diff options
| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 05:20:06 -0700 |
|---|---|---|
| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 05:20:06 -0700 |
| commit | 2605eee39587aab3519971c6143c8bf43c396890 (patch) | |
| tree | 9b68dbff8bb18572903c85726704f3ab4b1d795d | |
| -rw-r--r-- | .gitattributes | 3 | ||||
| -rw-r--r-- | 2924-h.zip | bin | 0 -> 21957 bytes | |||
| -rw-r--r-- | 2924-h/2924-h.htm | 1075 | ||||
| -rw-r--r-- | 2924.txt | 983 | ||||
| -rw-r--r-- | 2924.zip | bin | 0 -> 20862 bytes | |||
| -rw-r--r-- | LICENSE.txt | 11 | ||||
| -rw-r--r-- | README.md | 2 | ||||
| -rw-r--r-- | old/thx0410.txt | 920 | ||||
| -rw-r--r-- | old/thx0410.zip | bin | 0 -> 19286 bytes |
9 files changed, 2994 insertions, 0 deletions
diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/2924-h.zip b/2924-h.zip Binary files differnew file mode 100644 index 0000000..6c0e97d --- /dev/null +++ b/2924-h.zip diff --git a/2924-h/2924-h.htm b/2924-h/2924-h.htm new file mode 100644 index 0000000..c41d658 --- /dev/null +++ b/2924-h/2924-h.htm @@ -0,0 +1,1075 @@ +<?xml version="1.0" encoding="us-ascii"?> + +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd" > + +<html xmlns="http://www.w3.org/1999/xhtml" lang="en"> + <head> + <title> + Lecture to Working Men, No. 3 (of 6), THE PERPETUATION OF LIVING BEINGS by + Thomas H. Huxley + </title> + <style type="text/css" xml:space="preserve"> + + body { margin:5%; background:#faebd0; text-align:justify} + P { text-indent: 1em; margin-top: .25em; margin-bottom: .25em; } + H1,H2,H3,H4,H5,H6 { text-align: center; margin-left: 15%; margin-right: 15%; } + hr { width: 50%; text-align: center;} + .foot { margin-left: 20%; margin-right: 20%; text-align: justify; text-indent: -3em; font-size: 90%; } + blockquote {font-size: 97%; font-style: italic; margin-left: 10%; margin-right: 10%;} + .mynote {background-color: #DDE; color: #000; padding: .5em; margin-left: 10%; margin-right: 10%; font-family: sans-serif; font-size: 95%;} + .toc { margin-left: 10%; margin-bottom: .75em;} + .toc2 { margin-left: 20%;} + div.fig { display:block; margin:0 auto; text-align:center; } + div.middle { margin-left: 20%; margin-right: 20%; text-align: justify; } + .figleft {float: left; margin-left: 0%; margin-right: 1%;} + .figright {float: right; margin-right: 0%; margin-left: 1%;} + .pagenum {display:inline; font-size: 70%; font-style:normal; + margin: 0; padding: 0; position: absolute; right: 1%; + text-align: right;} + pre { font-style: italic; font-size: 90%; margin-left: 10%;} + +</style> + </head> + <body> +<pre xml:space="preserve"> + +The Project Gutenberg EBook of The Perpetuation Of Living Beings, +Hereditary Transmission And Variation, by Thomas H. Huxley + +This eBook is for the use of anyone anywhere 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 + + +Title: The Perpetuation Of Living Beings, Hereditary Transmission And Variation + Lecture IV. (of VI.), Lectures To Working Men, at the + Museum of Practical Geology, 1863, On Darwin's work: "Origin + of Species". + +Author: Thomas H. Huxley + +Release Date: January 4, 2009 [EBook #2924] +Last Updated: January 22, 2013 + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK HEREDITARY TRANSMISSION *** + + + + +Produced by Amy E. Zelmer, and David Widger + + + + + + +</pre> + <p> + <br /><br /> + </p> + <h1> + THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND VARIATION + </h1> + <p> + <br /> + </p> + <h3> + Lecture III. (of VI.), "Lectures To Working Men", at the Museum of + Practical Geology, 1863, On Darwin's work: "Origin of Species". + </h3> + <p> + <br /><br /> + </p> + <h2> + By Thomas H. Huxley + </h2> + <p> + <br /> <br /> + </p> + <hr /> + <p> + <br /> <br /> + </p> + <p> + The inquiry which we undertook, at our last meeting, into the state of our + knowledge of the causes of the phenomena of organic nature,—of the + past and of the present,—resolved itself into two subsidiary + inquiries: the first was, whether we know anything, either historically or + experimentally, of the mode of origin of living beings; the second + subsidiary inquiry was, whether, granting the origin, we know anything + about the perpetuation and modifications of the forms of organic beings. + The reply which I had to give to the first question was altogether + negative, and the chief result of my last lecture was, that, neither + historically nor experimentally, do we at present know anything whatsoever + about the origin of living forms. We saw that, historically, we are not + likely to know anything about it, although we may perhaps learn something + experimentally; but that at present we are an enormous distance from the + goal I indicated. + </p> + <p> + I now, then, take up the next question, What do we know of the + reproduction, the perpetuation, and the modifications of the forms of + living beings, supposing that we have put the question as to their + origination on one side, and have assumed that at present the causes of + their origination are beyond us, and that we know nothing about them? Upon + this question the state of our knowledge is extremely different; it is + exceedingly large, and, if not complete, our experience is certainly most + extensive. It would be impossible to lay it all before you, and the most I + can do, or need do to-night, is to take up the principal points and put + them before you with such prominence as may subserve the purposes of our + present argument. + </p> + <p> + The method of the perpetuation of organic beings is of two kinds,—the + asexual and the sexual. In the first the perpetuation takes place from and + by a particular act of an individual organism, which sometimes may not be + classed as belonging to any sex at all. In the second case, it is in + consequence of the mutual action and interaction of certain portions of + the organisms of usually two distinct individuals,—the male and the + