - -Upper Silurian Limestone, Pole Hill, New Brunswick. Magnified 25 -diameters.] - -[Illustration: Fig. 26. _Shell from a Silurian Limestone, Wales; its -cavity filled with a Hydrous Silicate._ - -Magnified 25 diameters.] - -It is only necessary to refer to the attempts which have been made to -explain by merely mineral deposits the occurrence of the serpentine -in the canals and chambers of Eozoon, and its presenting the form it -does, to see that this is the case. Prof. Rowney, for example, to avoid -the force of the argument from the canal system, is constrained to -imagine that the whole mass has at one time been serpentine, and that -this has been partially washed away, and replaced by calcite. If so, -whence the deposition of the supposed mass of serpentine, which has to -be accounted for in this way as well as in the other? How did it happen -to be eroded into so regular chambers, leaving intermediate floors and -partitions. And, more wonderful still, how did the regular dendritic -bundles, so delicate that they are removed by a breath, remain perfect, -and endure until they were imbedded in calcareous spar? Further, how -does it happen that in some specimens serpentine and pyroxene seem to -have encroached upon the structure, as if they and not calcite were the -eroding minerals? How any one who has looked at the structures can for -a moment imagine such a possibility, it is difficult to understand. If -we could suppose the serpentine to have been originally deposited as -a cellular or laminated mass, and its cavities filled with calcite in -a gelatinous or semi-fluid state, we might suppose the fine processes -of serpentine to have grown outward into these cavities in the mass, -as fibres of oxide of iron or manganese have grown in the silica of -moss-agate; but this theory would be encompassed with nearly as great -mechanical and chemical difficulties. The only rational view that any -one can take of the process is, that the calcareous matter was the -original substance, and that it had delicate tubes traversing it which -became injected with serpentine. The same explanation, and no other, -will suffice for those delicate cell-walls, penetrated by innumerable -threads of serpentine, which must have been injected into pores. It is -true that there are in some of the specimens cracks filled with fibrous -serpentine or chrysotile, but these traverse the mass in irregular -directions, and they consist of closely packed angular prisms, -instead of a matrix of limestone penetrated by cylindrical threads of -serpentine. (Fig. 27.) Here I must once for all protest against the -tendency of some opponents of Eozoon to confound these structures and -the canal system of Eozoon with the acicular crystals, and dendritic -or coralloidal forms, observed in some minerals. It is easy to make -such comparisons appear plausible to the uninitiated, but practised -observers cannot be so deceived, the differences are too marked and -essential. In illustration of this, I may refer to the highly magnified -canals in figs. 28 and 29. Further, it is evident from the examination -of the specimens, that the chrysotile veins, penetrating as they often -do diagonally or transversely across both chambers and walls, must have -originated subsequently to the origin and hardening of the rock and its -fossils, and result from aqueous deposition of fibrous serpentine in -cracks which traverse alike the fossils and their matrix. In specimens -now before me, nothing can be more plain than this entire independence -of the shining silky veins of fibrous serpentine, and the fact of their -having been formed subsequently to the fossilization of the Eozoon; -since they can be seen to run across the lamination, and to branch off -irregularly in lines altogether distinct from the structure. This, -while it shows that these veins have no connection with the fossil, -shows also that the latter was an original ingredient of the beds when -deposited, and not a product of subsequent concretionary action. - -[Illustration: Fig. 27. _Diagram showing the different appearances -of the cell-wall of Eozoon and of a vein of Chrysotile, when highly -magnified._] - -[Illustration: Fig. 28. _Casts of Canals of Eozoon in Serpentine, -decalcified and highly magnified._] - -[Illustration: Fig. 29. _Canals of Eozoon._ - -Highly magnified.] - -Taking the specimens preserved by serpentine as typical, we now turn -to certain other and, in some respects, less characteristic specimens, -which are nevertheless very instructive. At the Calumet some of -the masses are partly filled with serpentine and partly with white -pyroxene, an anhydrous silicate of lime and magnesia. The two minerals -can readily be distinguished when viewed with polarized light; and in -some slices I have seen part of a chamber or group of canals filled -with serpentine and part with pyroxene. In this case the pyroxene -or the materials which now compose it, must have been introduced by -infiltration, as well as the serpentine. This is the more remarkable as -pyroxene is most usually found as an ingredient of igneous rocks; but -Dr. Hunt has shown that in the Laurentian limestones and also in veins -traversing them, it occurs under conditions which imply its deposition -from water, either cold or warm. Gümbel remarks on this:--"Hunt, in -a very ingenious manner, compares this formation and deposition of -serpentine, pyroxene, and loganite, with that of glauconite, whose -formation has gone on uninterruptedly from the Silurian to the Tertiary -period, and is even now taking place in the depths of the sea; it being -well known that Ehrenberg and others have already shown that many of -the grains of glauconite are casts of the interior of foraminiferal -shells. In the light of this comparison, the notion that the serpentine -and such like minerals of the primitive limestones have been formed, -in a similar manner, in the chambers of Eozoic Foraminifera, loses any -traces of improbability which it might at first seem to possess." - -In many parts of the skeleton of Eozoon, and even in the best -infiltrated serpentine specimens, there are portions of the cell-wall -and canal system which have been filled with calcareous spar or with -dolomite, so similar to the skeleton that it can be detected only under -the most favourable lights and with great care. (Fig. 24, _supra_.) -The same phenomena may be observed in joints of Crinoids from the -Palæozoic rocks, and they constitute proofs of organic origin even -more irrefragable than the filling with serpentine. Dr. Carpenter has -recently, in replying to the objections of Mr. Carter, made excellent -use of this feature of the preservation of Eozoon. It is further to -be remarked that in all the specimens of true Eozoon, as well as -in many other calcareous fossils preserved in ancient rocks, the -calcareous matter, even when its minute structures are not preserved -or are obscured, presents a minutely granular or curdled appearance, -arising no doubt from the original presence of organic matter, and not -recognised in purely inorganic calcite. - -Another style of these remarkable fossils is that of the Burgess -specimens. In these the walls have been changed into dolomite -or magnesian limestone, and the canals seem to have been wholly -obliterated, so that only the laminated structure remains. The material -filling the chambers is also an aluminous silicate named loganite; and -this seems to have been introduced, not so much in solution, as in -the state of muddy slime, since it contains foreign bodies, as grains -of sand and little groups of silicious concretions, some of which are -not unlikely casts of the interior of minute foraminiferal shells -contemporary with Eozoon, and will be noticed in the sequel. - -[Illustration: Fig. 30. _Eozoon from Tudor._ - -Two-thirds natural size. (_a._) Tubuli. (_b._) Canals. Magnified. _a_ -and _b_ from another specimen.] - -Still another mode of occurrence is presented by a remarkable specimen -from Tudor in Ontario, and from beds probably on the horizon of the -Upper Laurentian or Huronian.[Y] It occurs in a rock scarcely at all -metamorphic, and the fossil is represented by white carbonate of lime, -while the containing matrix is a dark-coloured coarse limestone. In -this specimen the material filling the chambers has not penetrated -the canals except in a few places, where they appear filled with dark -carbonaceous matter. In mode of preservation these Tudor specimens -much resemble the ordinary fossils of the Silurian rocks. One of -the specimens in the collection of the Geological Survey (fig. 30) -presents a clavate form, as if it had been a detached individual -supported on one end at the bottom of the sea. It shows, as does -also the original Calumet specimen, the septa approaching each other -and coalescing at the margin of the form, where there were probably -orifices communicating with the exterior. Other specimens of fragmental -Eozoon from the Petite Nation localities have their canals filled with -dolomite, which probably penetrated them after they were broken up -and imbedded in the rock. I have ascertained with respect to these -fragments of Eozoon, that they occur abundantly in certain layers of -the Laurentian limestone, beds of some thickness being in great part -made up of them, and coarse and fine fragments occur in alternate -layers, like the broken corals in some Silurian limestones. - -[Footnote Y: See Note B, Chap. III.] - -Finally, on this part of the subject, careful observation of many -specimens of Laurentian limestone which present no trace of Eozoon -when viewed by the naked eye, and no evidence of structure when acted -on with acids, are nevertheless organic, and consist of fragments -of Eozoon, and possibly of other organisms, not infiltrated with -silicates, but only with carbonate of lime, and consequently revealing -only obscure indications of their minute structure. I have satisfied -myself of this by long and patient investigations, which scarcely admit -of any adequate representation, either by words or figures. - -Every worker in those applications of the microscope to geological -specimens which have been termed micro-geology, is familiar with the -fact that crystalline forces and mechanical movements of material -often play the most fantastic tricks with fossilized organic matter. -In fossil woods, for example, we often have the tissues disorganized, -with radiating crystallizations of calcite and little spherical -concretions of quartz, or disseminated cubes and grains of pyrite, -or little veins filled with sulphate of barium or other minerals. We -need not, therefore, be surprised to find that in the venerable rocks -containing Eozoon, such things occur in the more highly crystalline -parts of the limestones, and even in some still showing traces of -the fossil. We find many disseminated crystals of magnetite, pyrite, -spinel, mica, and other minerals, curiously curved prisms of vermicular -mica, bundles of aciculi of tremolite and similar substances, veins of -calcite and crysolite or fibrous serpentine, which often traverse the -best specimens. Where these occur abundantly we usually find no organic -structures remaining, or if they exist they are in a very defective -state of preservation. Even in specimens presenting the lamination of -Eozoon to the naked eye, these crystalline actions have often destroyed -the minute structure; and I fear that some microscopists have been -victimised by having under their consideration only specimens in which -the actual characters had been too much defaced to be discernible. I -must here state that I have found some of the specimens sold under -the name of Eozoon Canadense by dealers in microscopical objects to -be almost or quite worthless, being destitute of any good structure, -and often merely pieces of Laurentian limestone with serpentine -grains only. I fear that the circulation of such specimens has done -much to cause scepticism as to the Foraminiferal nature of Eozoon. No -mistake can be greater than to suppose that any and every specimen -of Laurentian limestone must contain Eozoon. More especially have -I hitherto failed to detect traces of it in those carbonaceous or -graphitic limestones which are so very abundant in the Laurentian -country. Perhaps where vegetable matter was very abundant Eozoon -did not thrive, or on the other hand the growth of Eozoon may have -diminished the quantity of vegetable matter. It is also to be observed -that much compression and distortion have occurred in the beds of -Laurentian limestone and their contained fossils, and also that the -specimens are often broken by faults, some of which are so small as to -appear only on microscopic examination, and to shift the plates of the -fossil just as if they were beds of rock. This, though it sometimes -produces puzzling appearances, is an evidence that the fossils were -hard and brittle when this faulting took place, and is consequently -an additional proof of their extraneous origin. In some specimens it -would seem that the lower and older part of the fossil had been wholly -converted into serpentine or pyroxene, or had so nearly experienced -this change that only small parts of the calcareous wall can be -recognised. These portions correspond with fossil woods altogether -silicified, not only by the filling of the cells, but also by the -conversion of the walls into silica. I have specimens which manifestly -show the transition from the ordinary condition of filling with -serpentine to one in which the cell-walls are represented obscurely by -one shade of this mineral and the cavities by another. - -The above considerations as to mode of preservation of Eozoon concur -with those in previous chapters in showing its oceanic character; -but the ocean of the Eozoic period may not have been so deep as at -present, and its waters were probably warm and well stocked with -mineral matters derived from the newly formed land, or from hot springs -in its own bottom. On this point the interesting investigations of -Dr. Hunt with reference to the chemical conditions of the Silurian -seas, allow us to suppose that the Laurentian ocean may have been much -more richly stored, more especially with salts of lime and magnesia, -than that of subsequent times. Hence the conditions of warmth, light, -and nutriment, required by such gigantic Protozoans would all be -present, and hence, also no doubt, some of the peculiarities of its -mineralization. - - -NOTES TO CHAPTER V. - - -(A.) Dr. Sterry Hunt on the Mineralogy of Eozoon and the containing -Rocks. - - It was fortunate for the recognition of Eozoon that Dr. Hunt had, - before its discovery, made so thorough researches into the chemistry - of the Laurentian series, and was prepared to show the chemical - possibilities of the preservation of fossils in these ancient - deposits. The following able summary of his views was appended to the - original description of the fossil in the _Journal of the Geological - Society_. - - "The details of structure have been preserved by the introduction - of certain mineral silicates, which have not only filled up the - chambers, cells, and canals left vacant by the disappearance of the - animal matter, but have in very many cases been injected into the - tubuli, filling even their smallest ramifications. These silicates - have thus taken the place of the original sarcode, while the - calcareous septa remain. It will then be understood that when the - replacement of the Eozoon by silicates is spoken of, this is to be - understood of the soft parts only; since the calcareous skeleton is - preserved, in most cases, without any alteration. The vacant spaces - left by the decay of the sarcode may be supposed to have been filled - by a process of infiltration, in which the silicates were deposited - from solution in water, like the silica which fills up the pores of - wood in the process of silicification. The replacing silicates, so - far as yet observed, are a white pyroxene, a pale green serpentine, - and a dark green alumino-magnesian mineral, which is allied in - composition to chlorite and to pyrosclerite, and which I have - referred to loganite. The calcareous septa in the last case are found - to be dolomitic, but in the other instances are nearly pure carbonate - of lime. The relations of the carbonate and the silicates are well - seen in thin sections under the microscope, especially by polarized - light. The calcite, dolomite, and pyroxene exhibit their crystalline - structure to the unaided eye; and the serpentine and loganite are - also seen to be crystalline when examined with the microscope. When - portions of the fossil are submitted to the action of an acid, the - carbonate of lime is dissolved, and a coherent mass of serpentine is - obtained, which is a perfect cast of the soft parts of the Eozoon. - The form of the sarcode which filled the chambers and cells is - beautifully shown, as well as the connecting canals and the groups - of tubuli; these latter are seen in great perfection upon surfaces - from which the carbonate of lime has been partially dissolved. Their - preservation is generally most complete when the replacing mineral is - serpentine, although very perfect specimens are sometimes found in - pyroxene. The crystallization of the latter mineral appears, however, - in most cases to have disturbed the calcareous septa. - - "Serpentine and pyroxene are generally associated in these specimens, - as if their disposition had marked different stages of a continuous - process. At the Calumet, one specimen of the fossil exhibits the - whole of the sarcode replaced by serpentine; while, in another one - from the same locality, a layer of pale green translucent serpentine - occurs in immediate contact with the white pyroxene. The calcareous - septa in this specimen are very thin, and are transverse to the plane - of contact of the two minerals; yet they are seen to traverse both - the pyroxene and the serpentine without any interruption or change. - Some sections exhibit these two minerals filling adjacent cells, - or even portions of the same cell, a clear line of division being - visible between them. In the specimens from Grenville on the other - hand, it would seem as if the development of the Eozoon (considerable - masses of which were replaced by pyroxene) had been interrupted, and - that a second growth of the animal, which was replaced by serpentine, - had taken place upon the older masses, filling up their interstices." - - [Details of chemical composition are then given.] - - "When examined under the microscope, the loganite which replaces the - Eozoon of Burgess shows traces of cleavage-lines, which indicate a - crystalline structure. The grains of insoluble matter found in the - analysis, chiefly of quartz-sand, are distinctly seen as foreign - bodies imbedded in the mass, which is moreover marked by lines - apparently due to cracks formed by a shrinking of the silicate, and - subsequently filled by a further infiltration of the same material. - This arrangement resembles on a minute scale that of septaria. - Similar appearances are also observed in the serpentine which - replaces the Eozoon of Grenville, and also in a massive serpentine - from Burgess, resembling this, and enclosing fragments of the fossil. - In both of these specimens also grains of mechanical impurities are - detected by the microscope; they are however, rarer than in the - loganite of Burgess. - - "From the above facts it may be concluded that the various silicates - which now constitute pyroxene, serpentine, and loganite were directly - deposited in waters in the midst of which the Eozoon was still - growing, or had only recently perished; and that these silicates - penetrated, enclosed, and preserved the calcareous structure - precisely as carbonate of lime might have done. The association - of the silicates with the Eozoon is only accidental; and large - quantities of them, deposited at the same time, include no organic - remains. Thus, for example, there are found associated with the - Eozoon limestones of Grenville, massive layers and concretions of - pure serpentine; and a serpentine from Burgess has already been - mentioned as containing only small broken fragments of the fossil. - In like manner large masses of white pyroxene, often surrounded - by serpentine, both of which are destitute of traces of organic - structure, are found in the limestone at the Calumet. In some cases, - however, the crystallization of the pyroxene has given rise to - considerable cleavage-planes, and has thus obliterated the organic - structures from masses which, judging from portions visible here and - there, appear to have been at one time penetrated by the calcareous - plates of Eozoon. Small irregular veins of crystalline calcite, and - of serpentine, are found to traverse such pyroxene masses in the - Eozoon limestone of Grenville. - - "It appears that great beds of the Laurentian limestones are - composed of the ruins of the Eozoon. These rocks, which are white, - crystalline, and mingled with pale green serpentine, are similar in - aspect to many of the so-called primary limestones of other regions. - In most cases the limestones are non-magnesian, but one of them - from Grenville was found to be dolomitic. The accompanying strata - often present finely crystallized pyroxene, hornblende, phlogopite, - apatite, and other minerals. These observations bring the formation - of silicious minerals face to face with life, and show that their - generation was not incompatible with the contemporaneous existence - and the preservation of organic forms. They confirm, moreover, the - view which I some years since put forward, that these silicated - minerals have been formed, not by subsequent metamorphism in - deeply buried sediments, but by reactions going on at the earth's - surface.[Z] In support of this view, I have elsewhere referred to - the deposition of silicates of lime, magnesia, and iron from natural - waters, to the great beds of sepiolite in the unaltered Tertiary - strata of Europe; to the contemporaneous formation of neolite (an - aluimino-magnesian silicate related to loganite and chlorite in - composition); and to glauconite, which occurs not only in Secondary, - Tertiary, and Recent deposits, but also, as I have shown, in Lower - Silurian strata.[AA] This hydrous silicate of protoxide of iron - and potash, which sometimes includes a considerable proportion of - alumina in its composition, has been observed by Ehrenberg, Mantell, - and Bailey, associated with organic forms in a manner which seems - identical with that in which pyroxene, serpentine, and loganite - occur with the Eozoon in the Laurentian limestones. According to the - first of these observers, the grains of green-sand, or glauconite, - from the Tertiary limestone of Alabama, are casts of the interior - of Polythalamia, the glauconite having filled them by 'a species of - natural injection, which is often so perfect that not only the large - and coarse cells, but also the very finest canals of the cell-walls - and all their connecting tubes, are thus petrified and separately - exhibited.' Bailey confirmed these observations, and extended them. - He found in various Cretaceous and Tertiary limestones of the United - States, casts in glauconite, not only of _Foraminifera_, but of - spines of _Echinus_, and of the cavities of corals. Besides, there - were numerous red, green, and white casts of minute anastomosing - tubuli, which, according to Bailey, resemble the casts of the holes - made by burrowing sponges (_Cliona_) and worms. These forms are seen - after the dissolving of the carbonate of lime by a dilute acid. - He found, moreover, similar casts of _Foraminifera_, of minute - mollusks, and of branching tubuli, in mud obtained from soundings in - the Gulf Stream, and concluded that the deposition of glauconite is - still going on in the depths of the sea.[AB] Pourtales has followed - up these investigations on the recent formation of glauconite in - the Gulf Stream waters. He has observed its deposition also in - the cavities of _Millepores_, and in the canals in the shells - of _Balanus_. According to him, the glauconite grains formed in - _Foraminifera_ lose after a time their calcareous envelopes, and - finally become 'conglomerated into small black pebbles,' sections - of which still show under a microscope the characteristic spiral - arrangement of the cells.[AC] - -[Footnote Z: _Silliman's Journal_ [2], xxix., p. 284; xxxii., p. 286. -_Geology of Canada_, p. 577.] - -[Footnote AA: _Silliman's Journal_ [2], xxxiii., p. 277. _Geology of -Canada_, p. 487.] - -[Footnote AB: _Silliman's Journal_ [2], xxii., p. 280.] - -[Footnote AC: _Report of United States Coast-Survey_, 1858, p. 248.] - - "It appears probable from these observations that glauconite is - formed by chemical reactions in the ooze at the bottom of the sea, - where dissolved silica comes in contact with iron oxide rendered - soluble by organic matter; the resulting silicate deposits itself in - the cavities of shells and other vacant spaces. A process analogous - to this in its results, has filled the chambers and canals of the - Laurentian _Foraminifera_ with other silicates; from the comparative - rarity of mechanical impurities in these silicates, however, it would - appear that they were deposited in clear water. Alumina and oxide of - iron enter into the composition of loganite as well as of glauconite; - but in the other replacing minerals, pyroxene and serpentine, we - have only silicates of lime and magnesia, which were probably formed - by the direct action of alkaline silicates, either dissolved in - surface-waters, or in those of submarine springs, upon the calcareous - and magnesian salts of the sea-water." - - [As stated in the text, the canals of Eozoon are sometimes filled - with dolomite, or in part with serpentine and in part with dolomite.] - - -(B.) Silurian Limestones holding Fossils infiltrated with Hydrous -Silicate. - - Since my attention has been directed to this subject, many - illustrations have come under my notice of Silurian limestones in - which the pores of fossils are infiltrated with hydrous silicates - akin to glauconite and serpentine. A limestone of this kind, - collected by Mr. Robb, at Pole Hill, in New Brunswick, afforded not - only beautiful specimens of portions of Crinoids preserved in this - way, but a sufficient quantity of the material was collected for an - exact analysis, a note on which was published in the Proceedings of - the Royal Irish Academy, 1871. - - The limestone of Pole Hill is composed almost wholly of organic - fragments, cemented by crystalline carbonate of lime, and traversed - by slender veins of the same mineral. Among the fragments may be - recognised under the microscope portions of Trilobites, and of - brachiopod and gastropod shells, and numerous joints and plates - of Crinoids. The latter are remarkable for the manner in which - their reticulated structure, which is similar to that of modern - Crinoids, has been injected with a silicious substance, which is - seen distinctly in slices, and still more plainly in decalcified - specimens. This filling is precisely similar in appearance to the - serpentine filling the canals of Eozoon, the only apparent difference - being in the forms of the cells and tubes of the Crinoids, as - compared with those of the Laurentian fossil; the same silicious - substance also occupies the cavities of some of the small shells, - and occurs in mere amorphous pieces, apparently filling interstices. - From its mode of occurrence, I have not the slightest doubt that - it occupied the cavities of the crinoidal fragments while still - recent, and before they had been cemented together by the calcareous - paste. This silicious filling is therefore similar on the one hand - to that effected by the ancient serpentine of the Laurentian, and - on the other to that which results from the depositions of modern - glauconite. The analysis of Dr. Hunt, which I give below, fully - confirms these analogies. - - I may add that I have examined under the microscope portions of the - substance prepared by Dr. Hunt for analysis, and find it to retain - its form, showing that it is the actual filling of the cavities. I - have also examined the small amount of insoluble silica remaining - after his treatment with acid and alkaline solvents, and find it to - consist of angular and rounded grains of quartzose sand. - - The following are Dr. Hunt's notes:-- - - "The fossiliferous limestone from Pole Hill, New Brunswick, probably - of Upper Silurian age, is light gray and coarsely granular. When - treated with dilute hydrochloric acid, it leaves a residue of 5·9 per - cent., and the solution gives 1·8 per cent. of alumina and oxide of - iron, and magnesia equal to 1·35 of carbonate--the remainder being - carbonate of lime. The insoluble matter separated by dilute acid, - after washing by decantation from a small amount of fine flocculent - matter, consists, apart from an admixture of quartz grains, entirely - of casts and moulded forms of a peculiar silicate, which Dr. Dawson - has observed in decalcified specimens filling the pores of crinoidal - stems; and which when separated by an acid, resembles closely under - the microscope the coralloidal forms of arragonite known as _flos - ferri_, the surfaces being somewhat rugose and glistening with - crystalline faces. This silicate is sub-translucent, and of a pale - green colour, but immediately becomes of a light reddish brown when - heated to redness in the air, and gives off water when heated in a - tube, without however, changing its form. It is partially decomposed - by strong hydrochloric acid, yielding a considerable amount of - protosalt of iron. Strong hot sulphuric acid readily and completely - decomposes it, showing it to be a silicate of alumina and ferrous - oxide, with some magnesia and alkalies, but with no trace of lime. - The separated silica, which remains after the action of the acid, - is readily dissolved by a dilute solution of soda, leaving behind - nothing but angular and partially rounded grains of sand, chiefly - of colourless vitreous quartz. An analysis effected in the way just - described on 1·187 grammes gave the following results, which give, by - calculation, the centesimal composition of the mineral:-- - - Silica ·3290 38·93 = 20·77 oxygen· - Alumina ·2440 28·88 = 13·46 " - Protoxyd of iron ·1593 18·86} - Magnesia ·0360 4·25} = 6·29 " - Potash ·0140 1·69} - Soda ·0042 ·48} - Water ·0584 6·91 = 6·14 " - Insoluble, quartz ·3420 - ------ ------ - 1·1869 100·00 - - "A previous analysis of a portion of the mixture by fusion with - carbonate of soda gave, by calculation, 18·80 p. c. of protoxide of - iron, and amounts of alumina and combined silica closely agreeing - with those just given. - - "The oxygen ratios, as above calculated, are nearly as 3 : 2 : 1 : 1. - This mineral approaches in composition to the jollyte of Von Kobell, - from which it differs in containing a portion of alkalies, and only - one half as much water. In these respects it agrees nearly with the - silicate found by Robert Hoffman, at Raspenau, in Bohemia, where it - occurs in thin layers alternating with picrosmine, and surrounding - masses of Eozoon in the Laurentian limestones of that region;[AD] - the Eozoon itself being there injected with a hydrous silicate which - may be described as intermediate between glauconite and chlorite in - composition. The mineral first mentioned is compared by Hoffman to - fahlunite, to which jollyte is also related in physical characters as - well as in composition. Under the names of fahlunite, gigantolite, - pinite, etc., are included a great class of hydrous silicates, which - from their imperfectly crystalline condition, have generally been - regarded, like serpentine, as results of the alteration of other - silicates. It is, however, difficult to admit that the silicate - found in the condition described by Hoffman, and still more the - present mineral, which injects the pores of palæozoic Crinoids, can - be any other than an original deposition, allied in the mode of its - formation, to the serpentine, pyroxene, and other minerals which have - injected the Laurentian Eozoon, and the serpentine and glauconite, - which in a similar manner fill Tertiary and recent shells." - -[Footnote AD: _Journ. für Prakt. Chemie_, Bd. 106 (Erster Jahrgang, -1869), p. 356.] - - -(C.) Various Minerals filling Cavities of Fossils in the Laurentian. - - The following on this subject is from a memoir by Dr. Hunt in the - _Twenty-first Report of the Regents of the University of New York_, - 1874:-- - - "Recent investigations have shown that in some cases the - dissemination of certain of these minerals through the crystalline - limestones is connected with organic forms. The observations - of Dr. Dawson and myself on the Eozoon Canadense showed that - certain silicates, namely serpentine, pyroxene, and loganite, - had been deposited in the cells and chambers left vacant by the - disappearance of the animal matter from the calcareous skeleton of - the foraminiferous organism; so that when this calcareous portion is - removed by an acid there remains a coherent mass, which is a cast of - the soft parts of the animal, in which, not only the chambers and - connecting canals, but the minute tubuli and pores are represented - by solid mineral silicates. It was shown that this process must have - taken place immediately after the death of the animal, and must have - depended on the deposition of these silicates from the waters of the - ocean. - - "The train of investigation thus opened up, has been pursued by - Dr. Gümbel, Director of the Geological Survey of Bavaria, who, in - a recent remarkable memoir presented to the Royal Society of that - country, has detailed his results. - - "Having first detected a fossil identical with the Canadian Eozoon - (together with several other curious microscopic organic forms not - yet observed in Canada), replaced by serpentine in a crystalline - limestone from the primitive group of Bavaria, which he identified - with the Laurentian system of this country, he next discovered a - related organism, to which he has given the name of Eozoon Bavaricum. - This occurs in a crystalline limestone belonging to a series of rocks - more recent than the Laurentian, but older than the Primordial zone - of the Lower Silurian, and designated by him the Hercynian clay slate - series, which he conceives may represent the Cambrian system of Great - Britain, and perhaps correspond to the Huronian series of Canada and - the United States. The cast of the soft parts of this new fossil is, - according to Gümbel, in part of serpentine, and in part of hornblende. - - "His attention was next directed to the green hornblende (pargasite) - which occurs in the crystalline limestone of Pargas in Finland, and - remains when the carbonate of lime is dissolved as a coherent mass - closely resembling that left by the irregular and acervuline forms - of Eozoon. The calcite walls also sometimes show casts of tubuli.... - A white mineral, probably scapolite was found to constitute some - tubercles associated with the pargasite, and the two mineral species - were in some cases united in the same rounded grain. - - "Similar observations were made by him upon specimens of coccolite - or green pyroxene, occurring in rounded and wrinkled grains in a - Laurentian limestone from New York. These, according to Gümbel, - present the same connecting cylinders and branching stems as the - pargasite, and are by him supposed to have been moulded in the - same manner.... Very beautiful evidences of the same organic - structure consisting of the casts of tubuli and their ramifications, - were also observed by Gümbel in a purely crystalline limestone, - enclosing granules of chondrodite, hornblende, and garnet, from - Boden in Saxony. Other specimens of limestone, both with and without - serpentine and chondrodite, were examined without exhibiting any - traces of these peculiar forms; and these negative results are - justly deemed by Gümbel as going to prove that the structure of - the others is really, like that of Eozoon, the result of the - intervention of organic forms. Besides the minerals observed in the - replacing substance of Eozoon in Canada, viz., serpentine, pyroxene, - and loganite, Gümbel adds chondrodite, hornblende, scapolite, and - probably also pyrallolite, quartz, iolite, and dichroite." - - -(D.) Glauconites. - - The following is from a paper by Dr. Hunt in the _Report of the - Survey of Canada_ for 1866:-- - - "In connection with the Eozoon it is interesting to examine more - carefully into the nature of the matters which have been called - glauconite or green-sand. These names have been given to substances - of unlike composition, which, however, occur under similar - conditions, and appear to be chemical deposits from water, filling - cavities in minute fossils, or forming grains in sedimentary rocks - of various ages. Although greenish in colour, and soft and earthy - in texture, it will be seen that the various glauconites differ - widely in composition. The variety best known, and commonly regarded - as the type of the glauconites, is that found in the green-sand of - Cretaceous age in New Jersey, and in the Tertiary of Alabama; the - glauconite from the Lower Silurian rocks of the Upper Mississippi is - identical with it in composition. Analysis shows these glauconites to - be essentially hydrous silicates of protoxyd of iron, with more or - less alumina, and small but variable quantities of magnesia, besides - a notable amount of potash. This alkali is, however, sometimes - wanting, as appears from the analysis of a green-sand from Kent in - England, by that careful chemist, the late Dr. Edward Turner, and - in another examined by Berthier, from the _calcaire grossier_, near - Paris, which is essentially a serpentine in composition, being a - hydrous silicate of magnesia and protoxyd of iron. A comparison of - these last two will show that the loganite, which fills the ancient - Foraminifer of Burgess, is a silicate nearly related in composition. - - I. Green-sand from the _calcaire grossier_, near Paris. Berthier - (cited by Beudant, _Mineralogie_, ii., 178). - - II. Green-sand from Kent, England. Dr. Edward Turner (cited by - Rogers, Final Report, Geol. N. Jersey, page 206). - - III. Loganite from the Eozoon of Burgess. - - IV. Green-sand, Lower Silurian; Red Bird, Minnesota. - - V. Green-sand, Cretaceous, New Jersey. - - VI. Green-sand, Lower Silurian, Orleans Island. - - The last four analyses are by myself. - - I. II. III. IV. V. VI. - - Silica 40·0 48·5 35·14 46·58 50·70 50·7 - - Protoxyd of iron 24·7 22·0 8·60 20·61 22·50 8·6 - - Magnesia 16·6 3·8 31·47 1·27 2·16 3·7 - - Lime 3·3 .... .... 2·49 1·11 .... - - Alumina 1·7 17·0 10·15 11·45 8·03 19·8 - - Potash .... traces. .... 6·96 5·80 8·2 - - Soda .... .... .... ·98 ·75 ·5 - - Water 12·6 7·0 14·64 9·66 8·95 8·5 - ---- ---- ------ ------ ------ ----- - 98·9 98·3 100·00 100·00 100·00 100·0" - -[Illustration: - Plate VI. - - From a Photo. by Weston. Vincent Brooks, Day & Son Lith. - - CANAL SYSTEM OF EOZOON. - - SLICES OF THE FOSSIL (MAGNIFIED.) - - _To face Chap. 6._] - - - - -CHAPTER VI. - -CONTEMPORARIES AND SUCCESSORS OF EOZOON. - - -The name Eozoon, or Dawn-animal, raises the question whether we shall -ever know any earlier representative of animal life. Here I think -it necessary to explain that in suggesting the name Eozoon for the -earliest fossil, and Eozoic for the formation in which it is contained, -I had no intention to affirm that there may not have been precursors -of the Dawn-animal. By the similar term, Eocene, Lyell did not mean -to affirm that there may not have been modern types in the preceding -geological periods: and so the dawn of animal life may have had its -gray or rosy breaking at a time long anterior to that in which Eozoon -built its marble reefs. When the fossils of this early auroral time -shall be found, it will not be hard to invent appropriate names for -them. There are, however, two reasons that give propriety to the -name in the present state of our knowledge. One is, that the Lower -Laurentian rocks are absolutely the oldest that have yet come under -the notice of geologists, and at the present moment it seems extremely -improbable that any older sediments exist, at least in a condition to -be recognised as such. The other is that Eozoon, as a member of the -group Protozoa, of gigantic size and comprehensive type, and oceanic in -its habitat, is as likely as any other creature that can be imagined -to have been the first representative of animal life on our planet. -Vegetable life may have preceded it, nay probably did so by at least -one great creative æon, and may have accumulated previous stores of -organic matter; but if any older forms of animal life existed, it is -certain at least that they cannot have belonged to much simpler or more -comprehensive types. It is also to be observed that such forms of life, -if they did exist, may have been naked protozoa, which may have left no -sign of their existence except a minute trace of carbonaceous matter, -and perhaps not even this. - -But if we do not know, and perhaps we are not likely to know, any -animals older than Eozoon, may we not find traces of some of its -contemporaries, either in the Eozoon limestones themselves, or other -rocks associated with them? Here we must admit that a deep sea -Foraminiferal limestone may give a very imperfect indication of the -fauna of its time. A dredger who should have no other information as -to the existing population of the world, except what he could gather -from the deposits formed under several hundred fathoms of water, would -necessarily have very inadequate conceptions of the matter. In like -manner a geologist who should have no other information as to the -animal life of the Mesozoic ages than that furnished by some of the -thick beds of white chalk might imagine that he had reached a period -when the simplest kinds of protozoa predominated over all other -forms of life; but this impression would at once be corrected by the -examination of other deposits of the same age: so our inferences as to -the life of the Laurentian from the contents of its oceanic limestones -may be very imperfect, and it may yet yield other and various fossils. -Its possibilities are, however, limited by the fact that before we -reach this great depth in the earth's crust, we have already left -behind in much newer formations all traces of animal life except a -few of the lower forms of aquatic invertebrates; so that we are not -surprised to find only a limited number of living things, and those of -very low type. Do we then know in the Laurentian even a few distinct -species, or is our view limited altogether to Eozoon Canadense? In -answering this question we must bear in mind that the Laurentian itself -was of vast duration, and that important changes of life may have taken -place even between the deposition of the Eozoon limestones and that -of those rocks in which we find the comparatively rich fauna of the -Primordial age. This subject was discussed by the writer as early as -1865, and I may repeat here what could be said in relation to it at -that time:-- - -"In connection with these remarkable remains, it appeared desirable to -ascertain, if possible, what share these or other organic structures -may have had in the accumulation of the limestones of the Laurentian -series. Specimens were therefore selected by Sir W. E. Logan, and -slices were prepared under his direction. On microscopic examination, -a number of these were found to exhibit merely a granular aggregation -of crystals, occasionally with particles of graphite and other foreign -minerals, or a laminated mixture of calcareous and other matters, in -the manner of some more modern sedimentary limestones. Others, however, -were evidently made up almost entirely of fragments of Eozoon, or of -mixtures of these with other calcareous and carbonaceous fragments -which afford more or less evidence of organic origin. The contents of -these organic limestones may be considered under the following heads:-- - -1. Remains of Eozoon. - -2. Other calcareous bodies, probably organic. - -3. Objects imbedded in the serpentine. - -4. Carbonaceous matters. - -5. Perforations, or worm-burrows. - -"1. The more perfect specimens of Eozoon do not constitute the mass -of any of the larger specimens in the collection of the Survey; but -considerable portions of some of them are made up of material of -similar minute structure, destitute of lamination, and irregularly -arranged. Some of this material gives the impression that there may -have been organisms similar to Eozoon, but growing in an irregular -or acervuline manner without lamination. Of this, however, I cannot -be certain; and on the other hand there is distinct evidence of the -aggregation of fragments of Eozoon in some of these specimens. In -some they constitute the greater part of the mass. In others they -are embedded in calcareous matter of a different character, or in -serpentine or granular pyroxene. In most of the specimens the cells of -the fossils are more or less filled with these minerals; and in some -instances it would appear that the calcareous matter of fragments of -Eozoon has been in part replaced by serpentine." - -"2. Intermixed with the fragments of Eozoon above referred to, are -other calcareous matters apparently fragmentary. They are of various -angular and rounded forms, and present several kinds of structure. The -most frequent of these is a strong lamination varying in direction -according to the position of the fragments, but corresponding, as -far as can be ascertained, with the diagonal of the rhombohedral -cleavage. This structure, though crystalline, is highly characteristic -of crinoidal remains when preserved in altered limestones. The more -dense parts of Eozoon, destitute of tubuli, also sometimes show this -structure, though less distinctly. Other fragments are compact and -structureless, or show only a fine granular appearance; and these -sometimes include grains, patches, or fibres of graphite. In Silurian -limestones, fragments of corals and shells which have been partially -infiltrated with bituminous matter, show a structure like this. On -comparison with altered organic limestones of the Silurian system, -these appearances would indicate that in addition to the debris of -Eozoon, other calcareous structures, more like those of crinoids, -corals, and shells, have contributed to the formation of the -Laurentian limestones. - -"3. In the serpentine[AE] filling the chambers of a large specimen of -Eozoon from Burgess, there are numerous small pieces of foreign matter; -and the silicate itself is laminated, indicating its sedimentary -nature. Some of the included fragments appear to be carbonaceous, -others calcareous; but no distinct organic structure can be detected -in them. There are, however, in the serpentine, many minute silicious -grains of a bright green colour, resembling green-sand concretions; -and the manner in which these are occasionally arranged in lines and -groups, suggests the supposition that they may possibly be casts of -the interior of minute Foraminiferal shells. They may, however, be -concretionary in their origin. - -[Footnote AE: This is the dark green mineral named loganite by Dr. -Hunt.] - -"4. In some of the Laurentian limestones submitted to me by Sir W. -E. Logan, and in others which I collected some years ago at Madoc, -Canada West, there are fibres and granules of carbonaceous matter, -which do not conform to the crystalline structure, and present forms -quite similar to those which in more modern limestones result from -the decomposition of algæ. Though retaining mere traces of organic -structure, no doubt would be entertained as to their vegetable origin -if they were found in fossiliferous limestones. - -"5. A specimen of impure limestone from Madoc, in the collection of -the Canadian Geological Survey, which seems from its structure to -have been a finely laminated sediment, shows perforations of various -sizes, somewhat scalloped at the sides, and filled with grains of -rounded silicious sand. In my own collection there are specimens -of micaceous slate from the same region, with indications on their -weathered surfaces of similar rounded perforations, having the aspect -of Scolithus, or of worm-burrows. - -"Though the abundance and wide distribution of Eozoon, and the -important part it seems to have acted in the accumulation of limestone, -indicate that it was one of the most prevalent forms of animal -existence in the seas of the Laurentian period, the non-existence of -other organic beings is not implied. On the contrary, independently of -the indications afforded by the limestones themselves, it is evident -that in order to the existence and growth of these large Rhizopods, the -waters must have swarmed with more minute animal or vegetable organisms -on which they could subsist. On the other hand, though this is a less -certain inference, the dense calcareous skeleton of Eozoon may indicate -that it also was liable to the attacks of animal enemies. It is also -possible that the growth of Eozoon, or the deposition of the serpentine -and pyroxene in which its remains have been preserved, or both, may -have been connected with certain oceanic depths and conditions, and -that we have as yet revealed to us the life of only certain stations -in the Laurentian seas. Whatever conjectures we may form on these more -problematic points, the observations above detailed appear to establish -the following conclusions:-- - -"First, that in the Laurentian period, as in subsequent geological -epochs, the Rhizopods were important agents in the accumulation of -beds of limestone; and secondly, that in this early period these low -forms of animal life attained to a development, in point of magnitude -and complexity, unexampled, in so far as yet known, in the succeeding -ages of the earth's history. This early culmination of the Rhizopods is -in accordance with one of the great laws of the succession of living -beings, ascertained from the study of the introduction and progress of -other groups; and, should it prove that these great Protozoans were -really the dominant type of animals in the Laurentian period, this fact -might be regarded as an indication that in these ancient rocks we may -actually have the records of the first appearance of animal life on our -planet." - -With reference to the first of the above heads, I have now to state -that it seems quite certain that the upper and younger portions of -the masses of Eozoon often passed into the acervuline form, and the -period in which this change took place seems to have depended on -circumstances. In some specimens there are only a few regular layers, -and then a heap of irregular cells. In other cases a hundred or more -regular layers were formed; but even in this case little groups of -irregular cells occurred at certain points near the surface. This -may be seen in plate III. I have also found some masses clearly not -fragmental which consist altogether of acervuline cells. A specimen -of this kind is represented in fig. 31. It is oval in outline, about -three inches in length, wholly made up of rounded or cylindrical -cells, the walls of which have a beautiful tubular structure, but -there is little or no supplemental skeleton. Whether this is a portion -accidentally broken off from the top of a mass of Eozoon, or a -peculiar varietal form, or a distinct species, it would be difficult -to determine. In the meantime I have described it as a variety, -"_acervulina_," of the species Eozoon Canadense.[AF] Another variety -also, from Petite Nation, shows extremely thin laminæ, closely placed -together and very massive, and with little supplemental skeleton. This -may be allied to the last, and may be named variety "_minor_." - -[Footnote AF: _Proceedings of Geological Society_, 1875.] - -[Illustration: Fig. 31. _Acervuline Variety of Eozoon, St. Pierre._ - -(_a._) General form, half natural size. (_b._) Portion of cellular -interior, magnified, showing the course of the tubuli.] - -All this, however, has nothing to do with the layers of fragments of -Eozoon which are scattered through the Laurentian limestones. In these -the fossil is sometimes preserved in the ordinary manner, with its -cavities filled with serpentine, and the thicker parts of the skeleton -having their canals filled with this substance. In this case the -chambers may have been occupied with serpentine before it was broken -up. At St. Pierre there are distinct layers of this kind, from half an -inch to several inches in thickness, regularly interstratified with -the ordinary limestone. In other layers no serpentine occurs, but the -interstices of the fragments are filled with crystalline dolomite or -magnesian limestone, which has also penetrated the canals; and there -are indications, though less manifest, that some at least of the layers -of pure limestone are composed of fragmental Eozoon. In the Laurentian -limestone of Wentworth, belonging apparently to the same band with -that of St. Pierre, there are many small rounded pieces of limestone, -evidently the debris of some older rock, broken up and rounded by -attrition. In some of these fragments the structure of Eozoon may be -plainly perceived. This shows that still older limestones composed of -Eozoon were at that time undergoing waste, and carries our view of the -existence of this fossil back to the very beginning of the Laurentian. - -With respect to organic fragments not showing the structure of Eozoon, -I have not as yet been able to refer these to any definite origin. Some -of them may be simply thick portions of the shell of Eozoon with their -pores filled with calcite, so as to present a homogeneous appearance. -Others have much the appearance of fragments of such Primordial forms -as _Archæocyathus_, to be described in the sequel; but after much -careful search, I have thus far been unable to say more than I could -say in 1865. - -[Illustration: Fig. 32. _Archæospherinæ from St. Pierre._ - -(_a._) Specimens dissolved out by acid. The lower one showing interior -septa. (_b._) Specimens seen in section.] - -[Illustration: Fig. 33. _Archæospherinæ from Burgess Eozoon._ - -Magnified.] - -[Illustration: Fig. 34. _Archæospherinæ from Wentworth Limestone._ - -Magnified.] - -It is different, however, with the round cells infiltrated with -serpentine and with the silicious grains included in the loganite. I -have already referred to and figured (fig. 18) the remarkable rounded -bodies occurring at Long Lake. I now figure similar bodies found mixed -with fragmental Eozoon and in separate thin layers at St. Pierre (fig. -32), also some of the singular grains found in the loganite occupying -the chambers of Eozoon from Burgess (fig. 33), and a beaded body set -free by acid, with others of irregular forms, from the limestone of -Wentworth (fig. 34). All these I think are essentially of the same -nature, namely, chambers originally invested with a tubulated wall -like Eozoon, and aggregated in groups, sometimes in a linear manner, -sometimes spirally, like those Globigerinæ which constitute the mass -of modern deep-sea dredgings and also of the chalk. These bodies occur -dispersed in the limestone, arranged in thin layers parallel to the -bedding or sometimes in the large chamber-cavities of Eozoon. They -are so variable in size and form that it is not unlikely they may be -of different origins. The most probable of these may be thus stated. -First, they may in some cases be the looser superficial parts of the -surface of Eozoon broken up into little groups of cells. Secondly, -they may be few-celled germs or buds given off from Eozoon. Thirdly, -they may be smaller Foraminifera, structurally allied to Eozoon, but -in habit of growth resembling those little globe-shaped forms which, -as already stated, abound in chalk and in the modern ocean. The latter -view I should regard as highly probable in the case of many of them; -and I have proposed for them, in consequence, and as a convenient name, -_Archæospherinæ_, or ancient spherical animals. - -Carbonaceous matter is rare in the true Eozoon limestones, and, as -already stated, I would refer the Laurentian graphite or plumbago -mainly to plants. With regard to the worm-burrows referred to in 1865, -there can be no doubt of their nature, but there is some doubt as to -whether the beds that contain them are really Lower Laurentian. They -may be Upper Laurentian or Huronian. I give here figures of these -burrows as published in 1866[AG] (fig. 35). The rocks which contain -them hold also fragments of Eozoon, and are not known to contain other -fossils. - -[Footnote AG: _Journal of Geological Society._] - -[Illustration: Fig. 35. _Annelid Burrows, Laurentian or Huronian._ - -Fig 1. _Transverse section of Worm-burrow_--magnified, as a transparent -object. (_a._) Calcareo-silicious rock. (_b._) Space filled with -calcareous spar. (_c._) Sand agglutinated and stained black. (_d._) -Sand less agglutinated and uncoloured. Fig. 2. _Transverse section of -Worm-burrow on weathered surface_, natural size. Fig. 3. _The same_, -magnified.] - -If we now turn to other countries in search of contemporaries of -Eozoon, I may refer first to some specimens found by my friend Dr. -Honeyman at Arisaig, in Nova Scotia, in beds underlying the Silurian -rocks of that locality, but otherwise of uncertain age. I do not vouch -for them as Laurentian, and if of that age they seem to indicate a -species distinct from that of Canada proper. They differ in coarser -tubulation, and in their canals being large and beaded, and less -divergent. I proposed for these specimens, in some notes contributed to -the survey of Canada, the name _Eozoon Acadianum_. - -Dr. Gümbel, the Director of the Geological Survey of Bavaria, is -one of the most active and widely informed of European geologists, -combining European knowledge with an extensive acquaintance with the -larger and in some respects more typical areas of the older rocks in -America, and stratigraphical geology with enthusiastic interest in the -microscopic structures of fossils. He at once and in a most able manner -took up the question of the application of the discoveries in Canada -to the rocks of Bavaria. The spirit in which he did so may be inferred -from the following extract:-- - -"The discovery of organic remains in the crystalline limestones of the -ancient gneiss of Canada, for which we are indebted to the researches -of Sir William Logan and his colleagues, and to the careful microscopic -investigations of Drs. Dawson and Carpenter, must be regarded as -opening a new era in geological science. - -"This discovery overturns at once the notions hitherto commonly -entertained with regard to the origin of the stratified primary -limestones, and their accompanying gneissic and quartzose strata, -included under the general name of primitive crystalline schists. It -shows us that these crystalline stratified rocks, of the so-called -primary system, are only a backward prolongation of the chain of -fossiliferous strata; the elements of which were deposited as oceanic -sediment, like the clay-slates, limestones, and sandstones of the -palæozoic formations, and under similar conditions, though at a time -far more remote, and more favourable to the generation of crystalline -mineral compounds. - -"In this discovery of organic remains in the primary rocks, we hail -with joy the dawn of a new epoch in the critical history of these -earlier formations. Already in its light, the primeval geological time -is seen to be everywhere animated, and peopled with new animal forms -of whose very existence we had previously no suspicion. Life, which -had hitherto been supposed to have first appeared in the Primordial -division of the Silurian period, is now seen to be immeasurably -lengthened beyond its former limit, and to embrace in its domain the -most ancient known portions of the earth's crust. It would almost -seem as if organic life had been awakened simultaneously with the -solidification of the earth's crust. - -"The great importance of this discovery cannot be clearly understood, -unless we first consider the various and conflicting opinions -and theories which had hitherto been maintained concerning the -origin of these primary rocks. Thus some, who consider them as the -first-formed crust of a previously molten globe, regard their apparent -stratification as a kind of concentric parallel structure, developed -in the progressive cooling of the mass from without. Others, while -admitting a similar origin of these rocks, suppose their division -into parallel layers to be due, like the lamination of clay-slates, -to lateral pressure. If we admit such views, the igneous origin of -schistose rocks becomes conceivable, and is in fact maintained by many. - -"On the other hand, we have the school which, while recognising the -sedimentary origin of these crystalline schists, supposes them to -have been metamorphosed at a later period; either by the internal -heat, acting in the deeply buried strata; by the proximity of eruptive -rocks; or finally, through the agency of permeating waters charged with -certain mineral salts. - -"A few geologists only have hitherto inclined to the opinion that -these crystalline schists, while possessing real stratification, -and sedimentary in their origin, were formed at a period when the -conditions were more favourable to the production of crystalline -materials than at present. According to this view, the crystalline -structure of these rocks is an original condition, and not one -superinduced at a later period by metamorphosis. In order, however, -to arrange and classify these ancient crystalline rocks, it becomes -necessary to establish by superposition, or by other evidence, -differences in age, such as are recognised in the more recent -stratified deposits. The discovery of similar organic remains, -occupying a determinate position in the stratification, in different -and remote portions of these primitive rocks, furnishes a powerful -argument in favour of the latter view, as opposed to the notion which -maintains the metamorphic origin of the various minerals and rocks of -these ancient formations; so that we may regard the direct formation of -these mineral elements, at least so far as these fossiliferous primary -limestones are concerned, as an established fact." - -His first discovery is thus recorded, in terms which show the very -close resemblance of the Bavarian and Canadian Eozoic. - -"My discovery of similar organic remains in the serpentine-limestone -from near Passau was made in 1865, when I had returned from my -geological labours of the summer, and received the recently published -descriptions of Messrs. Logan, Dawson, etc. Small portions of this -rock, gathered in the progress of the Geological Survey in 1854, -and ever since preserved in my collection, having been submitted -to microscopic examination, confirmed in the most brilliant manner -the acute judgment of the Canadian geologists, and furnished -palæontological evidence that, notwithstanding the great distance which -separates Canada from Bavaria, the equivalent primitive rocks of the -two regions are characterized by similar organic remains; showing at -the same time that the law governing the definite succession of organic -life on the earth is maintained even in these most ancient formations. -The fragments of serpentine-limestone, or ophicalcite, in which I first -detected the existence of Eozoon, were like those described in Canada, -in which the lamellar structure is wanting, and offer only what Dr. -Carpenter has called an acervuline structure. For further confirmation -of my observations, I deemed it advisable, through the kindness of -Sir Charles Lyell, to submit specimens of the Bavarian rock to the -examination of that eminent authority, Dr. Carpenter, who, without any -hesitation, declared them to contain Eozoon. - -"This fact being established, I procured from the quarries near Passau -as many specimens of the limestone as the advanced season of the year -would permit; and, aided by my diligent and skillful assistants, -Messrs. Reber and Schwager, examined them by the methods indicated by -Messrs. Dawson and Carpenter. In this way I soon convinced myself of -the general similarity of our organic remains with those of Canada. -Our examinations were made on polished sections and in portions etched -with dilute nitric acid, or, better, with warm acetic acid. The most -beautiful results were however obtained by etching moderately thin -sections, so that the specimens may be examined at will either by -reflected or transmitted light. - -"The specimens in which I first detected Eozoon came from a quarry -at Steinhag, near Obernzell, on the Danube, not far from Passau. The -crystalline limestone here forms a mass from fifty to seventy feet -thick, divided into several beds, included in the gneiss, whose general -strike in this region is N.W., with a dip of 40°-60° N.E. The limestone -strata of Steinhag have a dip of 45° N.E. The gneiss of this vicinity -is chiefly grey, and very silicious, containing dichroite, and of -the variety known as dichroite-gneiss; and I conceive it to belong, -like the gneiss of Bodenmais and Arber, to that younger division of -the primitive gneiss system which I have designated as the Hercynian -gneiss formation; which, both to the north, between Tischenreuth and -Mahring, and to the south on the north-west of the mountains of Ossa, -is immediately overlaid by the mica-slate formation. Lithologically, -this newer division of the gneiss is characterized by the predominance -of a grey variety, rich in quartz, with black magnesian-mica and -orthoclase, besides which a small quantity of oligoclase is never -wanting. A further characteristic of this Hercynian gneiss is the -frequent intercalation of beds of rocks rich in hornblende, such as -hornblende-schist, amphibolite, diorite, syenite, and syenitic granite, -and also of serpentine and granulite. Beds of granular limestone, -or of calcareous schists are also never altogether wanting; while -iron pyrites and graphite, in lenticular masses, or in local beds -conformable to the great mass of the gneiss strata, are very generally -present. - -"In the large quarry of Steinhag, from which I first obtained the -Eozoon, the enclosing rock is a grey hornblendic gneiss, which -sometimes passes into a hornblende-slate. The limestone is in many -places overlaid by a bed of hornblende-schist, sometimes five feet -in thickness, which separates it from the normal gneiss. In many -localities, a bed of serpentine, three or four feet thick, is -interposed between the limestone and the hornblende-schist; and in -some cases a zone, consisting chiefly of scapolite, crystalline and -almost compact, with an admixture however of hornblende and chlorite. -Below the serpentine band, the crystalline limestone appears divided -into distinct beds, and encloses various accidental minerals, among -which are reddish-white mica, chlorite, hornblende, tremolite, -chondrodite, rosellan, garnet, and scapolite, arranged in bands. -In several places the lime is mingled with serpentine, grains or -portions of which, often of the size of peas, are scattered through -the limestone with apparent irregularity, giving rise to a beautiful -variety of ophicalcite or serpentine-marble. These portions, which are -enclosed in the limestone destitute of serpentine, always present a -rounded outline. In one instance there appears, in a high naked wall -of limestone without serpentine, the outline of a mass of ophicalcite, -about sixteen feet long and twenty-five feet high, which, rising from -a broad base, ends in a point, and is separated from the enclosing -limestone by an undulating but clearly defined margin, as already well -described by Wineberger. This mass of ophicalcite recalls vividly a -reef-like structure. Within this and similar masses of ophicalcite in -the crystalline limestone, there are, so far as my observations in 1854 -extend, no continuous lines or concentric layers of serpentine to be -observed, this mineral being always distributed in small grains and -patches. The few apparently regular layers which may be observed are -soon interrupted, and the whole aggregation is irregular." - -It will be observed that this acervuline Eozoon of Steinhag appears to -exist in large reefs, and that in its want of lamination it differs -from the Canadian examples. In fossils of low organization, like -Foraminifera, such differences are often accidental and compatible with -specific unity, but yet there may be a difference specifically in the -Bavarian Eozoon as compared with the Canadian. - -Gümbel also found in the Finnish and Bavarian limestones knotted -chambers, like those of Wentworth above mentioned (fig. 36), which he -regards as belonging to some other organism than Eozoon; and flocculi -having tubes, pores, and reticulations which would seem to point to the -presence of structures akin to sponges or possibly remains of seaweeds. -These observations Gümbel has extended into other localities in Bavaria -and Bohemia, and also in Silesia and Sweden, establishing the existence -of Eozoon fossils in all the Laurentian limestones of the middle and -north of Europe. - -[Illustration: Fig. 36. _Archæospherinæ from Pargas in Finland._ -(_After Gümbel._) - -Magnified.] - -Gümbel has further found in beds overlying the older Eozoic series, -and probably of the same age with the Canadian Huronian, a different -species of Eozoon, with smaller and more contracted chambers, and -still finer and more crowded canals. This, which is to be regarded as -a distinct species, or at least a well-marked varietal form, he has -named _Eozoon Bavaricum_ (fig. 37). Thus this early introduction of -life is not peculiar to that old continent which we sometimes call the -New World, but applies to Europe as well, and Europe has furnished a -successor to Eozoon in the later Eozoic or Huronian period. In rocks of -this age in America, after long search and much slicing of limestones, -I have hitherto failed to find any decided organic remains other than -the Tudor and Madoc specimens of Eozoon. If these are really Huronian -and not Laurentian, the Eozoon from this horizon does not sensibly -differ from that of the Lower Laurentian. The curious limpet-like -objects from Newfoundland, discovered by Murray, and described by -Billings,[AH] under the name _Aspidella_, are believed to be Huronian, -but they have no connection with Eozoon, and therefore need not detain -us here. - -[Footnote AH: _Canadian Naturalist_, 1871.] - -[Illustration: Fig. 37. _Section of Eozoon Bavaricum, with Serpentine, -from the Crystalline Limestone of the Hercynian primitive Clay-state -Formation at Hohenberg; 25 diameters._ - -(_a._) Sparry carbonate of lime. (_b._) Cellular carbonate of lime. -(_c._) System of tubuli. (_d._) Serpentine replacing the coarser -ordinary variety. (_e._) Serpentine and hornblende replacing the finer -variety, in the very much contorted portions.] - -Leaving the Eozoic age, we find ourselves next in the Primordial or -Cambrian, and here we discover the sea already tenanted by many -kinds of crustaceans and shell-fishes, which have been collected and -described by palæontologists in Bohemia, Scandinavia, Wales, and North -America;[AI] curiously enough, however, the rocks of this age are -not so rich in Foraminifera as those of some succeeding periods. Had -this primitive type played out its part in the Eozoic and exhausted -its energies, and did it remain in abeyance in the Primordial age to -resume its activity in the succeeding times? It is not necessary to -believe this. The geologist is familiar with the fact, that in one -formation he may have before him chiefly oceanic and deep-sea deposits, -and in another those of the shallower waters, and that alternations -of these may, in the same age or immediately succeeding ages, present -very different groups of fossils. Now the rocks and fossils of the -Laurentian seem to be oceanic in character, while the Huronian and -early Primordial rocks evidence great disturbances, and much coarse -and muddy sediment, such as that found in shallows or near the land. -They abound in coarse conglomerates, sandstones and thick beds of slate -or shale, but are not rich in limestones, which do not in the parts -of the world yet explored regain their importance till the succeeding -Siluro-Cambrian age. No doubt there were, in the Primordial, deep-sea -areas swarming with Foraminifera, the successors of Eozoon; but these -are as yet unknown or little known, and our known Primordial fauna is -chiefly that of the shallows. Enlarged knowledge may thus bridge over -much of the apparent gap in the life of these two great periods. - -[Footnote AI: Barrande, Angelin, Hicks, Hall, Billings, etc.] - -Only as yet on the coast of Labrador and neighbouring parts of North -America, and in rocks that were formed in seas that washed the old -Laurentian rocks, in which Eozoon was already as fully sealed up as -it is at this moment, do we find Protozoa which can claim any near -kinship to the proto-foraminifer. These are the fossils of the genus -_Archæocyathus_--"ancient cup-sponges, or cup-foraminifers," which -have been described in much detail by Mr. Billings in the reports of -the Canadian Survey. Mr. Billings regards them as possibly sponges, -or as intermediate between these and Foraminifera, and the silicious -spicules found in some of them justify this view, unless indeed, as -partly suspected by Mr. Billings, these belong to true sponges which -may have grown along with Archæocyathus or attached to it. Certain -it is, however, that if allied to sponges, they are allied also to -Foraminifera, and that some of them deviate altogether from the sponge -type and become calcareous chambered bodies, the animals of which can -have differed very little from those of the Laurentian Eozoon. It is -to these calcareous Foraminiferal species that I shall at present -restrict my attention. I give a few figures, for which I am indebted to -Mr. Billings, of three of his species (figs. 38 to 40), with enlarged -drawings of the structures of one of them which has the most decidedly -foraminiferal characters. - -[Illustration: Fig. 38. _Archæocyathus Minganensis--a Primordial -Protozoon._ (_After Billings._) - -(_a._) Pores of the inner wall.] - -[Illustration: Fig. 39. _Archæocyathus profundus--showing the base of -attachment and radiating chambers._ (_After Billings._)] - -[Illustration: Fig. 40. _Archæocyathus Atlanticus--showing outer -surface and longitudinal and transverse sections._ (_After Billings._)] - -[Illustration: Fig. 41. _Structures of Archæocyathus Profundus._ - -(_a._) Lower acervuline portion. (_b._) Upper portion, with three of -the radiating laminæ. (_c._) Portion of lamina with pores and thickened -part with canals. In figs. _a_ and _b_ the calcareous part is unshaded.] - -To understand Archæocyathus, let us imagine an inverted cone of -carbonate of lime from an inch or two to a foot in length, and with -its point buried in the mud at the bottom of the sea, while its open -cup extends upward into the water. The lower part buried in the soil -is composed of an irregular acervuline network of thick calcareous -plates, enclosing chambers communicating with one another (figs. 40 -and 41 A). Above this where the cup expands, its walls are composed -of thin outer and inner plates, perforated with innumerable holes, -and connected with each other by vertical plates, which are also -perforated with round pores, establishing a communication between the -radiating chambers into which they divide the thickness of the wall -(figs. 38, 39, and 41 B). In such a structure the chambers in the wall -of the cup and the irregular chambers of the base would be filled with -gelatinous animal matter, and the pseudopods would project from the -numerous pores in the inner and outer wall. In the older parts of the -skeleton, the structure is further complicated by the formation of -thin transverse plates, irregular in distribution, and where greater -strength is required a calcareous thickening is added, which in some -places shows a canal system like that of Eozoon (fig. 41, B, C).[AJ] -As compared with Eozoon, the fossils want its fine perforated wall, -but have a more regular plan of growth. There are fragments in the -Eozoon limestones which may have belonged to structures like these; -and when we know more of the deep sea of the Primordial, we may -recover true species of Eozoon from it, or may find forms intermediate -between it and Archæocyathus. In the meantime I know no nearer bond of -connection between Eozoon and the Primordial age than that furnished -by the ancient cup Zoophytes of Labrador, though I have searched very -carefully in the fossiliferous conglomerates of Cambrian age on the -Lower St. Lawrence, which contain rocks of all the formations from the -Laurentian upwards, often with characteristic fossils. I have also made -sections of many of the fossiliferous pebbles in these conglomerates -without finding any certain remains of such organisms, though the -fragments of the crusts of some of the Primordial tribolites, when -their tubuli are infiltrated with dark carbonaceous matter, are so like -the supplemental skeleton of Eozoon, that but for their forms they -might readily be mistaken for it; and associated with them are broken -pieces of other porous organisms which may belong to Protozoa, though -this is not yet certain. - -[Footnote AJ: On the whole these curious fossils, if regarded as -Foraminifera, are most nearly allied to the Orbitolites and Dactyloporæ -of the Early Tertiary period, as described by Carpenter.] - -Of all the fossils of the Silurian rocks those which most resemble -Eozoon are the _Stromatoporæ_, or "layer-corals," whose resemblance -to the old Laurentian fossil at once struck Sir William Logan; and -these occur in the earliest great oceanic limestones which succeed the -Primordial period, those of the Trenton group, in the Siluro-Cambrian. -From this they extend upward as far as the Devonian, appearing -everywhere in the limestones, and themselves often constituting large -masses of calcareous rock. Our figure (fig. 42) shows a small example -of one of these fossils; and when sawn asunder or broken across and -weathered, they precisely resemble Eozoon in general appearance, -especially when, as sometimes happens, their cell-walls have been -silicified. - -[Illustration: Fig. 42. _Stromatopora rugosa, Hall--Lower Silurian, -Canada._ (_After Billings._) - -The specimen is of smaller size than usual, and is silicified. It is -probably inverted in position, and the concentric marks on the outer -surface are due to concretions of silica.] - -There are, however, different types of these fossils. The most common, -the Stromatoporæ properly so called, consist of concentric layers of -calcareous matter attached to each other by pillar-like processes, -which, as well as the layers, are made up of little threads of -limestone netted together, or radiating from the tops and bottoms of -the pillars, and forming a very porous substance. Though they have -been regarded as corals by some, they are more generally believed -to be Protozoa; but whether more nearly allied to sponges or to -Foraminifera may admit of doubt. Some of the more porous kinds are -not very dissimilar from calcareous sponges, but they generally want -true oscula and pores, and seem better adapted to shield the gelatinous -body of a Foraminifer projecting pseudopods in search of food, than -that of a sponge, living by the introduction of currents of water. Many -of the denser kinds, however, have their calcareous floors so solid -that they must be regarded as much more nearly akin to Foraminifers, -and some of them have the same irregular inosculation of these floors -observed in Eozoon. Figs. 43, A to D, show portions of species of -this description, in which the resemblance to Eozoon in structure and -arrangement of parts is not remote. - -[Illustration: Fig. 43. _Structures of Stromatopora._ - -(_a._) Portion of an oblique section magnified, showing laminæ and -columns. (_b._) Portion of wall with pores, and crusted on both sides -with quartz crystals. (_c._) Thickened portion of wall with canals. -(_d._) Portion of another specimen, showing irregular laminæ and -pillars.] - -These fossils, however, show no very distinct canal system or -supplemental skeleton, but this also appears in those forms which have -been called Caunopora or Cœnostroma. In these the plates are traversed -by tubes, or groups of tubes, which in each successive floor give out -radiating and branching canals exactly like those of Eozoon, though -more regularly arranged; and if we had specimens with the canals -infiltrated with glauconite or serpentine, the resemblance would be -perfect. When, as in figs. 44 and 45 A, these canals are seen on the -abraded surface, they appear as little grooves arranged in stars, -which resemble the radiating plates of corals, but this resemblance -is altogether superficial, and I have no doubt that they are really -foraminiferal organisms. This will appear more distinctly from the -sections in fig. 45 B, C, which represents an undescribed species -recently found by Mr. Weston, in the Upper Silurian limestone of -Ontario. - -[Illustration: Fig. 44. _Caunopora planulata, Hall--Devonian; showing -the radiating canals on a weathered surface._ (_After Hall._)] - -[Illustration: Fig. 45. _Cœnostroma--Guelph Limestone, Upper Silurian, -from a specimen collected by Mr. Weston, showing the canals._ - -(_a._) Surface with canals, natural size. (_b._) Vertical section, -natural size. (_c._) The same magnified, showing canals and laminæ.] - -There are probably many species of these curious fossils, but their -discrimination is difficult, and their nomenclature confused, so that -it would not be profitable to engage the attention of the reader -with it except in a note. Their state of preservation, however, is -so highly illustrative of that of Eozoon that a word as to this -will not be out of place. They are sometimes preserved merely by -infiltration with calcite or dolomite, and in this case it is most -difficult to make out their minute structures. Often they appear -merely as concentrically laminated masses which, but for their mode -of occurrence, might be regarded as mere concretions. In other cases -the cell-walls and pillars are perfectly silicified, and then they -form beautiful microscopic objects, especially when decalcified with -an acid. In still other cases, they are preserved like Eozoon, the -walls being calcareous and the chambers filled with silica. In this -state when weathered or decalcified they are remarkably like Eozoon, -but I have not met with any having their minute pores and tubes so -well preserved as in some of the Laurentian fossils. In many of them, -however, the growth and overlapping of the successive amœba-like coats -of sarcode can be beautifully seen, exactly as on the surface of a -decalcified piece of Eozoon. Those in my collection which most nearly -resemble the Laurentian specimens are from the older part of the Lower -Silurian series; but unfortunately their minute structures are not well -preserved. - -In the Silurian and Devonian ages, these Stromatoporæ evidently carried -out the same function as the Eozoon in the Laurentian. Winchell tells -us that in Michigan and Ohio single specimens can be found several feet -in diameter, and that they constitute the mass of considerable beds of -limestone. I have myself seen in Canada specimens a foot in diameter, -with a great number of laminæ. Lindberg[AK] has given a most vivid -account of their occurrence in the Isle of Gothland. He says that they -form beds of large irregular discs and balls, attaining a thickness of -five Swedish feet, and traceable for miles along the coast, and the -individual balls are sometimes a yard in diameter. In some of them the -structure is beautifully preserved. In others, or in parts of them, -it is reduced to a mass of crystalline limestone. This species is of -the Cœnostroma type, and is regarded by Lindberg as a coral, though -he admits its low type and resemblance to Protozoa. Its continuous -calcareous skeleton he rightly regards as fatal to its claim to be a -true sponge. Such a fossil, differing as it does in minute points of -structure from Eozoon, is nevertheless probably allied to it in no very -distant way, and a successor to its limestone-making function. Those -which most nearly approach to Foraminifera are those with thick and -solid calcareous laminæ, and with a radiating canal system; and one -of the most Eozoon-like I have seen, is a specimen of the undescribed -species already mentioned from the Guelph (Upper Silurian) limestone -of Ontario, collected by Mr. Weston, and now in the Museum of the -Geological Survey. I have attempted to represent its structures in fig. -44. - -[Footnote AK: _Transactions of Swedish Academy_, 1870.] - -[Illustration: Fig. 46. _Receptaculites, restored._ (_After Billings._) - -(_a._) Aperture. (_b._) Inner wall. (_c._) Outer wall. (_n._) Nucleus, -or primary chamber. (_v._) Internal cavity.] - -[Illustration: Fig. 47. _Diagram of Wall and Tubes of Receptaculites._ -(_After Billings._) - -(_b._) Inner wall. (_c._) Outer wall. (_d._) Section of plates. (_e._) -Pore of inner wall. (_f._) Canal of inner wall. (_g._) Radial stolon. -(_h._) Cyclical stolon. (_k._) Suture of plates of outer wall.] - -[Illustration: Fig. 48. _Receptaculites, Inner Surface of Outer Wall -with the Stolons remaining on its Surface._ (_After Billings._)] - -In the rocks extending from the Lower Silurian and perhaps from the -Upper Cambrian to the Devonian inclusive, the type and function of -Eozoon are continued by the Stromatoporæ, and in the earlier part of -this time these are accompanied by the Archæocyathids, and by another -curious form, more nearly allied to the latter than to Eozoon, the -_Receptaculites_. These curious and beautiful fossils, which sometimes -are a foot in diameter, consist, like Archæocyathus, of an outer and -inner coat enclosing a cavity; but these coats are composed of square -plates with pores at the corners, and they are connected by hollow -pillars passing in a regular manner from the outer to the inner coat. -They have been regarded by Salter as Foraminifers, while Billings -considers their nearest analogues to be the seed-like germs of some -modern silicious sponges. On the whole, if not Foraminifera, they must -have been organisms intermediate between these and sponges, and they -certainly constitute one of the most beautiful and complex types of -the ancient Protozoa, showing the wonderful perfection to which these -creatures attained at a very early period. (Figs. 46, 47, 48.) - -I might trace these ancient forms of foraminiferal life further up in -the geological series, and show how in the Carboniferous there are -nummulitic shells conforming to the general type of Eozoon, and in some -cases making up the mass of great limestones.[AL] Further, in the great -chalk series and its allied beds, and in the Lower Tertiary, there are -not only vast foraminiferal limestones, but gigantic species reminding -us of Stromatopora and Eozoon.[AM] Lastly, more diminutive species are -doing similar work on a great scale in the modern ocean. Thus we may -gather up the broken links of the chain of foraminiferal life, and -affirm that Eozoon has never wanted some representative to uphold its -family and function throughout all the vast lapse of geological time. - -[Footnote AL: _Fusulina_, as recently described by Carpenter, -_Archæodiscus_ of Brady, and the Nummulite recently found in the -Carboniferous of Belgium.] - -[Footnote AM: _Parkeria_ and _Loftusia_ of Carpenter.] - - -NOTES TO CHAPTER VI. - -(A.) Stromatoporidæ, Etc. - - For the best description of Archæocyathus, I may refer to _The - Palæozoic Fossils of Canada_, by Mr. Billings, vol. i. There also, - and in Mr. Salter's memoir in _The Decades of the Canadian Survey_, - will be found all that is known of the structure of Receptaculites. - For the American Stromatoporæ I may refer to Winchell's paper in the - _Proceedings of the American Association_, 1866; to Professor Hall's - Descriptions of New Species of Fossils from Iowa, _Report of the - State Cabinet, Albany_, 1872; and to the Descriptions of Canadian - Species by Dr. Nicholson, in his _Report on the Palæontology of - Ontario_, 1874. - - The genus Stromatopora of Goldfuss was defined by him as consisting - of laminæ of a solid and porous character, alternating and - contiguous, and constituting a hemispherical or sub-globose mass. - In this definition, the porous strata are really those of the - fossil, the alternating solid strata being the stony filling of the - chambers; and the descriptions of subsequent authors have varied - according as, from the state of preservation of the specimens or - other circumstances, the original laminæ or the filling of the spaces - attracted their attention. In the former case the fossil could be - described as consisting of laminæ made up of interlaced fibrils of - calcite, radiating from vertical pillars which connect the laminæ. - In the latter case, the laminæ, appear as solid plates, separated - by very narrow spaces, and perforated with round vertical holes - representing the connecting pillars. These Stromatoporæ range from - the Lower Silurian to the Devonian, inclusive, and many species have - been described; but their limits are not very definite, though there - are undoubtedly remarkable differences in the distances of the laminæ - and in their texture, and in the smooth or mammillated character - of the masses. Hall's genus Stromatocerium belongs to these forms, - and D'Orbigny's genus Sparsispongia refers to mammillated species, - sometimes with apparent oscula. - - Phillip's genus Caunopora was formed to receive specimens with - concentric cellular layers traversed by "long vermiform cylindrical - canals;" while Winchell's genus Cœnostroma includes species with - these vermiform canals arranged in a radiate manner, diverging from - little eminences in the concentric laminæ. The distinction between - these last genera does not seem to be very clear, and may depend - on the state of preservation of the specimens. A more important - distinction appears to exist between those that have a single - vertical canal from which the subordinate canals diverge, and those - that have groups of such canals. - - Some species of the Cœnostroma group have very dense calcareous - laminæ traversed by the canals; but it does not seem that any - distinction has yet been made between the proper wall and the - intermediate skeleton; and most observers have been prevented from - attending to such structures by the prevailing idea that these - fossils are either corals or sponges, while the state of preservation - of the more delicate tissues is often very imperfect. - - -(B.) Localities of Eozoon, or of Limestones supposed to contain it. - - In Canada the principal localities of Eozoon Canadense are at - Grenville, Petite Nation, the Calumets Rapids, Burgess, Tudor, and - Madoc. At the two last places the fossil occurs in beds which may be - on a somewhat higher horizon than the others. Mr. Vennor has recently - found specimens which have the general form of Eozoon, though the - minute structure is not preserved, at Dalhousie, in Lanark Co., - Ontario. One specimen from this place is remarkable from having been - mineralized in part by a talcose mineral associated with serpentine. - - I have examined specimens from Chelmsford, in Massachusetts, and from - Amity and Warren County, New York, the latter from the collection of - Professor D. S. Martin, which show the canals of Eozoon in a fair - state of preservation, though the specimens are fragmental, and do - not show the laminated structure. - - In European specimens of limestones of Laurentian age, from Tunaberg - and Fahlun in Sweden, and from the Western Islands of Scotland, I - have hitherto failed to recognise the characteristic structure of - the fossil. Connemara specimens have also failed to afford me any - satisfactory results, and specimens of a serpentine limestone from - the Alps, collected by M. Favre, and communicated to me by Dr. Hunt, - though in general texture they much resemble acervuline Eozoon, do - not show its minute structures. - -[Illustration: - Plate VII. - - _Untouched nature-print of part of a large specimen of Eozoon, from - Petite Nation._ - -The lighter portions are less perfect than in the original, owing to -the finer laminæ of serpentine giving way. The dark band at one side is -one of the deep lacunæ or oscula.] - - - - -CHAPTER VII. - -OPPONENTS AND OBJECTIONS. - - -The active objectors to the animal nature of Eozoon have been few, -though some of them have returned to the attack with a pertinacity and -determination which would lead one to believe that they think the most -sacred interests of science to be dependent on the annihilation of this -proto-foraminifer. I do not propose here to treat of the objections in -detail. I have presented the case of Eozoon on its own merits, and on -these it must stand. I may merely state that the objectors strive to -account for the existence of Eozoon by purely mineral deposition, and -that the complicated changes which they require to suppose are perhaps -the strongest indirect evidence for the necessity of regarding the -structures as organic. The reader who desires to appreciate this may -consult the notes to this chapter.[AN] - -[Footnote AN: Also Rowney and King's papers in _Journal Geological -Society_, August, 1866; and _Proceedings Irish Academy_, 1870 and 1871.] - -I confess that I feel disposed to treat very tenderly the position of -objectors. The facts I have stated make large demands on the faith -of the greater part even of naturalists. Very few geologists or -naturalists have much knowledge of the structure of foraminiferal -shells, or would be able under the microscope to recognise them with -certainty. Nor have they any distinct ideas of the appearances of such -structures under different kinds of preservation and mineralisation. -Further, they have long been accustomed to regard the so-called Azoic -rocks as not only destitute of organic remains, but as being in such -a state of metamorphism that these could not have been preserved had -they existed. Few, therefore, are able intelligently to decide for -themselves, and so they are called on to trust to the investigations -of others, and on their testimony to modify in a marked degree their -previous beliefs as to the duration of life on our planet. In these -circumstances it is rather wonderful that the researches made with -reference to Eozoon have met with so general acceptance, and that the -resurrection of this ancient inhabitant of the earth has not aroused -more of the sceptical tendency of our age. - -It must not be lost sight of, however, that in such cases there may -exist a large amount of undeveloped and even unconscious scepticism, -which shows itself not in active opposition, but merely in quietly -ignoring this great discovery, or regarding it with doubt, as an -uncertain or unestablished point in science. Such scepticism may best -be met by the plain and simple statements in the foregoing chapters, -and by the illustrations accompanying them. It may nevertheless be -profitable to review some of the points referred to, and to present -some considerations making the existence of Laurentian life less -anomalous than may at first sight be supposed. One of these is the -fact that the discovery of Eozoon brings the rocks of the Laurentian -system into more full harmony with the other geological formations. It -explains the origin of the Laurentian limestones in consistency with -that of similar rocks in the later periods, and in like manner it helps -us to account for the graphite and sulphides and iron ores of these old -rocks. It shows us that no time was lost in the introduction of life -on the earth. Otherwise there would have been a vast lapse of time in -which, while the conditions suitable to life were probably present, no -living thing existed to take advantage of these conditions. Further, it -gives a more simple beginning of life than that afforded by the more -complex fauna of the Primordial age; and this is more in accordance -with what we know of the slow and gradual introduction of new forms of -living things during the vast periods of Palæozoic time. In connection -with this it opens a new and promising field of observation in the -older rocks, and if this should prove fertile, its exploration may -afford a vast harvest of new forms to the geologists of the present and -coming time. This result will be in entire accordance with what has -taken place before in the history of geological discovery. It is not -very long since the old and semi-metamorphic sediments constituting the -great Silurian and Cambrian systems were massed together in geological -classifications as primitive or primary rocks, destitute or nearly -destitute of organic remains. The brilliant discoveries of Sedgwick, -Murchison, Barrande, and a host of others, have peopled these once -barren regions; and they now stretch before our wondering gaze in -the long vistas of early Palæozoic life. So we now look out from the -Cambrian shore upon the vast ocean of the Huronian and Laurentian, -all to us yet tenantless, except for the few organisms, which, like -stray shells cast upon the beach, or a far-off land dimly seen in the -distance, incite to further researches, and to the exploration of the -unknown treasures that still lie undiscovered. It would be a suitable -culmination of the geological work of the last half-century, and one -within reach at least of our immediate successors, to fill up this -great blank, and to trace back the Primordial life to the stage of -Eozoon, and perhaps even beyond this, to predecessors which may have -existed at the beginning of the Lower Laurentian, when the earliest -sediments of that great formation were laid down. Vast unexplored areas -of Laurentian and Huronian rocks exist in the Old World and the New. -The most ample facilities for microscopic examination of rocks may -now be obtained; and I could wish that one result of the publication -of these pages may be to direct the attention of some of the younger -and more active geologists to these fields of investigation. It is to -be observed also that such regions are among the richest in useful -minerals, and there is no reason why search for these fossils should -not be connected with other and more practically useful researches. On -this subject it will not be out of place to quote the remarks which I -made in one of my earlier papers on the Laurentian fossils:-- - -"This subject opens up several interesting fields of chemical, -physiological, and geological inquiry. One of these relates to the -conclusions stated by Dr. Hunt as to the probable existence of a -large amount of carbonic acid in the Laurentian atmosphere, and of -much carbonate of lime in the seas of that period, and the possible -relation of this to the abundance of certain low forms of plants and -animals. Another is the comparison already instituted by Professor -Huxley and Dr. Carpenter, between the conditions of the Laurentian and -those of the deeper parts of the modern ocean. Another is the possible -occurrence of other forms of animal life than Eozoon and Annelids, -which I have stated in my paper of 1864, after extensive microscopic -study of the Laurentian limestones, to be indicated by the occurrence -of calcareous fragments, differing in structure from Eozoon, but at -present of unknown nature. Another is the effort to bridge over, by -further discoveries similar to that of the _Eozoon Bavaricum_ of -Gümbel, the gap now existing between the life of the Lower Laurentian -and that of the Primordial Silurian or Cambrian period. It is scarcely -too much to say that these inquiries open up a new world of thought and -investigation, and hold out the hope of bringing us into the presence -of the actual origin of organic life on our planet, though this may -perhaps be found to have been Prelaurentian. I would here take the -opportunity of stating that, in proposing the name Eozoon for the -first fossil of the Laurentian, and in suggesting for the period the -name "Eozoic," I have by no means desired to exclude the possibility -of forms of life which may have been precursors of what is now to us -the dawn of organic existence. Should remains of still older organisms -be found in those rocks now known to us only by pebbles in the -Laurentian, these names will at least serve to mark an important stage -in geological investigation." - -But what if the result of such investigations should be to produce -more sceptics, or to bring to light mineral structures so resembling -Eozoon as to throw doubt upon the whole of the results detailed in -these chapters? I can fancy that this might be the first consequence, -more especially if the investigations were in the hands of persons -more conversant with minerals than with fossils; but I see no reason -to fear the ultimate results. In any case, no doubt, the value of the -researches hitherto made may be diminished. It is always the fate of -discoverers in Natural Science, either to be followed by opponents who -temporarily or permanently impugn or destroy the value of their new -facts, or by other investigators who push on the knowledge of facts and -principles so far beyond their standpoint that the original discoveries -are cast into the shade. This is a fatality incident to the progress of -scientific work, from which no man can be free; and in so far as such -matters are concerned, we must all be content to share the fate of the -old fossils whose history we investigate, and, having served our day -and generation to give place to others. If any part of our work should -stand the fire of discussion let us be thankful. One thing at least is -certain, that such careful surveys as those in the Laurentian rocks -of Canada which led to the discovery of Eozoon, and such microscopic -examinations as those by which it has been worked up and presented to -the public, cannot fail to yield good results of one kind or another. -Already the attention excited by the controversies about Eozoon, by -attracting investigators to the study of various microscopic and -imitative forms in rocks, has promoted the advancement of knowledge, -and must do so still more. For my own part, though I am not content to -base all my reputation on such work as I have done with respect to this -old fossil, I am willing at least to take the responsibility of the -results I have announced, whatever conclusions may be finally reached; -and in the consciousness of an honest effort to extend the knowledge -of nature, to look forward to a better fame than any that could result -from the most successful and permanent vindication of every detail -of our scientific discoveries, even if they could be pushed to a -point which no subsequent investigation in the same difficult line of -research would be able to overpass. - -Contenting myself with these general remarks, I shall, for the benefit -of those who relish geological controversy, append to this chapter a -summary of the objections urged by the most active opponents of the -animal nature of Eozoon, with the replies that may be or have been -given; and I now merely add (in fig. 49) a magnified camera tracing of -a portion of a lamina of Eozoon with its canals and tubuli, to show -more fully the nature of the structures in controversy. - -[Illustration: Fig. 49. _Portion of a thin Transverse Slice of a Lamina -of Eozoon, magnified, showing its structure, as traced with the camera._ - -(_a._) Nummuline wall of under side. (_b._) Intermediate skeleton with -canals. (_a´._) Nummuline wall of upper side. The two lower figures -show the lower and upper sides more highly magnified. The specimen is -one in which the canals are unusually well seen.] - -It may be well, however, to sum up the evidence as it has been -presented by Sir W. E. Logan, Dr. Carpenter, Dr. Hunt, and the author, -in a short and intelligible form; and I shall do so under a few brief -heads, with some explanatory remarks:-- - -1. The Lower Laurentian of Canada, a rock formation whose -distribution, age, and structure have been thoroughly worked out by -the Canadian Survey, is found to contain thick and widely distributed -beds of limestone, related to the other beds in the same way in which -limestones occur in the sediments of other geological formations. There -also occur in the same formation, graphite, iron ores, and metallic -sulphides, in such relations as to suggest the idea that the limestones -as well as these other minerals are of organic origin. - -2. In the limestones are found laminated bodies of definite form and -structure, composed of calcite alternating with serpentine and other -minerals. The forms of these bodies suggested a resemblance to the -Silurian Stromatoporæ, and the different mineral substances associated -with the calcite in the production of similar forms, showed that these -were not accidental or concretionary. - -3. On microscopic examination, it proved that the calcareous laminæ -of these forms were similar in structure to the shells of modern -and fossil Foraminifera, more especially those of the Rotaline and -Nummuline types, and that the finer structures, though usually filled -with serpentine and other hydrous silicates, were sometimes occupied -with calcite, pyroxene, or dolomite, showing that they must when recent -have been empty canals and tubes. - -4. The mode of filling thus suggested for the chambers and tubes of -Eozoon, is precisely that which takes place in modern Foraminifera -filled with glauconite, and in Palæozoic crinoids and corals filled -with other hydrous silicates. - -5. The type of growth and structure predicated of Eozoon from the -observed appearances, in its great size, its laminated and acervuline -forms, and in its canal system and tubulation, are not only in -conformity with those of other Foraminifera, but such as might be -expected in a very ancient form of that group. - -6. Indications exist of other organic bodies in the limestones -containing Eozoon, and also of the Eozoon being preserved not only in -reefs but in drifted fragmental beds as in the case of modern corals. - -7. Similar organic structures have been found in the Laurentian -limestones of Massachusetts and New York, and also in those of various -parts of Europe, and Dr. Gümbel has found an additional species in -rocks succeeding the Laurentian in age. - -8. The manner in which the structures of Eozoon are affected by the -faulting, development of crystals, mineral veins, and other effects of -disturbance and metamorphism in the containing rocks, is precisely that -which might be expected on the supposition that it is of organic origin. - -9. The exertions of several active and able opponents have failed to -show how, otherwise than by organic agency, such structures as those -of Eozoon can be formed, except on the supposition of pseudomorphism -and replacement, which must be regarded as chemically extravagant, and -which would equally impugn the validity of all fossils determined -by microscopic structure. In like manner all comparisons of these -structures with dendritic and other imitative forms have signally -failed, in the opinion of those best qualified to judge. - -Another and perhaps simpler way of putting the case is the -following:--Only three general modes of accounting for the existence -of Eozoon have been proposed. The first is that of Professors King and -Rowney, who regard the chambers and canals filled with serpentine as -arising from the erosion or partial dissolving away of serpentine and -its replacement by calcite. The objections to this are conclusive. -It does not explain the nummuline wall, which has to be separately -accounted for by confounding it, contrary to the observed facts, -with the veins of fibrous serpentine which actually pass through -cracks in the fossil. Such replacement is in the highest degree -unlikely on chemical grounds, and there is no evidence of it in the -numerous serpentine grains, nodules, and bands in the Laurentian -limestones. On the other hand, the opposite replacement, that of -limestone by serpentine, seems to have occurred. The mechanical -difficulties in accounting for the delicate canals on this theory are -also insurmountable. Finally, it does not account for the specimens -preserved in pyroxene and other silicates, and in dolomite and calcite. -A second mode of accounting for the facts is that the Eozoon forms are -merely peculiar concretions. But this fails to account for their great -difference from the other serpentine concretions in the same beds, and -for their regularity of plan and the delicacy of their structure, and -also for minerals of different kinds entering into their composition, -and still presenting precisely the same forms and structures. The only -remaining theory is that of the filling of cavities by infiltration -with serpentine. This accords with the fact that such infiltration by -minerals akin to serpentine exists in fossils in later rocks. It also -accords with the known aqueous origin of the serpentine nodules and -bands, the veins of fibrous serpentine, and the other minerals found -filling the cavities of Eozoon. Even the pyroxene has been shown by -Hunt to exist in the Laurentian in veins of aqueous origin. The only -difficulty existing on this view is how a calcite skeleton with such -chambers, canals, and tubuli could be formed; and this is solved by the -discovery that all these facts correspond precisely with those to be -found in the shells of modern oceanic Foraminifera. The existence then -of Eozoon, its structure, and its relations to the containing rocks and -minerals being admitted, no rational explanation of its origin seems at -present possible other than that advocated in the preceding pages. - -If the reader will now turn to Plate VIII., page 207, he will find some -interesting illustrations of several very important facts bearing on -the above arguments. Fig. 1 represents a portion of a very thin slice -of a specimen traversed by veins of fibrous serpentine or chrysotile, -and having the calcite of the walls more broken by cleavage planes -than usual. The portion selected shows a part of one of the chambers -filled with serpentine, which presents the usual curdled aspect -almost impossible to represent in a drawing (_s_). It is traversed -by a branching vein of chrysotile (_s_´), which, where cut precisely -parallel to its fibres, shows clear fine cross lines, indicating the -sides of its constituent prisms, and where the plane of section has -passed obliquely to its fibres, has a curiously stippled or frowsy -appearance. On either side of the serpentine band is the nummuline -or proper wall, showing under a low power a milky appearance, which, -with a higher power, becomes resolved into a tissue of the most -beautiful parallel threads, representing the filling of its tubuli. -Nothing can be more distinct than the appearances presented by this -wall and the chrysotile vein, under every variety of magnifying power -and illumination; and all who have had an opportunity of examining my -specimens have expressed astonishment that appearances so dissimilar -should have been confounded with each other. On the lower side two -indentations are seen in the proper wall (_c_). These are connected -with the openings into small subordinate chamberlets, one of which is -in part included in the thickness of the slice. At the upper and lower -parts of the figure are seen portions of the intermediate skeleton -traversed by canals, which in the lower part are very large, though -from the analogy of other specimens it is probable that they have in -their interstices minute canaliculi not visible in this slice. Fig. -2, from the same specimen, shows the termination of one of the canals -against the proper wall, its end expanding into a wide disc of sarcode -on the surface of the wall, as may be seen in similar structures in -modern Foraminifera. In this specimen the canals are beautifully smooth -and cylindrical, but they sometimes present a knotted or jointed -appearance, especially in specimens decalcified by acids, in which -perhaps some erosion has taken place. They are also occasionally -fringed with minute crystals, especially in those specimens in which -the calcite has been partially replaced with other minerals. Fig. 3 -shows an example of faulting of the proper wall, an appearance not -infrequently observed; and it also shows a vein chrysotile crossing the -line of fault, and not itself affected by it--a clear evidence of its -posterior origin. Figs. 4 and 5 are examples of specimens having the -canals filled with dolomite, and showing extremely fine canals in the -interstices of the others: an appearance observed only in the thicker -parts of the skeleton, and when these are very well preserved. These -dolomitized portions require some precautions for their observation, -either in slices or decalcified specimens, but when properly managed -they show the structures in very great perfection. The specimen in fig. -5 is from an abnormally thick portion of intermediate skeleton, having -unusually thick canals, and referred to in a previous chapter. - -One object which I have in view in thus minutely directing attention -to these illustrations, is to show the nature of the misapprehensions -which may occur in examining specimens of this kind, and at the same -time the certainty which may be attained when proper precautions are -taken. I may add that such structures as those referred to are best -seen in extremely thin slices, and that the observer must not expect -that every specimen will exhibit them equally well. It is only by -preparing and examining many specimens that the best results can be -obtained. It often happens that one specimen is required to show well -one part of the structures, and a different one to show another; and -previous to actual trial, it is not easy to say which portion of -the structures any particular fragment will show most clearly. This -renders it somewhat difficult to supply one's friends with specimens. -Really good slices can be prepared only from the best material and by -skilled manipulators; imperfect slices may only mislead; and rough -specimens may not be properly prepared by persons unaccustomed to the -work, or if so prepared may not turn out satisfactory, or may not be -skilfully examined. These difficulties, however, Eozoon shares with -other specimens in micro-geology, and I have experienced similar -disappointments in the case of fossil wood. - -In conclusion of this part of the subject, and referring to the notes -appended to this chapter for further details, I would express the hope -that those who have hitherto opposed the interpretation of Eozoon as -organic, and to whose ability and honesty of purpose I willingly bear -testimony, will find themselves enabled to acknowledge at least the -reasonable probability of that interpretation of these remarkable forms -and structures. - - -NOTES TO CHAPTER VII. - -(A.) Objections of Profs. King and Rowney. - -_Trans. Royal Irish Academy, July, 1869._[AO] - -[Footnote AO: Reprinted in the _Annals and Magazine of Natural -History_, May, 1874.] - - The following summary, given by these authors, may be taken as - including the substance of their objections to the animal nature of - Eozoon. I shall give them in their words and follow them with short - answers to each. - - "1st. The serpentine in ophitic rocks has been shown to present - appearances which can only be explained on the view that it undergoes - structural and chemical changes, causing it to pass into variously - subdivided states, and etching out the resulting portions into a - variety of forms--grains and plates, with lobulated or segmented - surfaces--fibres and aciculi--simple and branching configurations. - Crystals of malacolite, often associated with the serpentine, - manifest some of these changes in a remarkable degree. - - "2nd. The 'intermediate skeleton' of Eozoon (which we hold to be - the calcareous matrix of the above lobulated grains, etc.) is - completely paralleled in various crystalline rocks--notably marble - containing grains of coccolite (Aker and Tyree), pargasite (Finland), - chondrodite (New Jersey, etc.) - - "3rd. The 'chamber casts' in the acervuline variety of Eozoon are - more or less paralleled by the grains of the mineral silicates in the - pre-cited marbles. - - "4th. The 'chamber casts' being composed occasionally of loganite and - malacolite, besides serpentine, is a fact which, instead of favouring - their organic origin, as supposed, must be held as a proof of their - having been produced by mineral agencies; inasmuch as these three - silicates have a close pseudomorphic relationship, and may therefore - replace one another in their naturally prescribed order. - - "5th. Dr. Gümbel, observing rounded, cylindrical, or tuberculated - grains of coccolite and pargasite in crystalline calcareous marbles, - considered them to be 'chamber casts,' or of organic origin. We have - shown that such grains often present crystalline planes, angles, and - edges; a fact clearly proving that they were originally simple or - compound crystals that have undergone external decretion by chemical - or solvent action. - - "6th. We have adduced evidences to show that the 'nummuline layer' in - its typical condition--that is, consisting of cylindrical aciculi, - separated by interspaces filled with calcite--has originated directly - from closely packed fibres; these from chrysotile or asbestiform - serpentine; this from incipiently fibrous serpentine; and the latter - from the same mineral in its amorphous or structureless condition. - - "7th. The 'nummuline layer,' in its typical condition, unmistakably - occurs in cracks or fissures, both in Canadian and Connemara ophite. - - "8th. The 'nummuline layer' is paralleled by the fibrous coat which - is occasionally present on the surface of grains of chondrodite. - - "9th. We have shown that the relative position of two superposed - asbestiform layers (an _upper_ and an _under_ 'proper wall'), and the - admitted fact of their component aciculi often passing continuously - and without interruption from one 'chamber cast' to another, to the - exclusion of the 'intermediate skeleton,' are totally incompatible - with the idea of the 'nummuline layer' having resulted from - pseudopodial tubulation. - - "10th. The so-called 'stolons' and 'passages of communication - exactly corresponding with those described in _Cycloclypeus_,' - have been shown to be tabular crystals and variously formed bodies, - belonging to different minerals, wedged crossways or obliquely in the - calcareous interspaces between the grains and plates of serpentine. - - "11th. The 'canal system' is composed of serpentine, or malacolite. - Its typical kinds in the first of these minerals may be traced in - all stages of formation out of plates, prisms, and other solids, - undergoing a process of superficial decretion. Those in malacolite - are made up of crystals--single, or aggregated together--that have - had their planes, angles, and edges rounded off; or have become - further reduced by some solvent. - - "12th. The 'canal system' in its remarkable branching varieties is - completely paralleled by crystalline configurations in the coccolite - marble of Aker, in Sweden; and in the crevices of a crystal of spinel - imbedded in a calcitic matrix from Amity, New York. - - "13th. The _configurations_, presumed to represent the 'canal - systems,' are _totally without any regularity_ of form, of relative - size, or of arrangement; and they occur independently of and apart - from other 'eozoonal features' (Amity, Boden, etc.); facts not only - demonstrating them to be purely mineral products, but which strike at - the root of the idea that they are of organic origin. - - "14th. In answer to the argument that as all the foregoing 'eozoonal - features' are occasionally found together in ophite, the combination - must be considered a conclusive evidence of their organic origin, - we have shown, from the composition, physical characters, and - circumstances of occurrence and association of their component - serpentine, that they represent the structural and chemical changes - which are eminently and peculiarly characteristic of this mineral. - It has also been shown that the combination is paralleled to a - remarkable extent in chondrodite and its calcitic matrix. - - "15th. The 'regular alternation of lamellæ of calcareous and - silicious minerals' (respectively representing the 'intermediate - skeleton' and 'chamber casts') occasionally seen in ophite, and - considered to be a 'fundamental fact' evidencing an organic - arrangement, is proved to be a _mineralogical_ phenomenon by the - fact that a similar alternation occurs in amphiboline-calcitic - marbles, and gneissose rocks. - - "16th. In order to account for certain _untoward_ difficulties - presented by the configurations forming the 'canal system,' and - the aciculi of the 'nummuline layer'--that is, when they occur as - '_solid bundles_'--or are '_closely packed_'--or '_appear to be - glued together_'--Dr. Carpenter has proposed the theory that the - sarcodic extensions which they are presumed to represent have been - 'turned into stone' (a 'silicious mineral') 'by Nature's cunning' - ('just as the sarcodic layer on the surface of the shell of living - Foraminifers is formed by the spreading out of _coalesced_ bundles - of the pseudopodia that have emerged from the chamber wall')--'by - a process of chemical substitution _before_ their destruction by - ordinary decomposition.' We showed this quasi-alchymical theory to be - altogether unscientific. - - "17th. The 'silicious mineral' (serpentine) has been analogued with - those forming the variously-formed casts (in 'glauconite,' etc.) - of recent and fossil Foraminifers. We have shown that the mineral - silicates of Eozoon have no relation whatever to the substances - composing such casts. - - "18th. Dr. Hunt, in order to account for the serpentine, loganite, - and malacolite, being the presumed in-filling substances of Eozoon, - has conceived the 'novel doctrine,' that such minerals were - _directly_ deposited in the ocean waters in which this 'fossil' - lived. We have gone over all his evidences and arguments without - finding _one_ to be substantiated. - - "19th. Having investigated the alleged cases of 'chambers' and - 'tubes' occurring 'filled with calcite,' and presumed to be 'a - conclusive answer to' our 'objections,' we have shown that there are - the strongest grounds for removing them from the category of reliable - evidences on the side of the organic doctrine. The Tudor specimen has - been shown to be equally unavailable. - - "20th. The occurrence of the best preserved specimens of Eozoon - Canadense in rocks that are in a '_highly crystalline condition_' - (Dawson) must be accepted as a fact utterly fatal to its organic - origin. - - "21st. The occurrence of 'eozoonal features' _solely_ in crystalline - or metamorphosed rocks, belonging to the Laurentian, the Lower - Silurian, and the Liassic systems--never in ordinary unaltered - deposits of these and the intermediate systems--must be assumed as - completely demonstrating their purely mineral origin." - - The answers already given to these objections may be summed up - severally as follows:-- - - 1st. This is a mere hypothesis to account for the forms presented by - serpentine grains and by Eozoon. Hunt has shown that it is untenable - chemically, and has completely exploded it in his recent papers on - Chemistry and Geology.[AP] My own observations show that it does not - accord with the mode of occurrence of serpentine in the Laurentian - limestones of Canada. - -[Footnote AP: Boston, 1874.] - - 2nd. Some of the things stated to parallel the intermediate skeleton - of Eozoon, are probably themselves examples of that skeleton. Others - have been shown to have no resemblance to it. - - 3rd. The words "more or less" indicate the precise value of this - statement, in a question of comparison between mineral and organic - structures. So the prismatic structure of satin-spar may be said - "more or less" to resemble that of a shell, or of the cells of a - Stenopora. - - 4th. This overlooks the filling of chamber casts with pyroxene, - dolomite, or limestone. Even in the case of loganite this objection - is of no value unless it can be applied equally to the similar - silicates which fill cavities of fossils[AQ] in the Silurian - limestones and in the green-sand. - -[Footnote AQ: See for a full discussion of this subject Dr. Hunt's -"Papers" above referred to.] - - 5th. Dr. Gümbel's observations are those of a highly skilled and - accurate observer. Even if crystalline forms appear in "chamber - casts," this is as likely to be a result of the injury of organic - structures by crystallization, as of the partial effacement of - crystals by other actions. Crystalline faces occur abundantly in many - undoubted fossil woods and corals; and crystals not unfrequently - cross and interfere with the structures in such specimens. - - 6th. On the contrary, the Canadian specimens prove clearly that the - veins of chrysotile have been filled subsequently to the existence of - Eozoon in its present state, and that there is no connection whatever - between them and the Nummuline wall. - - 7th. This I have never seen in all my examinations of Eozoon. The - writers must have mistaken veins of fibrous serpentine for the - nummuline wall. - - 8th. Only if such grains of chondrodite are themselves casts of - foraminiferal chambers. But Messrs. King and Rowney have repeatedly - figured mere groups of crystals as examples of the nummuline wall. - - 9th. Dr. Carpenter has shown that this objection depends on a - misconception of the structure of modern Foraminifera, which show - similar appearances. - - 10th. That disseminated crystals occur in the Eozoon limestones is a - familiar fact, and one paralleled in many other more or less altered - organic limestones. Foreign bodies also occur in the chambers filled - with loganite and other minerals; but these need not any more be - confounded with the pillars and walls connecting the laminæ than - the sand filling a dead coral with its lamellæ. Further, it is well - known that foreign bodies are often contained both in the testa and - chambers even of recent Foraminifera. - - 11th. The canal system is not always filled with serpentine or - malacolite; and when filled with pyroxene, dolomite, or calcite, the - forms are the same. The irregularities spoken of are perhaps more - manifest in the serpentine specimens, because this mineral has in - places encroached on or partially replaced the calcite walls. - - 12th. If this is true of the Aker marble, then it must contain - Eozoon; and specimens of the Amity limestone which I have examined, - certainly contain large fragments of Eozoon. - - 13th. The configuration of the canal system is quite definite, - though varying in coarseness and fineness. It is not known to occur - independently of the forms of Eozoon except in fragmental deposits. - - 14th. The argument is not that they are "occasionally found together - in ophite," but that they are found together in specimens preserved - by different minerals, and in such a way as to show that all these - minerals have filled chambers, canals, and tubuli, previously - existing in a skeleton of limestone. - - 15th. The lamination of Eozoon is not like that of any rock, but - a strictly limited and definite form, comparable with that of - Stromatopora. - - 16th. This I pass over, as a mere captious criticism of modes of - expression used by Dr. Carpenter. - - 17th. Dr. Hunt, whose knowledge of chemical geology should give - the greatest weight to his judgment, maintains the deposition of - serpentine and loganite to have taken place in a manner similar to - that of jollyte and glauconite in undoubted fossils: and this would - seem to be a clear deduction from the facts he has stated, and from - the chemical character of the substances. My own observations of the - mode of occurrence of serpentine in the Eozoon limestones lead me to - the same result. - - 18th. Dr. Hunt's arguments on the subject, as recently presented - in his _Papers on Chemistry and Geology_, need only be studied by - any candid and competent chemist or mineralogist to lead to a very - different conclusion from that of the objectors. - - 19th. This is a mere statement of opinion. The fact remains that the - chambers and canals are sometimes filled with calcite. - - 20th. That the occurrence of Eozoon in crystalline limestones is - "utterly fatal" to its claims to organic origin can be held only by - those who are utterly ignorant of the frequency with which organic - remains are preserved in highly crystalline limestones of all ages. - In addition to other examples mentioned above, I may state that the - curious specimen of Cœnostroma from the Guelph limestone figured - in Chapter VI., has been converted into a perfectly crystalline - dolomite, while its canals and cavities have been filled with - calcite, since weathered out. - - 21st. This limited occurrence is an assumption contrary to facts. - It leaves out of account the Tudor specimens, and also the abundant - occurrence of the Stromatoporoid successors of Eozoon in the - Silurian and Devonian. Further, even if the Eozoon were limited to - the Laurentian, this would not be remarkable; and since all the - Laurentian rocks known to us are more or less altered, it could not - in that case occur in unaltered rocks. - - I have gone over these objections seriatim, because, though - individually weak, they have an imposing appearance in the aggregate, - and have been paraded as a conclusive settlement of the questions - at issue. They have even been reprinted in the year just past in an - English journal of some standing, which professes to accept only - original contributions to science, but has deviated from its rule in - their favour. I may be excused for adding a portion of my original - argument in opposition to these objections, as given more at length - in the _Transactions of the Irish Academy_. - - 1. I object to the authors' mode of stating the question at issue, - whereby they convey to the reader the impression that this is merely - to account for the occurrence of certain peculiar forms in ophite. - - With reference to this, it is to be observed that the attention of - Sir William Logan, and of the writer, was first called to Eozoon - by the occurrence in Laurentian rocks of definite forms resembling - the Silurian _Stromatoporæ_, and dissimilar from any concretions or - crystalline structures found in these rocks. With his usual sagacity, - Sir William added to these facts the consideration that the mineral - substances occurring is these forms were so dissimilar as to suggest - that the forms themselves must be due to some extraneous cause rather - than to any crystalline or segregative tendency of their constituent - minerals. These specimens, which were exhibited by Sir William as - probably fossils, at the meeting of the American Association in - 1859, and noticed with figures in the Report of the Canadian Survey - for 1863, showed under the microscope no minute structures. The - writer, who had at the time an opportunity of examining them, stated - his belief that if fossils, they would prove to be not Corals but - Protozoa. - - In 1864, additional specimens having been obtained by the Survey, - slices were submitted to the writer, in which he at once detected - a well-marked canal-system, and stated, decidedly, his belief that - the forms were organic and foraminiferal. The announcement of this - discovery was first made by Sir W. E. Logan, in _Silliman's Journal_ - for 1864. So far, the facts obtained and stated related to definite - forms mineralised by loganite, serpentine, pyroxene, dolomite, and - calcite. But before publishing these facts in detail, extensive - series of sections of all the Laurentian limestones, and of those - of the altered Quebec group of the Green Mountain range, were made, - under the direction of Sir W. E. Logan and Dr. Hunt, and examined - microscopically. Specimens were also decalcified by acids, and - subjected to chemical examination by Dr. Sterry Hunt. The result was - the conviction that the definite laminated forms must be organic, - and further, that there exist in the Laurentian limestones fragments - of such forms retaining their structure, and also other fragments, - probably organic, but distinct from Eozoon. These conclusions were - submitted to the Geological Society of London, in 1864, after the - specimens on which they were based had been shown to Dr. Carpenter - and Professor T. R. Jones, the former of whom detected in some of - the specimens an additional foraminiferal structure--that of the - tubulation of the proper wall, which I had not been able to make out. - Subsequently, in rocks at Tudor, of somewhat later age than those - of the Lower Laurentian at Grenville, similar structures were found - in limestones not more metamorphic than many of those which retain - fossils in the Silurian system. I make this historical statement in - order to place the question in its true light, and to show that it - relates to the organic origin of certain definite mineral masses, - exhibiting, not only the external forms of fossils, but also their - internal structure. - - In opposition to these facts, and to the careful deductions drawn - from them, the authors of the paper under consideration maintain that - the structures are mineral and crystalline. I believe that in the - present state of science such an attempt to return to the doctrine - of "plastic-force" as a mode of accounting for fossils would not - be tolerated for a moment, were it not for the great antiquity and - highly crystalline condition of the rocks in which the structures - are found, which naturally create a prejudice against the idea of - their being fossiliferous. That the authors themselves feel this is - apparent from the slight manner in which they state the leading facts - above given, and from their evident anxiety to restrict the question - to the mode of occurrence of serpentine in limestone, and to ignore - the specimens of Eozoon preserved under different mineral conditions. - - 2. With reference to the general form of Eozoon and its structure - on the large scale, I would call attention to two admissions of - the authors of the paper, which appear to me to be fatal to their - case:--First, they admit, at page 533 [_Proceedings_, vol. x.], - their "inability to explain satisfactorily" the alternating layers - of carbonate of lime and other minerals in the typical specimens of - Canadian Eozoon. They make a feeble attempt to establish an analogy - between this and certain concentric concretionary layers; but the - cases are clearly not parallel, and the laminæ of the Canadian - Eozoon present connecting plates and columns not explicable on any - concretionary hypothesis. If, however, they are unable to explain the - lamellar structure alone, as it appeared to Logan in 1859, is it not - rash to attempt to explain it away now, when certain minute internal - structures, corresponding to what might have been expected on the - hypothesis of its organic origin, are added to it? If I affirm that - a certain mass is the trunk of a fossil tree, and another asserts - that it is a concretion, but professes to be unable to account for - its form and its rings of growth, surely his case becomes very weak - after I have made a slice of it, and have shown that it retains the - structure of wood. - - Next, they appear to admit that if specimens occur wholly composed - of carbonate of lime, their theory will fall to the ground. Now such - specimens do exist. They treat the Tudor specimen with scepticism as - probably "strings of segregated calcite." Since the account of that - specimen was published, additional fragments have been collected, so - that new slices have been prepared. I have examined these with care, - and am prepared to affirm that the chambers in these specimens are - filled with a dark-coloured limestone not more crystalline than is - usual in the Silurian rocks, and that the chamber walls are composed - of carbonate of lime, with the canals filled with the same material, - except where the limestone filling the chambers has penetrated into - parts of the larger ones. I should add that the stratigraphical - researches of Mr. Vennor, of the Canadian Survey, have rendered it - probable that the beds containing these fossils, though unconformably - underlying the Lower Silurian, overlie the Lower Laurentian of the - locality, and are, therefore, probably Upper Laurentian, or perhaps - Huronian, so that the Tudor specimens may approach in age to Gümbel's - Eozoon Bavaricum.[AR] - -[Footnote AR: I may now refer in addition to the canals filled with -calcite and dolomite, detected by Dr. Carpenter and myself in specimens -from Petite Nation, and mentioned in a previous chapter. See also Plate -VIII.] - - Further, the authors of the paper have no right to object to our - regarding the laminated specimen as "typical" Eozoon. If the question - were as to _typical ophite_ the case would be different; but the - question actually is as to certain well-defined forms which we regard - as fossils, and allege to have organic structure on the small scale, - as well as lamination on the large scale. We profess to account for - the acervuline forms by the irregular growth at the surface of the - organisms, and by the breaking of them into fragments confusedly - intermingled in great thicknesses of limestone, just as fragments of - corals occur in Palæozoic limestones; but we are under no obligation - to accept irregular or disintegrated specimens as typical; and when - objectors reason from these fragments, we have a right to point to - the more perfect examples. It would be easy to explain the loose - cells of _Tetradium_ which characterize the bird's-eye limestone - of the Lower Silurian of America, as crystalline structures; but - a comparison with the unbroken masses of the same coral, shows - their true nature. I have for some time made the minute structure - of Palæozoic limestones a special study, and have described some - of them from the Silurian formations of Canada.[AS] I possess now - many additional examples, showing fragments of various kinds of - fossils preserved in these limestones, and recognisable only by the - infiltration of their pores with different silicious minerals. It can - also be shown that in many cases the crystallization of the carbonate - of lime, both of the fossils themselves and of their matrix, has - not interfered with the perfection of the most minute of these - structures. - -[Footnote AS: In the _Canadian Naturalist_.] - - The fact that the chambers are usually filled with silicates is - strangely regarded by the authors as an argument against the organic - nature of Eozoon. One would think that the extreme frequency of - silicious fillings of the cavities of fossils, and even of silicious - replacement of their tissues, should have prevented the use of such - an argument, without taking into account the opposite conclusions to - be drawn from the various kinds of silicates found in the specimens, - and from the modern filling of Foraminifera by hydrous silicates, as - shown by Ehrenberg, Mantell, Carpenter, Bailey, and Pourtales.[AT] - Further, I have elsewhere shown that the loganite is proved by its - texture to have been a fragmental substance, or at least filled - with loose _debris_; that the Tudor specimens have the cavities - filled with a sedimentary limestone, and that several fragmental - specimens from Madoc are actually wholly calcareous. It is to be - observed, however, that the wholly calcareous specimens present - great difficulties to an observer; and I have no doubt that they are - usually overlooked by collectors in consequence of their not being - developed by weathering, or showing any obvious structure in fresh - fractures. - -[Footnote AT: _Quarterly Journal Geol. Society_, 1864.] - - 3. With regard to the canal system, the authors persist in - confusing the casts of it which occur in serpentine with "metaxite" - concretions, and in likening them to dendritic crystallizations of - silver, etc., and coralloidal forms of carbonate of lime. In answer - to this, I think it quite sufficient to say that I fail to perceive - the resemblance as other than very imperfectly imitative. I may add, - that the case is one of the occurrence of a canal structure in forms - which on other grounds appear to be organic, while the concretionary - forms referred to are produced under diverse conditions, none of - them similar to those of which evidence appears in the specimens of - Eozoon. With the singular theory of pseudomorphism, by means of which - the authors now supplement their previous objections, I leave Dr. - Hunt to deal. - - 4. With respect to the proper wall and its minute tubulation, the - essential error of the authors consists in confounding it with - fibrous and acicular crystals, and in maintaining that because the - tubuli are sometimes apparently confused and confluent they must - be inorganic. With regard to the first of these positions, I may - repeat what I have stated in former papers--that the true cell-wall - presents minute cylindrical processes traversing carbonate of lime, - and usually nearly parallel to each other, and often slightly - bulbose at the extremity. Fibrous serpentine, on the other hand, - appears as angular crystals, closely packed together, while the - numerous spicular crystals of silicious minerals which often appear - in metamorphic limestones, and may be developed by decalcification, - appear as sharp angular needles usually radiating from centres or - irregularly disposed. Their own plate (Ophite from Skye, King and - Rowney's Paper, _Proc. R. I. A._, vol. x.), is an eminent example - of this; and whatever the nature of the crystals represented, they - have no appearance of being true tubuli of Eozoon. I have very often - shown microscopists and geologists the cell-wall along with veins of - chrysotile and coatings of acicular crystals occurring in the same or - similar limestones, and they have never failed at once to recognise - the difference, especially under high powers. - - I do not deny that the tubulation is often imperfectly preserved, - and that in such cases the casts of the tubuli may appear to be - glued together by concretions of mineral matter, or to be broken - or imperfect. But this occurs in all fossils, and is familiar to - any microscopist examining them. How difficult is it in many cases - to detect the minute structure of Nummulites and other fossil - Foraminifera? How often does a specimen of fossil wood present in one - part distorted and confused fibres or mere crystals, with the remains - of the wood forming phragmata between them, when in other parts it - may show the most minute structures in perfect preservation? But - who would use the disintegrated portions to invalidate the evidence - of the parts better preserved? Yet this is precisely the argument - of Professors King and Rowney, and which they have not hesitated - in using in the case of a fossil so old as Eozoon, and so often - compressed, crushed, and partly destroyed by mineralization. - - I have in the above remarks confined myself to what I regard as - absolutely essential by way of explanation and defence of the - organic nature of Eozoon. It would be unprofitable to enter into the - multitude of subordinate points raised by the authors, and their - theory of mineral pseudomorphism is discussed by my friend Dr. Hunt; - but I must say here that this theory ought, in my opinion, to afford - to any chemist a strong presumption against the validity of their - objections, especially since it confessedly does not account for all - the facts, while requiring a most complicated series of unproved and - improbable suppositions. - - The only other new features in the communication to which this note - refers are contained in the "supplementary note." The first of - these relates to the grains of coccolite in the limestone of Aker, - in Sweden. Whether or not these are organic, they are apparently - different from _Eozoon Canadense_. They, no doubt, resemble the - grains referred to by Gümbel as possibly organic, and also similar - granular objects with projections which, in a previous paper, I have - described from Laurentian limestones in Canada. These objects are of - doubtful nature; but if organic, they are distinct from Eozoon. The - second relates to the supposed crystals of malacolite from the same - place. Admitting the interpretation given of these to be correct, - they are no more related to Eozoon than are the curious vermicular - crystals of a micaceous mineral which I have noticed in the Canadian - limestones. - - The third and still more remarkable case is that of a spinel from - Amity, New York, containing calcite in its crevices, including a - perfect canal system preserved in malacolite. With reference to - this, as spinels of large size occur in veins in the Laurentian - rocks, I am not prepared to say that it is absolutely impossible that - fragments of limestone containing Eozoon may not be occasionally - associated with them in their matrix. I confess, however, that - until I can examine such specimens, which I have not yet met with, - I cannot, after my experience of the tendencies of Messrs. Rowney - and King to confound other forms with those of Eozoon, accept their - determinations in a matter so critical and in a case so unlikely.[AU] - -[Footnote AU: I have since ascertained that Laurentian limestone found -at Amity, New York, and containing spinels, does hold fragments of the -intermediate skeleton of Eozoon. The limestone may have been originally -a mass of fragments of this kind with the aluminous and magnesian -material of the spinel in their interstices.] - - If all specimens of Eozoon were of the acervuline character, the - comparison of the chamber-casts with concretionary granules might - have some plausibility. But it is to be observed that the laminated - arrangement is the typical one; and the study of the larger - specimens, cut under the direction of Sir W. E. Logan, shows that - these laminated forms must have grown on certain strata-planes before - the deposition of the overlying beds, and that the beds are, in part, - composed of the broken fragments of similar laminated structures. - Further, much of the apparently acervuline Eozoon rock is composed - of such broken fragments, the interstices between which should not - be confounded with the chambers: while the fact that the serpentine - fills such interstices as well as the chambers shows that its - arrangement is not concretionary. Again, these chambers are filled in - different specimens with serpentine, pyroxene, loganite, calcareous - spar, chondrodite, or even with arenaceous limestone. It is also to - be observed that the examination of a number of limestones, other - than Canadian, by Messrs. King and Rowney, has obliged them to admit - that the laminated forms in combination with the canal-system are - "essentially Canadian," and that the only instances of structures - clearly resembling the Canadian specimens are afforded by limestones - Laurentian in age, and in some of which (as, for instance, in those - of Bavaria and Scandinavia) Carpenter and Gümbel have actually found - the structure of Eozoon. The other serpentine-limestones examined - (for example, that of Skye) are admitted to fail in essential points - of structure; and the only serpentine believed to be of eruptive - origin examined by them is confessedly destitute of all semblance - of Eozoon. Similar results have been attained by the more careful - researches of Prof. Gümbel, whose paper is well deserving of study by - all who have any doubts on this subject. - - -(B.) Reply by Dr. Hunt to Chemical Objections--(_Ibid._). - - "In the _Proceedings of the Royal Irish Academy_, for July 12, - 1869, Messrs. King and Rowney have given us at length their latest - corrected views on various questions connected with Eozoon Canadense. - Leaving to my friend, Dr. Dawson, the discussion of the zoological - aspects of the question, I cannot forbear making a few criticisms - on the chemical and mineralogical views of the authors. The problem - which they had before them was to explain the occurrence of certain - forms which, to skilled observers, like Carpenter, Dawson, and - Rupert Jones, appear to possess all the structural character of the - calcareous skeleton of a foraminiferal organism, and moreover to - show how it happens that these forms of crystalline carbonate of - lime are associated with serpentine in such a way as to lead these - observers to conclude that this hydrous silicate of magnesia filled - and enveloped the calcareous skeleton, replacing the perishable - sarcode. The hypothesis now put forward by Messrs. King and Rowney - to explain the appearances in question, is, that all this curiously - arranged serpentine, which appears to be a cast of the interior of a - complex foraminiferal organism, has been shaped or sculptured out of - plates, prisms, and other solids of serpentine, by "the erosion and - incomplete waste of the latter, _the definite shapes_ being residual - portions of the solid that have not completely disappeared." The - calcite which limits these definite shapes, or, in other words, what - is regarded as the calcareous skeleton of Eozoon, is a 'replacement - pseudomorph' of calcite taking the place of the wasted and eroded - serpentine. It was not a calcareous fossil, filled and surrounded - by the serpentine, but was formed in the midst of the serpentine - itself, by a mysterious agency which dissolved away this mineral to - form a mould, in which the calcite was cast. This marvellous process - can only be paralleled by the operations of that plastic force in - virtue of which sea-shells were supposed by some old naturalists - to be generated in the midst of rocky strata. Such equivocally - formed fossils, whether oysters or Foraminifers, may well be termed - _pseudomorphs_, but we are at a loss to see with what propriety the - authors of this singular hypothesis invoke the doctrines of mineral - pseudomorphism, as taught by Rose, Blum, Bischof, and Dana. In - replacement pseudomorphs, as understood by these authors, a mineral - species disappears and is replaced by another which retains the - external form of the first. Could it be shown that the calcite of the - cell-wall of Eozoon was once serpentine, this portion of carbonate - of lime would be a replacement pseudomorph after serpentine; but why - the portions of this mineral, which on the hypothesis of Messrs. King - and Rowney have been thus replaced, should assume the forms of a - foraminiferal skeleton, is precisely what our authors fail to show, - and, as all must see, is the gist of the whole matter. - - "Messrs. King and Rowney, it will be observed, assume the existence - of calcite as a replacement pseudomorph after serpentine, but give - no evidence of the possibility of such pseudomorphs. Both Rose and - Bischof regard serpentine itself as in all cases, of pseudomorphous - origin, and as the last result of the changes of a number of mineral - species, but give us no example of the pseudomorphous alteration of - serpentine itself. It is, according to Bischof, the very insolubility - and unalterability of serpentine which cause it to appear as the - final result of the change of so many mineral species. Delesse, - moreover, in his carefully prepared table of pseudomorphous minerals, - in which he has resumed the results of his own and all preceding - observers, does not admit the pseudomorphic replacement of serpentine - by calcite, nor indeed by any other species.[AV] If, then, such - pseudomorphs exist, it appears to be a fact hitherto unobserved, - and our authors should at least have given us some evidence of this - remarkable case of pseudomorphism by which they seek to support their - singular hypothesis. - -[Footnote AV: _Annales des Mines_, 5, xvi., 317.] - - "I hasten to say, however, that I reject with Scheerer, Delesse - and Naumann, a great part of the supposed cases of mineral - pseudomorphism, and do not even admit the pseudomorphous origin of - serpentine itself, but believe that this, with many other related - silicates, has been formed by direct chemical precipitation. This - view, which our authors do me the honour to criticise, was set - forth by me in 1860 and 1861,[AW] and will be found noticed more - in detail in the _Geological Report of Canada_, for 1866, p. 229. - I have there and elsewhere maintained that 'steatite, serpentine, - pyroxene, hornblende, and in many cases garnet, epidote, and other - silicated minerals, are formed by a crystallization and molecular - re-arrangement of silicates, generated by chemical processes in - waters at the earth's surface.'[AX] - -[Footnote AW: _Amer. Journ. Science_ (2), xxix., 284; xxxii., 286.] - -[Footnote AX: _Ibid._, xxxvii., 266; xxxviii., 183.] - - "This view, which at once explains the origin of all these bedded - rocks, and the fact that their constituent mineral species, like - silica and carbonate of lime, replace the perishable matter of - organic forms, is designated by Messrs. King and Rowney 'as so - completely destitute of the characters of a scientific hypothesis - as to be wholly unworthy of consideration,' and they speak of my - attempt to maintain this hypothesis as 'a total collapse.' How far - this statement is from the truth my readers shall judge. My views - as to the origin of serpentine and other silicated minerals were - set forth by me as above in 1860-1864, before anything was known - of the mineralogy of Eozoon, and were forced upon me by my studies - of the older crystalline schists of North America. Naumann had - already pointed out the necessity of some such hypothesis when he - protested against the extravagances of the pseudomorphist school, - and maintained that the beds of various silicates found in the - crystalline schists are original deposits, and not formed by an - epigenic process (_Geognosie_, ii., 65, 154, and _Bull. Soc. Geol. - de France_, 2, xviii., 678). This conclusion of Naumann's I have - attempted to explain and support by numerous facts and observations, - which have led me to the hypothesis in question. Gümbel, who accepts - Naumann's view, sustains my hypothesis of the origin of these rocks - in a most emphatic manner,[AY] and Credner, in discussing the genesis - of the Eozoic rocks, has most ably defended it.[AZ] So much for my - theoretical views so contemptuously denounced by Messrs. King and - Rowney, which are nevertheless unhesitatingly adopted by the two - geologists of the time who have made the most special studies of the - rocks in question,--Gümbel in Germany, and Credner in North America. - -[Footnote AY: _Proc. Royal Bavarian Acad._ for 1866, translated in -_Can. Naturalist_, iii., 81.] - -[Footnote AZ: _Die Gliederung der Eozoischen Formations gruppe -Nord.-Amerikas,--a Thesis defended before the University of Leipzig, -March 15, 1869_, by Dr. Hermann Credner. Halle, 1869, p. 53.] - - "It would be a thankless task to follow Messrs. King and Rowney - through their long paper, which abounds in statements as unsound as - those I have just exposed, but I cannot conclude without calling - attention to one misconception of theirs as to my view of the origin - of limestones. They quote Professor Hull's remark to the effect that - the researches of the Canadian geologists and others have shown that - the oldest known limestones of the world owe their origin to Eozoon, - and remark that the existence of great limestone beds in the Eozoic - rocks seems to have influenced Lyell, Ramsay, and others in admitting - the received view of Eozoon. Were there no other conceivable source - of limestones than Eozoon or similar calcareous skeletons, one might - suppose that the presence of such rocks in the Laurentian system - could have thus influenced these distinguished geologists, but - there are found beneath the Eozoon horizon two great formations of - limestone in which this fossil has never been detected. When found, - indeed, it owes its conservation in a readily recognisable form to - the fact, that it was preserved by the introduction of serpentine - at the time of its growth. Above the unbroken Eozoon reefs are - limestones made up apparently of the debris of Eozoon thus preserved - by serpentine, and there is no doubt that this calcareous rhizopod, - growing in water where serpentine was not in process of formation, - might, and probably did, build up pure limestone beds like those - formed in later times from the ruins of corals and crinoids. Nor - is there anything inconsistent in this with the assertion which - Messrs. King and Rowney quote from me, viz., that the popular notion - that _all limestone formations_ owe their origin to organic life is - based upon a fallacy. The idea that marine organisms originate the - carbonate of lime of their skeletons, in a manner somewhat similar to - that in which plants generate the organic matter of theirs, appears - to be commonly held among certain geologists. It cannot, however, - be too often repeated that animals only appropriate the carbonate - of lime which is furnished them by chemical reaction. Were there - no animals present to make use of it, the carbonate of lime would - accumulate in natural waters till these became saturated, and would - then be deposited in an insoluble form; and although thousands of - feet of limestone have been formed from the calcareous skeletons - of marine animals, it is not less true that great beds of ancient - marble, like many modern travertines and tufas, have been deposited - without the intervention of life, and even in waters from which - living organisms were probably absent. To illustrate this with the - parallel case of silicious deposits, there are great beds made - up of silicious shields of diatoms. These during their lifetime - extracted from the waters the dissolved silica, which, but for their - intervention, might have accumulated till it was at length deposited - in the form of schist or of crystalline quartz. In either case the - function of the coral, the rhizopod, or the diatom is limited to - assimilating the carbonate of lime or the silica from its solution, - and the organised form thus given to these substances is purely - accidental. It is characteristic of our authors, that, rather than - admit the limestone beds of the Eozoon rocks to have been formed like - beds of coralline limestone, or deposited as chemical precipitates - like travertine, they prefer, as they assure us, to regard them as - the results of that hitherto unheard-of process, the pseudomorphism - of serpentine; as if the deposition of the carbonate of lime in - the place of dissolved serpentine were a simpler process than its - direct deposition in one or the other of the ways which all the world - understands!" - - -(C.) Dr. Carpenter on the Foraminiferal Relations of Eozoon. - - In the _Annals of Natural History_, for June, 1874, Dr. Carpenter - has given a crushing reply to some objections raised in that journal - by Mr. Carter. He first shows, contrary to the statement of Mr. - Carter, that the fine nummuline tubulation corresponds precisely in - its direction with reference to the chambers, with that observed in - Nummulites and Orbitoides. In the second place, he shows by clear - descriptions and figures, that the relation of the canal system to - the fine tubulation is precisely that which he had demonstrated in - more recent nummuline and rotaline Foraminifera. In the third place - he adduces additional facts to show that in some specimens of Eozoon - the calcareous skeleton has been filled with calcite before the - introduction of any foreign mineral matter. He concludes the argument - in the following words:-- - - "I have thus shown:--(1) that the 'utter incompatibility' asserted - by my opponents to exist between the arrangement of the supposed - 'nummuline tubulation' of Eozoon and true Nummuline structure, so far - from having any real existence, really furnishes an additional point - of conformity; and (2) that three most striking and complete points - of conformity exist between the structure of the best-preserved - specimens of Eozoon, and that of the Nummulites whose tubulation I - described in 1849, and of the Calcarina whose tubulation and canal - system I described in 1860. - - "That I have not troubled myself to reply to the reiterated arguments - in favour of the doctrine [of mineral origin] advanced by Professors - King and Rowney on the strength of the occurrence of undoubted - results of mineralization in the Canadian Ophite, and of still more - marked evidences of the same action in other Ophites, has been - simply because these arguments appeared to me, as I thought they - must also appear to others, entirely destitute of logical force. - Every scientific palæontologist I have ever been acquainted with has - taken the _best_ preserved specimens, not the _worst_, as the basis - of his reconstructions; and if he should meet with distinct evidence - of characteristic organic structure in even a very small fragment - of a doubtful form, he would consider the organic origin of that - form to be thereby substantiated, whatever might be the evidence of - purely mineral arrangement which the greater part of his specimen - may present,--since he would regard that arrangement as a probable - result of _subsequent_ mineralization, by which the original organic - structure has been more or less obscured. If this is _not_ to be our - rule of interpretation, a large part of the palæontological work - of our time must be thrown aside as worthless. If, for example, - Professors King and Rowney were to begin their study of Nummulites - by the examination of their most mineralized forms, they would deem - themselves justified (according to their canons of interpretation) - in denying the existence of the tubulation and canalization which I - described (in 1849) in the N. lævigata preserved almost unaltered in - the London Clay of Bracklesham Bay. - - "My own notions of Eozoic structure have been formed on the - examination of the Canadian specimens selected by the experienced - discrimination of Sir William Logan, as those in which there was - _least_ appearance of metamorphism; and having found in these what I - regarded as unmistakable evidence of an organic structure conformable - to the foraminiferal type, I cannot regard it as any disproof of - that conformity, either to show that the true Eozoic structure has - been frequently altered by mineral metamorphism, or to adduce the - occurrence of Ophites more or less resembling the Eozoon of the - Canadian Laurentians at various subsequent geological epochs. The - existence of any number or variety of _purely mineral_ Ophites would - not disprove the organic origin of the Canadian Eozoon--unless - it could be shown that some wonderful process of mineralization - is competent to construct not only its multiplied alternating - lamellæ of calcite and serpentine, the dendritic extensions of the - latter into the former, and the 'acicular layer' of decalcified - specimens, but (1) the _pre-existing canalization_ of the calcareous - lamellæ, (2) the _unfilled nummuline tubulation_ of the proper - wall of the chambers, and (3) the peculiar _calcarine_ relation of - the canalization and tubulation, here described and figured from - specimens in the highest state of preservation, showing the _least_ - evidence of any mineral change. - - "On the other hand, Professors King and Rowney began their studies of - Eozoic structure upon the Galway Ophite--a rock which Sir Roderick - Murchison described to me at the time as having been so much 'tumbled - about,' that he was not at all sure of its geological position, and - which exhibits such obvious evidences of mineralization, with such - an entire absence of any vestige of organic structure, that I should - never for a moment have thought of crediting it with an organic - origin, but for the general resemblance of its serpentine-grains - to those of the 'acervuline' portion of the Canadian Eozoon. They - pronounced with the most positive certainty upon the mineral origin - of the Canadian Eozoon, before they had subjected transparent - sections of it to any of that careful comparison with similar - sections of recent Foraminifera, which had been the basis of - Dr. Dawson's original determination, and of my own subsequent - confirmation, of its organic structure. - -[Illustration: - Plate VIII. - - _Eozoon and Chrysotile Veins, etc._ - - Fig. 1.--Portion of two laminæ and intervening serpentine, - with chrysotile vein. (_a._) Proper wall tubulated. (_b._) - Intermediate skeleton, with large canals. (_c._) Openings of - small chamberlets filled with serpentine. (_s._) Serpentine - filling chamber. (_s^1._) Vein of chrysotile, showing its - difference from the proper wall. - - Fig. 2.--Junction of a canal and the proper wall. Lettering as in - Fig. 1. - - Fig. 3.--Proper wall shifted by a fault, and more recent chrysotile - vein not faulted. Lettering as in Fig. 1. - - Fig. 4.--Large and small canals filled with dolomite. - - Fig. 5.--Abnormally thick portion of intermediate skeleton, with - large tubes and small canals filled with dolomite.] - - - - -CHAPTER VIII. - -THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. - - -The thoughts suggested to the philosophical naturalist by the -contemplation of the dawn of life on our planet are necessarily many -and exciting, and the subject has in it the materials for enabling the -general reader better to judge of some of the theories of the origin of -life agitated in our time. In this respect our dawn-animal has scarcely -yet had justice; and we may not be able to render this in these pages. -Let us put it into the witness-box, however, and try to elicit its -testimony as to the beginnings of life. - -Looking down from the elevation of our physiological and mental -superiority, it is difficult to realize the exact conditions in which -life exists in creatures so simple as the Protozoa. There may perhaps -be higher intelligences that find it equally difficult to realize how -life and reason can manifest themselves in such poor houses of clay -as those we inhabit. But placing ourselves near to these creatures, -and entering as it were into sympathy with them, we can understand -something of their powers and feelings. In the first place it is plain -that they can vigorously, if roughly, exercise those mechanical, -chemical, and vegetative powers of life which are characteristic of -the animal. They can seize, swallow, digest, and assimilate food; and, -employing its albuminous parts in nourishing their tissues, can burn -away the rest in processes akin to our respiration, or reject it from -their system. Like us, they can subsist only on food which the plant -has previously produced; for in this world, from the beginning of time, -the plant has been the only organism which could use the solar light -and heat as forces to enable it to turn the dead elements of matter -into living, growing tissues, and into organic compounds capable of -nourishing the animal. Like us, the Protozoa expend the food which -they have assimilated in the production of animal force, and in doing -so cause it to be oxidized, or burnt away, and resolved again into -dead matter. It is true that we have much more complicated apparatus -for performing these functions, but it does not follow that this gives -us much real superiority, except relatively to the more difficult -conditions of our existence. The gourmand who enjoys his dinner may -have no more pleasure in the act than the Amœba which swallows a -Diatom; and for all that the man knows of the subsequent processes to -which the food is subjected, his interior might be a mass of jelly, -with extemporised vacuoles, like that of his humble fellow-animal. The -workman or the athlete has bones and muscles of vastly complicated -structure, but to him the muscular act is as simple and unconscious a -process as the sending out of a pseudopod to a Protozoon. The clay is -after all the same, and there may be as much credit to the artist in -making a simple organism with varied powers, as a more complex frame -for doing nicer work. It is a weakness of humanity to plume itself on -advantages not of its own making, and to treat its superior gifts as -if they were the result of its own endeavours. The truculent traveller -who illustrated his boast of superiority over the Indian by comparing -his rifle with the bow and arrows of the savage, was well answered by -the question, "Can you make a rifle?" and when he had to answer, "No," -by the rejoinder, "Then I am at least better than you, for I can make -my bow and arrows." The Amœba or the Eozoon is probably no more than we -its own creator; but if it could produce itself out of vegetable matter -or out of inorganic substances, it might claim in so far a higher -place in the scale of being than we; and as it is, it can assert equal -powers of digestion, assimilation, and motion, with much less of bodily -mechanism. - -In order that we may feel, a complicated apparatus of nerves and -brain-cells has to be constructed and set to work; but the Protozoon, -without any distinct brain, is all brain, and its sensation is simply -direct. Thus vision in these creatures is probably performed in a rough -way by any part of their transparent bodies, and taste and smell are no -doubt in the same case. Whether they have any perception of sound as -distinct from the mere vibrations ascertained by touch, we do not know. -Here also we are not far removed above the Protozoa, especially those -of us to whom touch, seeing, and hearing are mere feelings, without -thought or knowledge of the apparatus employed. We might so far as -well be Amœbas. As we rise higher we meet with more differences. Yet -it is evident that our gelatinous fellow-being can feel pain, dread -danger, desire possessions, enjoy pleasure, and in a simple unconscious -way entertain many of the appetites and passions that affect ourselves. -The wonder is that with so little of organization it can do so much. -Yet, perhaps, life can manifest itself in a broader and more intense -way where there is little organization; and a highly strung and -complex organism is not so much a necessary condition of a higher life -as a mere means of better adapting it to its present surroundings. -Those philosophies which identify the thinking mind with the material -organism, must seem outrageous blunders to an Amœba on the one hand, or -to an angel on the other, could either be enabled to understand them; -which, however, is not very probable, as they are too intimately bound -up with the mere prejudices incident to the present condition of our -humanity. In any case the Protozoa teach us how much of animal function -may be fulfilled by a very simple organism, and warn us against the -fallacy that creatures of this simple structure are necessarily nearer -to inorganic matter, and more easily developed from it than beings of -more complex mould. - -A similar lesson is taught by the complexity of their skeletons. -We speak in a crude unscientific way of these animals accumulating -calcareous matter, and building up reefs of limestone. We must, -however, bear in mind that they are as dependent on their food for -the materials of their skeletons as we are, and that their crusts -grow in the interior of the sarcode just as our bones do within our -bodies. The provision even for nourishing the interior of the skeleton -by tubuli and canals is in principle similar to that involved in the -Haversian canals, cells, and canalicules of bone. The Amœba of course -knows neither more nor less of this than the average Englishman. -It is altogether a matter of unconscious growth. The process in -the Protozoa strikes some minds, however, as the more wonderful of -the two. It is, says an eminent modern physiologist, a matter of -"profound significance" that this "particle of jelly [the sarcode -of a Foraminifer] is capable of guiding physical forces in such a -manner as to give rise to these exquisite and almost mathematically -arranged structures." Respecting the structures themselves there is no -exaggeration in this. No arch or dome framed by human skill is more -perfect in beauty or in the realization of mechanical ideas than the -tests of some Foraminifera, and none is so complete and wonderful in -its internal structure. The particle of jelly, however, is a figure of -speech. The body of the humblest Foraminifer is much more than this. -It is an organism with divers parts, as we have already seen in a -previous chapter, and it is endowed with the mysterious forces of life -which in it guide the physical forces, just as they do in building -up phosphate of lime in our bones, or indeed just as the will of the -architect does in building a palace. The profound significance which -this has, reaches beyond the domain of the physical and vital, even to -the spiritual. It clings to all our conceptions of living things: quite -as much, for example, to the evolution of an animal with all its parts -from a one-celled germ, or to the connection of brain-cells with the -manifestations of intelligence. Viewed in this way, we may share with -the author of the sentence I have quoted his feeling of veneration in -the presence of this great wonder of animal life, "burning, and not -consumed," nay, building up, and that in many and beautiful forms. We -may realize it most of all in the presence of the organism which was -perhaps the first to manifest on our planet these marvellous powers. -We must, however, here also, beware of that credulity which makes too -many thinkers limit their conceptions altogether to physical force -in matters of this kind. The merely materialistic physiologist is -really in no better position than the savage who quails before the -thunderstorm, or rejoices in the solar warmth, and seeing no force or -power beyond, fancies himself in the immediate presence of his God. In -Eozoon we must discern not only a mass of jelly, but a being endowed -with that higher vital force which surpasses vegetable life and also -physical and chemical forces; and in this animal energy we must see an -emanation from a Will higher than our own, ruling vitality itself; and -this not merely to the end of constructing the skeleton of a Protozoon, -but of elaborating all the wonderful developments of life that were to -follow in succeeding ages, and with reference to which the production -and growth of this creature were initial steps. It is this mystery of -design which really constitutes the "profound significance" of the -foraminiferal skeleton. - -Another phenomenon of animality forced upon our notice by the Protozoa -is that of the conditions of life in animals not individual, as we -are, but aggregative and cumulative in indefinite masses. What, for -instance, the relations to each other of the Polyps, growing together -in a coral mass, of the separate parts of a Sponge, or the separate -cells of a Foraminifer, or of the sarcode mass of an indefinitely -spread out Stromatopora or Bathybius. In the case of the Polyps, we -may believe that there is special sensation in the tentacles and -oral opening of each individual, and that each may experience hunger -when in want, or satisfaction when it is filled with food, and that -injuries to one part of the mass may indirectly affect other parts, -but that the nutrition of the whole mass may be as much unfelt by the -individual Polyps as the processes going on in our own bones are by -us. So in the case of a large Sponge or Foraminifer, there may be some -special sensation in individual cells, pseudopods, or segments, and -the general sensation may be very limited, while unconscious living -powers pervade the whole. In this matter of aggregation of animals we -have thus various grades. The Foraminifers and Sponges present us with -the simplest of all, and that which most resembles the aggregation of -buds in the plant. The Polyps and complex Bryozoons present a higher -and more specialised type; and though the bilateral symmetry which -obtains in the higher animals is of a different nature, it still at -least reminds us of that multiplication of similar parts which we see -in the lower grades of being. It is worthy of notice here that the -lower animals which show aggregative tendencies present but imperfect -indications, or none at all, of bilateral symmetry. Their bodies, like -those of plants, are for the most part built up around a central axis, -or they show tendencies to spiral modes of growth. - -It is this composite sort of life which is connected with the main -geological function of the Foraminifer. While active sensation, -appetite, and enjoyment pervade the pseudopods and external sarcode -of the mass, the hard skeleton common to the whole is growing within; -and in this way the calcareous matter is gradually removed from -the sea water, and built up in solid reefs, or in piles of loose -foraminiferal shells. Thus it is the aggregative or common life, -alike in Foraminifers as in Corals, that tends most powerfully to the -accumulation of calcareous matter; and those creatures whose life is -of this complex character are best suited to be world-builders, since -the result of their growth is not merely a cemetery of their osseous -remains, but a huge communistic edifice, to which multitudes of lives -have contributed, and in which successive generations take up their -abode on the remains of their ancestors. This process, so potent in -the progress of the earth's geological history, began, as far as we -know, with Eozoon. - -Whether, then, in questioning our proto-foraminifer, we have reference -to the vital functions of its gelatinous sarcode, to the complexity and -beauty of its calcareous test, or to its capacity for effecting great -material results through the union of individuals, we perceive that we -have to do, not with a low condition of those powers which we designate -life, but with the manifestation of those powers through the means of a -simple organism; and this in a degree of perfection which we, from our -point of view, would have in the first instance supposed impossible. - -If we imagine a world altogether destitute of life, we still might -have geological formations in progress. Not only would volcanoes belch -forth their liquid lavas and their stones and ashes, but the waves and -currents of the ocean and the rains and streams on the land, with the -ceaseless decomposing action of the carbonic acid of the atmosphere, -would be piling up mud, sand, and pebbles in the sea. There might even -be some formation of limestone taking place where springs charged -with bicarbonate of lime were oozing out on the land or the bottom of -the waters. But in such a world all the carbon would be in the state -of carbonic acid, and all the limestone would either be diffused in -small quantities through various rocks or in limited local beds, or -in solution, perhaps as chloride of calcium, in the sea. Dr. Hunt has -given chemical grounds for supposing that the most ancient seas were -largely supplied with this very soluble salt, instead of the chloride -of sodium, or common salt, which now prevails in the sea-water. - -Where in such a world would life be introduced? on the land or in the -waters? All scientific probability would say in the latter. The ocean -is now vastly more populous than the land. The waters alone afford -the conditions necessary at once for the most minute and the grandest -organisms, at once for the simplest and for others of the most complex -character. Especially do they afford the best conditions for those -animals which subsist in complex communities, and which aggregate large -quantities of mineral matter in their skeletons. So true is this that -up to the present time all the species of Protozoa and of the animals -most nearly allied to them are aquatic. Even in the waters, however, -plant life, though possibly in very simple forms, must precede the -animal. - -Let humble plants, then, be introduced in the waters, and they would -at once begin to use the solar light for the purpose of decomposing -carbonic acid, and forming carbon compounds which had not before -existed, and which independently of vegetable life would never have -existed. At the same time lime and other mineral substances present in -the sea-water would be fixed in the tissues of these plants, either in -a minute state of division, as little grains or Coccoliths, or in more -solid masses like those of the Corallines and Nullipores. In this way -a beginning of limestone formation might be made, and quantities of -carbonaceous and bituminous matter, resulting from the decay of marine -plants might accumulate in the sea-bottom. Now arises the opportunity -for animal life. The plants have collected stores of organic matter, -and their minute germs, along with microscopic species, are floating -everywhere in the sea. Nay, there may be abundant examples of those -Amœba-like germs of aquatic plants, simulating for a time the life -of the animal, and then returning into the circle of vegetable life. -In these some might see precursors of the Protozoa, though they are -probably rather prophetic analogues than blood relations. The plant -has fulfilled its function as far as the waters are concerned, and now -arises the opportunity for the animal. In what form shall it appear? -Many of its higher forms, those which depend upon animal food or on the -more complex plants for subsistence, would obviously be unsuitable. -Further, the sea-water is still too much saturated with saline matter -to be fit for the higher animals of the waters. Still further, there -may be a residue of internal heat forbidding coolness, and that -solution of free oxygen which is an essential condition of existence to -most of the modern animals. Something must be found suitable for this -saline, imperfectly oxygenated, tepid sea. Something too is wanted that -can aid in introducing conditions more favourable to higher life in -the future. Our experience of the modern world shows us that all these -conditions can be better fulfilled by the Protozoa than by any other -creatures. They can live now equally in those great depths of ocean -where the conditions are most unfavourable to other forms of life, and -in tepid unhealthy pools overstocked with vegetable matter in a state -of putridity. They form a most suitable basis for higher forms of life. -They have remarkable powers of removing mineral matters from the waters -and of fixing them in solid forms. So in the fitness of things Eozoon -is just what we need, and after it has spread itself over the mud and -rock of the primeval seas, and built up extensive reefs therein, other -animals may be introduced capable of feeding on it, or of sheltering -themselves in its stony masses, and thus we have the appropriate dawn -of animal life. - -But what are we to say of the cause of this new series of facts, so -wonderfully superimposed upon the merely vegetable and mineral? Must -it remain to us as an act of creation, or was it derived from some -pre-existing matter in which it had been potentially present? Science -fails to inform us, but conjectural "phylogeny" steps in and takes its -place. Haeckel, the prophet of this new philosophy, waves his magic -wand, and simple masses of sarcode spring from inorganic matter, and -form diffused sheets of sea-slime, from which are in time separated -distinct Amœboid and Foraminiferal forms. Experience, however, gives us -no facts whereon to build this supposition, and it remains neither more -nor less scientific or certain than that old fancy of the Egyptians, -which derived animals from the fertile mud of the Nile. - -If we fail to learn anything of the origin of Eozoon, and if its -life-processes are just as inscrutable as those of higher creatures, -we can at least inquire as to its history in geological time. In this -respect we find in the first place that the Protozoa have not had -a monopoly in their profession of accumulators of calcareous rock. -Originated by Eozoon in the old Laurentian time, this process has -been proceeding throughout the geological ages; and while Protozoa, -equally simple with the great prototype of the race, have been and -are continuing its function, and producing new limestones in every -geological period, and so adding to the volume of the successive -formations, new workers of higher grades have been introduced, capable -of enjoying higher forms of animal activity, and equally of labouring -at the great task of continent-building; of existing, too, in seas -less rich in mineral substances than those of the Eozoic time, and for -that very reason better suited to higher and more skilled artists. It -is to be observed in connection with this, that as the work of the -Foraminifers has thus been assumed by others, their size and importance -have diminished, and the grander forms of more recent times have some -of them been fain to build up their hard parts of cemented sand instead -of limestone. - -But we further find that, while the first though not the only organic -gatherers of limestone from the ocean waters, they have had to do, not -merely with the formation of calcareous sediments, but also with that -of silicious deposits. The greenish silicate called glauconite, or -green-sand, is found to be associated with much of the foraminiferal -slime now accumulating in the ocean, and also with the older deposits -of this kind now consolidated in chalks and similar rocks. This name -glauconite is, as Dr. Hunt has shown, employed to designate not only -the hydrous silicate of iron and potash, which perhaps has the best -right to it, but also compounds which contain in addition large -percentages of alumina, or magnesia, or both; and one glauconite from -the Tertiary limestones near Paris, is said to be a true serpentine, -or hydrous silicate of magnesia.[BA] Now the association of such -substances with Foraminifera is not purely accidental. Just as a -fragment of decaying wood, imbedded in sediment, has the power of -decomposing soluble silicates carried to it by water, and parting with -its carbon in the form of carbonic acid, in exchange for the silica, -and thus replacing, particle by particle, the carbon of the wood -with silicon, so that at length it becomes petrified into a flinty -mass, so the sarcode of a Foraminifer, which is a more dense kind of -animal matter than is usually supposed, can in like manner abstract -silica from the surrounding water or water-soaked sediment. From some -peculiarity in the conditions of the case, however, our Protozoon -usually becomes petrified with a hydrous silicate instead of with pure -silica. The favourable conditions presented by the deep sea for the -combination of silica with bases, may perhaps account in part for -this. But whatever the cause, it is usual to find fossil Foraminifera -with their sarcode replaced by such material. We also find beds of -glauconite retaining the forms of Foraminifera, while the calcareous -tests of these have been removed, apparently by acid waters. - -[Footnote BA: Berthier, quoted by Hunt.] - -One consideration which, though conjectural, deserves notice, is -connected with the food of these humble animals. They are known to feed -to a large extent on minute plants, the Diatoms, and other organisms -having silica in their skeletons or cell-walls, and consequently -soluble silicates in their juices. The silicious matter contained -in these organisms is not wanted by the Foraminifera for their own -skeletons, and will therefore be voided by them as an excrementitious -matter. In this way, where Foraminifera greatly abound, there may be a -large production of soluble silica and silicates, in a condition ready -to enter into new and insoluble compounds, and to fill the cavities -and pores of dead shells. Thus glauconite and even serpentine may, -in a certain sense, be a sort of foraminiferal coprolitic matter or -excrement. Of course it is not necessary to suppose that this is the -only source of such materials. They may be formed in other ways; but I -suggest this as at least a possible link of connection. - -Whether or not the conjecture last mentioned has any validity, there -is another and most curious bond of connection between oceanic -Protozoa and silicious deposits. Professor Wyville Thompson reports -from the _Challenger_ soundings, that in certain areas of the South -Pacific the ordinary foraminiferal ooze is replaced by a peculiar red -clay, which he attributes to the action of water laden with carbonic -acid, in removing all the lime, and leaving this red mud as a sort -of ash, composed of silica, alumina, and iron oxide. Now this is in -all probability a product of the decomposition and oxidation of the -glauconitic matter contained in the ooze. Thus we learn that when areas -on which calcareous deposits have been accumulated by Protozoa, are -invaded by cold arctic or antarctic waters charged with carbonic acid, -the carbonate of lime may be removed, and the glauconite left, or even -the latter may be decomposed, leaving silicious, aluminous, and other -deposits, which may be quite destitute of any organic structures, or -retain only such remnants of them as have been accidentally or by -their more resisting character protected from destruction.[BB] In this -way it may be possible that many silicious rocks of the Laurentian -and Primordial ages, which now show no trace of organization, may be -indirectly products of the action of life. When the recent deposits -discovered by the _Challenger_ dredgings shall have been more fully -examined, we may perhaps have the means of distinguishing such rocks, -and thus of still further enlarging our conceptions of the part played -by Protozoa in the drama of the earth's history. In any case it seems -plain that beds of green-sand and similar hydrous silicates may be the -residue of thick deposits of foraminiferal limestone or chalky matter, -and that these silicates may in their turn be oxidised and decomposed, -leaving beds of apparently inorganic clay. Such beds may finally be -consolidated and rendered crystalline by metamorphism, and thus a -great variety of silicated rocks may result, retaining little or no -indication of any connection with the agency of life. We can scarcely -yet conjecture the amount of light which these new facts may eventually -throw on the serpentine and other rocks of the Eozoic age. In the -meantime they open up a noble field to chemists and microscopists. - -[Footnote BB: The "red chalk" of Antrim, and that of Speeton, contain -arenaceous Foraminifera and silicious casts of their shells, apparently -different from typical glauconite, and the extremely fine ferruginous -and argillaceous sediment of these chalks may well be decomposed -glauconitic matter like that of the South Pacific. I have found these -beds, the hard limestones of the French Neocomian, and the altered -green-sands of the Alps, very instructive for comparison with the -Laurentian limestones; and they well deserve study by all interested in -such subjects.] - -When the marvellous results of recent deep-sea dredgings were first -made known, and it was found that chalky foraminiferal earth is yet -accumulating in the Atlantic, with sponges and sea urchins resembling -in many respects those whose remains exist in the chalk, the fact was -expressed by the statement that we still live in the chalk period. Thus -stated the conclusion is scarcely correct. We do not live in the chalk -period, but the conditions of the chalk period still exist in the -deep sea. We may say more than this. To some extent the conditions of -the Laurentian period still exist in the sea, except in so far as they -have been removed by the action of the Foraminifera and other limestone -builders. To those who can realize the enormous lapse of time involved -in the geological history of the earth, this conveys an impression -almost of eternity in the existence of this oldest of all the families -of the animal kingdom. - -We are still more deeply impressed with this when we bring into view -the great physical changes which have occurred since the dawn of life. -When we consider that the skeletons of Eozoon contribute to form the -oldest hills of our continents; that they have been sealed up in solid -marble, and that they are associated with hard crystalline rocks -contorted in the most fantastic manner; that these rocks have almost -from the beginning of geological time been undergoing waste to supply -the material of new formations; that they have witnessed innumerable -subsidences and elevations of the continents; and that the greatest -mountain chains of the earth have been built up from the sea since -Eozoon began to exist,--we acquire a most profound impression of the -persistence of the lower forms of animal life, and know that mountains -may be removed and continents swept away and replaced, before the least -of the humble gelatinous Protozoa can finally perish. Life may be a -fleeting thing in the individual, but as handed down through successive -generations of beings, and as a constant animating power in successive -organisms, it appears, like its Creator, eternal. - -This leads to another and very serious question. How long did lineal -descendants of Eozoon exist, and do they still exist? We may for the -present consider this question apart from ideas of derivation and -elevation into higher planes of existence. Eozoon as a species and -even as a genus may cease to exist with the Eozoic age, and we have no -evidence whatever that Archæocyathus, Stromatopora, or Receptaculites -are its modified descendants. As far as their structures inform us, -they may as much claim to be original creations as Eozoon itself. -Still descendants of Eozoon may have continued to exist, though we -have not yet met with them. I should not be surprised to hear of a -veritable specimen being some day dredged alive in the Atlantic or -the Pacific. It is also to be observed that in animals so simple as -Eozoon many varieties may appear, widely different from the original. -In these the general form and habit of life are the most likely things -to change, the minute structures much less so. We need not, therefore, -be surprised to find its descendants diminishing in size or altering -in general form, while the characters of the fine tubulation and of -the canal system would remain. We need not wonder if any sessile -Foraminifer of the Nummuline group should prove to be a descendant -of Eozoon. It would be less likely that a Sponge or a Foraminifer of -the Rotaline type should originate from it. If one could only secure -a succession of deep-sea limestones with Foraminifers, extending all -the way from the Laurentian to the present time, I can imagine nothing -more interesting than to compare the whole series, with the view of -ascertaining the limits of descent with variation, and the points where -new forms are introduced. We have not yet such a series, but it may be -obtained; and as Foraminifera are eminently cosmopolitan, occurring -over vastly wide areas of sea-bottom, and are very variable, they would -afford a better test of theories of derivation than any that can be -obtained from the more locally distributed and less variable animals -of higher grade. I was much struck with this recently, in examining a -series of Foraminifera from the Cretaceous of Manitoba, and comparing -them with the varietal forms of the same species in the interior of -Nebraska, 500 miles to the south, and with those of the English chalk -and of the modern seas. In all these different times and places we had -the same species. In all they existed under so many varietal forms -passing into each other, that in former times every species had been -multiplied into several. Yet in all, the identical varietal forms -were repeated with the most minute markings alike. Here were at once -constancy the most remarkable and variations the most extensive. If we -dwell on the one to the exclusion of the other, we reach only one-sided -conclusions, imperfect and unsatisfactory. By taking both in connection -we can alone realize the full significance of the facts. We cannot -yet obtain such series for all geological time; but it may even now -be worth while to inquire, What do we know as to any modification in -the case of the primeval Foraminifers, whether with reference to the -derivation from them of other Protozoa or of higher forms of life? - -There is no link whatever in geological fact to connect Eozoon with any -of the Mollusks, Radiates, or Crustaceans of the succeeding Primordial. -What may be discovered in the future we cannot conjecture; but at -present these stand before us as distinct creations. It would of course -be more probable that Eozoon should be the ancestor of some of the -Foraminifera of the Primordial age, but strangely enough it is very -dissimilar from all these except Stromatopora; and here, as already -stated, the evidence of minute structure fails to a great extent, and -Eozoon Bavaricum of the Huronian age scarcely helps to bridge over the -gap which yawns in our imperfect geological record. Of actual facts, -therefore, we have none; and those evolutionists who have regarded the -dawn-animal as an evidence in their favour, have been obliged to have -recourse to supposition and assumption. - -Taking the ground of the derivationist, it is convenient to assume -(1) that Eozoon was either the first or nearly the first of animals, -and that, being a Protozoan of simple structure, it constitutes an -appropriate beginning of life; (2) that it originated from some -unexplained change in the protoplasmic or albuminous matter of some -humble plant, or directly from inorganic matter, or at least was -descended from some creature only a little more simple which had -being in this way; (3) that it had in itself unlimited capacities -for variation and also for extension in time; (4) that it tended to -multiply rapidly, and at last so to occupy the ocean that a struggle -for existence arose; (5) that though at first, from the very nature -of its origin, adapted to the conditions of the world, yet as these -conditions became altered by physical changes, it was induced to -accommodate itself to them, and so to pass into new species and genera, -until at last it appeared in entirely new types in the Primordial fauna. - -These assumptions are, with the exception of the first two, merely -the application to Eozoon of what have been called the Darwinian laws -of multiplication, of limited population, of variation, of change of -physical conditions, and of equilibrium of nature. If otherwise proved, -and shown to be applicable to creatures like Eozoon, of course we must -apply them to it; but in so far as that creature itself is concerned -they are incapable of proof, and some of them contrary to such evidence -as we have. We have, for example, no connecting link between Eozoon and -any form of vegetable life. Its structures are such as to enable us at -once to assign it to the animal kingdom, and if we seek for connecting -links between the lower animals and plants we have to look for them -in the modern waters. We have no reason to conclude that Eozoon could -multiply so rapidly as to fill all the stations suitable for it, and to -commence a struggle for existence. On the contrary, after the lapse of -untold ages the conditions for the life of Foraminifers still exist -over two-thirds of the surface of the earth. In regard to variation, we -have, it is true, evidence of the wide range of varieties of species -in Protozoa, within the limits of the group, but none whatever of any -tendency to pass into other groups. Nor can it be proved that the -conditions of the ocean were so different in Cambrian or Silurian times -as to preclude the continued and comfortable existence of Eozoon. -New creatures came in which superseded it, and new conditions more -favourable in proportion to these new creatures, but neither the new -creatures nor the new conditions were necessarily or probably connected -with Eozoon, any farther than that it may have served newer tribes of -animals for food, and may have rid the sea of some of its superfluous -lime in their interest. In short, the hypothesis of evolution will -explain the derivation of other animals from Eozoon if we adopt its -assumptions, just as it will in that case explain anything else, but -the assumptions are improbable, and contrary to such facts as we know. - -Eozoon itself, however, bears some negative though damaging testimony -against evolution, and its argument may be thus stated in what we may -imagine to be its own expressions:--"I, Eozoon Canadense, being a -creature of low organization and intelligence, and of practical turn, -am no theorist, but have a lively appreciation of such facts as I am -able to perceive. I found myself growing upon the sea-bottom, and know -not whence I came. I grew and flourished for ages, and found no let or -hindrance to my expansion, and abundance of food was always floated -to me without my having to go in search of it. At length a change -came. Certain creatures with hard snouts and jaws began to prey on -me. Whence they came I know not; I cannot think that they came from -the germs which I had dispersed so abundantly throughout the ocean. -Unfortunately, just at the same time lime became a little less abundant -in the waters, perhaps because of the great demands I myself had made, -and thus it was not so easy as before to produce a thick supplemental -skeleton for defence. So I had to give way. I have done my best to -avoid extinction; but it is clear that I must at length be overcome, -and must either disappear or subside into a humbler condition, and that -other creatures better provided for the new conditions of the world -must take my place." In such terms we may suppose that this patriarch -of the seas might tell his history, and mourn his destiny, though he -might also congratulate himself on having in an honest way done his -duty and fulfilled his function in the world, leaving it to other and -perhaps wiser creatures to dispute as to his origin and fate, while -much less perfectly fulfilling the ends of their own existence. - -Thus our dawn-animal has positively no story to tell as to his own -introduction or his transmutation into other forms of existence. -He leaves the mystery of creation where it was; but in connection -with the subsequent history of life we can learn from him a little -as to the laws which have governed the succession of animals in -geological time. First, we may learn that the plan of creation has been -progressive, that there has been an advance from the few, low, and -generalized types of the primæval ocean to the more numerous, higher, -and more specialized types of more recent times. Secondly, we learn -that the lower types, when first introduced, and before they were -subordinated to higher forms of life, existed in some of their grandest -modifications as to form and complexity, and that in succeeding ages, -when higher types were replacing them, they were subjected to decay and -degeneracy. Thirdly, we learn that while the species has a limited term -of existence in geological time, any grand type of animal existence, -like that of the Foraminifera or Sponges, for example, once introduced, -continues and finds throughout all the vicissitudes of the earth some -appropriate residence. Fourthly, as to the mode of introduction of new -types, or whether such creatures as Eozoon had any direct connection -with the subsequent introduction of mollusks, worms, or crustaceans, it -is altogether silent, nor can it predict anything as to the order or -manner of their introduction. - -Had we been permitted to visit the Laurentian seas, and to study Eozoon -and its contemporary Protozoa when alive, it is plain that we could not -have foreseen or predicted from the consideration of such organisms -the future development of life. No amount of study of the prototypal -Foraminifer could have led us distinctly to the conception of even -a Sponge or a Polyp, much less of any of the higher animals. Why is -this? The answer is that the improvement into such higher types does -not take place by any change of the elementary sarcode, either in those -chemical, mechanical, or vital properties which we can study, but in -the adding to it of new structures. In the Sponge, which is perhaps -the nearest type of all, we have the movable pulsating cilium and true -animal cellular tissue, and along with this the spicular or fibrous -skeleton, these structures leading to an entire change in the mode of -life and subsistence. In the higher types of animals it is the same. -Even in the highest we have white blood-corpuscles and germinal matter, -which, in so far as we know, carry on no higher forms of life than -those of an Amœba; but they are now made subordinate to other kinds of -tissue, of great variety and complexity, which never have been observed -to arise out of the growth of any Protozoon. There would be only a very -few conceivable inferences which the highest finite intelligence could -deduce as to the development of future and higher animals. He might -infer that the foraminiferal sarcode, once introduced, might be the -substratum or foundation of other but unknown tissues in the higher -animals, and that the Protozoan type might continue to subsist side -by side with higher forms of living things as they were successively -introduced. He might also infer that the elevation of the animal -kingdom would take place with reference to those new properties of -sensation and voluntary motion in which the humblest animals diverge -from the life of the plant. - -It is important that these points should be clearly before our minds, -because there has been current of late among naturalists a loose way -of writing with reference to them, which seems to have imposed on many -who are not naturalists. It has been said, for example, that such an -organism as Eozoon may include potentially all the structures and -functions of the higher animals, and that it is possible that we might -be able to infer or calculate all these with as much certainty as we -can calculate an eclipse or any other physical phenomenon. Now, there -is not only no foundation in fact for these assertions, but it is from -our present standpoint not conceivable that they can ever be realized. -The laws of inorganic matter give no data whence any _à priori_ -deductions or calculations could be made as to the structure and -vital forces of the plant. The plant gives no data from which we can -calculate the functions of the animal. The Protozoon gives no data from -which we can calculate the specialties of the Mollusc, the Articulate, -or the Vertebrate. Nor unhappily do the present conditions of life of -themselves give us any sure grounds for predicting the new creations -that may be in store for our old planet. Those who think to build a -philosophy and even a religion on such data are mere dreamers, and have -no scientific basis for their dogmas. They are more blind guides than -our primæval Protozoon himself would be, in matters whose real solution -lies in the harmony of our own higher and immaterial nature with the -Being who is the author of all life--the Father "from whom every -family in heaven and earth is named." - -While this work was going through the press, Lyell, the greatest -geological thinker of our time, passed away. In the preceding pages I -have refrained from quoting the many able geologists and biologists who -have publicly accepted the evidence of the animal nature of Eozoon as -sufficient, preferring to rest my case on its own merits rather than on -authority; but it is due to the great man whose loss we now mourn, to -say that, before the discovery of Eozoon, he had expressed on general -grounds his anticipation that fossils would be found in the rocks older -than the so-called Primordial Series, and that he at once admitted the -organic nature of Eozoon, and introduced it, as a fossil, into the -edition of his Elements of Geology published in the same year in which -it was described. - - - - -APPENDIX. - -CHARACTERS OF LAURENTIAN AND HURONIAN PROTOZOA. - - -It may be useful to students to state the technical characters of -Eozoon, in addition to the more popular and general descriptions in the -preceding pages. - - -_Genus_ EOZOON. - -Foraminiferal skeletons, with irregular and often confluent cells, -arranged in concentric and horizontal laminæ, or sometimes piled in an -acervuline manner. Septal orifices irregularly disposed. Proper wall -finely tubulated. Intermediate skeleton with branching canals. - - -Eozoon Canadense, _Dawson_. - -In rounded masses or thick encrusting sheets, frequently of large -dimensions. Typical structure stromatoporoid, or with concentric -calcareous walls, frequently uniting with each other, and separating -flat chambers, more or less mammillated, and spreading into horizontal -lobes and small chamberlets; chambers often confluent and crossed by -irregular calcareous pillars connecting the opposite walls. Upper -part often composed of acervuline chambers of rounded forms. Proper -wall tubulated very finely. Intermediate skeleton largely developed, -especially at the lower part, and traversed by large canals, often -with smaller canals in their interstices. Lower laminæ and chambers -often three millimetres in thickness. Upper laminæ and chambers one -millimetre or less. Age Laurentian and perhaps Huronian. - -_Var._ MINOR.--Supplemental skeleton wanting, except near the base, and -with very fine canals. Laminæ of sarcode much mammillated, thin, and -separated by very thin walls. Probably a depauperated variety. - -_Var._ ACERVULINA.--In oval or rounded masses, wholly acervuline. Cells -rounded; intermediate skeleton absent or much reduced; cell-walls -tubulated. This may be a distinct species, but it closely resembles the -acervuline parts of the ordinary form. - - -Eozoon Bavaricum, _Gümbel_. - -Composed of small acervuline chambers, separated by contorted walls, -and associated with broad plate-like chambers below. Large canals -in the thicker parts of the intermediate skeleton. Differs from _E. -Canadense_ in its smaller and more contorted chambers. Age probably -Huronian. - - -_Genus_ ARCHÆOSPHERINA. - -A provisional genus, to include rounded solitary chambers, or -globigerine assemblages of such chambers, with the cell-wall -surrounding them tubulated as in Eozoon. They may be distinct -organisms, or gemmæ or detached fragments of Eozoon. Some of them -much resemble the bodies figured by Dr. Carpenter, as gemmæ or ova -and primitive chambers of Orbitolites. They are very abundant on some -of the strata surfaces of the limestone at Côte St. Pierre. Age Lower -Laurentian. - - -SYSTEMATIC POSITION OF EOZOON. - -The unsettled condition of the classification of the Protozoa, and our -absolute ignorance of the animal matter of Eozoon, render it difficult -to make any statement on this subject more definite than the somewhat -vague intimations given in the text. My own views at present, based on -the study of recent and fossil forms, and of the writings of Carpenter, -Max Schultze, Carter, Wallich, Haeckel, and Clarepede, may be stated, -though with some diffidence, as follows:-- - -I. The class _Rhizopoda_ includes all the sarcodous animals whose only -external organs are pseudopodia, and is the lowest class in the animal -kingdom. Immediately above it are the classes of the Sponges and of the -flagellate and ciliate Infusoria, which rise from it like two diverging -branches. - -II. The group of Rhizopods, as thus defined, includes three leading -_orders_, which, in descending grade, are as follows:-- - - (_a_) _Lobosa_, or Amœboid Rhizopods, including those with - distinct nucleus and pulsating vesicle, and thick lobulate - pseudopodia--naked, or in membranous coverings. - - (_b_) _Radiolaria_, or Polycistius and their allies, including - those with thread-like pseudopodia, with or without a - nucleus, and with the skeleton, when present, silicious. - - (_c_) _Reticularia_, or Foraminifera and their allies, including - those with thread-like and reticulating pseudopodia, with - granular matter instead of a nucleus, and with calcareous, - membranous, or arenaceous skeletons. - -The place of _Eozoon_ will be in the lowest order, _Reticularia_. - -III. The order _Reticularia_ may be farther divided into two -_sub-orders_, as follows:-- - - (_a_) _Perforata_--having calcareous skeletons penetrated with - pores. - - (_b_) _Imperforata_--having calcareous, membranous, or arenaceous - skeletons, without pores. - -The place of Eozoon will be in the higher sub-order, _Perforata_. - -IV. The sub-order _Perforata_ includes three _families_--the -_Nummulinidæ_, _Globigerinidæ_, and _Lagemdæ_. Of these Carpenter -regards the Nummulinidæ as the highest in rank. - -The place of Eozoon will be in the family _Nummulinidæ_, or between -this and the next family. This oldest known Protozoon would thus belong -to the highest family in the highest sub-order of the lowest class of -animals. - - -THE LATE SIR WILLIAM E. LOGAN. - -When writing the dedication of this work, I little thought that the -eminent geologist and valued friend to whom it gave me so much pleasure -to tender this tribute of respect, would have passed away before its -publication. But so it is, and we have now to mourn, not only Lyell, -who so frankly accepted the evidence in favour of Eozoon, but Logan, -who so boldly from the first maintained its true nature as a fossil. -This boldness on his part is the more remarkable and impressive, from -the extreme caution by which he was characterized, and which induced -him to take the most scrupulous pains to verify every new fact before -committing himself to it. Though Sir William's early work in the Welsh -coal-fields, his organization and management of the Survey of Canada, -and his reducing to order for the first time all the widely extended -Palæozoic formations of that great country, must always constitute -leading elements in his reputation, I think that in nothing does he -deserve greater credit than in the skill and genius with which he -attacked the difficult problem of the Laurentian rocks, unravelled -their intricacies, and ascertained their true nature as sediments, and -the leading facts of their arrangement and distribution. The discovery -of Eozoon was one of the results of this great work; and it was the -firm conviction to which Sir William had attained of the sedimentary -character of the rocks, which rendered his mind open to the evidence of -these contained fossils, and induced him even to expect the discovery -of them. - -This would not be the proper place to dwell on the general character -and work of Sir William Logan, but I cannot close without referring to -his untiring industry, his enthusiasm in the investigation of nature, -his cheerful and single-hearted disposition, his earnest public spirit -and patriotism--qualities which won for him the regard even of those -who could little appreciate the details of his work, and which did much -to enable him to attain to the success which he achieved. - - - - -INDEX. - - - Acervuline explained, 66. - - Acervuline Variety of Eozoon, 135. - - Aggregative Growth of Animals, 213. - - Aker Limestone, 197. - - Amity Limestone, 197. - - Amœba described, 59. - - Annelid Burrows, 133, 139. - - Archæospherinæ, 137, 148. - - Archæocyathus, 151. - - Arisaig, Supposed Eozoon of, 140. - - - Bathybius, 65. - - Bavaria, Eozoon of, 148. - - Beginning of Life, 215. - - Billings, Mr.,--referred to, 41; - on Archæocyathus, 151; - on Receptaculites, 163. - - - Calumet, Eozoon of, 38. - - Calcarina, 74. - - Calcite filling Tubes of Eozoon, 98. - - Canal System of Eozoon, 40, 66, 107, 176, 181. - - Carpenter--referred to, 41; - on Eozoon, 82; - Reply to Carter, 204. - - Caunopora, 158. - - Chrysotile Veins, 107, 180. - - Chemistry of Eozoon, 199. - - Coccoliths, 70. - - Cœnostroma, 158. - - Contemporaries of Eozoon, 127. - - Côte St. Pierre, 20. - - - Derivation applied to Eozoon, 225. - - Discovery of Eozoon, 35. - - - Eozoic Time, 7. - - Eozoon,--Discovery of, 35; - Structure of, 65; - Growth of, 70; - Fragments of, 74; - Description of, 65, 77 (also Appendix); - Note on by Dr. Carpenter, 82; - Thickened Walls of, 66; - Preservation of, 100; - Pores filled with Calcite, 97, 109; - with Pyroxene, 108; - with Serpentine, 101; - with Dolomite, 109; - in Limestone, 110; - Defective Specimens of, 113; - how Mineralized, 102, 116; - its Contemporaries, 127; - Acervuline Variety of, 135; - Variety _Minor_ of, 135; - Acadianum, 140; - Bavaricum, 148; - Localities of, 166; - Harmony of with other Fossils, 171; - Summary of evidence relating to, 176. - - - Faulted Eozoon, 182. - - Foraminifera, Notice of, 61. - - Fossils, how Mineralized, 93. - - Fusulina, 74. - - - Glauconite, 100, 125, 220. - - Graphite of Laurentian, 18, 27. - - Green-sand, 99. - - Grenville, Eozoon of, 38. - - Gümbel on Laurentian Fossils, 124; - on Eozoon Bavaricum, 141. - - - Hastings, Rocks of, 57. - - History of Discovery of Eozoon, 35. - - Honeyman, Dr., referred to, 140. - - Hunt, Dr. Sterry, referred to, 35; - on Mineralization of Eozoon, 115; - on Silurian Fossils infiltrated with Silicates, 121; - on Minerals of the Laurentian, 123; - on Laurentian Life, 27; - his Reply to Objections, 199. - - Huronian Rocks, 9. - - - Intermediate Skeleton, 64. - - Iron Ores of Laurentian, 19. - - - Jones, Prof. T. Rupert, on Eozoon, 42. - - - King, Prof., his Objections, 184. - - - Labrador Feldspar, 13. - - Laurentian Rocks, 7; - Fossils of, 130; - Graphite of, 18, 27; - Iron Ores of, 19; - Limestones of, 17. - - Limestones, Laurentian, 17; - Silurian, 98. - - Localities of Eozoon, 166. - - Loftusia, 164. - - Logan, Sir Wm., referred to, 36; - on Laurentian, 24; - on Nature of Eozoon, 37; - Geological Relations of Eozoon, 48; - on Additional Specimens of Eozoon, 52. - - Loganite in Eozoon, 36, 102. - - Lowe, Mr., referred to, 38. - - Long Lake, Specimens from, 91. - - Lyell, Sir C., on Eozoon, 234. - - - Madoc, Specimens from, 132. - - Maps of Laurentian, 7, 16. - - MacMullen, Mr., referred to, 37. - - Metamorphism of Rocks, 13, 34. - - Mineralization of Eozoon, 101; - of Fossils, 93; - Hunt on, 115. - - - Nicholson on Stromatopora, 165. - - Nummulites, 73. - - Nummuline Wall, 43, 65, 106, 176, 181. - - - Objections answered, 169, 188. - - - Parkeria, 164. - - Petite Nation, 20, 43. - - Pole Hill, Specimens from, 121. - - Proper Wall, 43, 65, 106, 176, 181. - - Preservation of Eozoon, 93. - - Protozoa, their Nature, 59, 207. - - Pseudomorphism, 200. - - Pyroxene filling Eozoon, 108. - - - Red Clay of Pacific, 222. - - Red Chalk, 222. - - Reply to Objections, 167, 188. - - Receptaculites, 162. - - Robb, Mr., referred to, 120. - - Rowney, Prof., Objections of, 184. - - - Serpentine mineralizing Eozoon, 102. - - Silicates mineralizing Fossils, 100, 103, 121, 220. - - Silurian Fossils infiltrated with Silicates, 121. - - Steinhag, Eozoon of, 146. - - Stromatopora, 37, 156. - - Stromatoporidæ, 165. - - Supplemental Skeleton, 64. - - - Table of Formations, 6. - - Trinity Cape, 10. - - Tubuli Explained, 66, 106. - - - Varieties of Eozoon, 135, 236. - - Vennor, Mr., referred to, 46, 57. - - - Wentworth Specimens, 91. - - Weston, Mr., referred to, 20, 40, 162. - - Wilson, Dr., referred to, 36. - - Worm-burrows in the Laurentian, 133, 139. - - -Butler & Tanner. The Selwood Printing Works. Frome, and London. - - - * * * * * - - - - -Transcriber Notes - - -The label Plate II was added to the illustration's page. 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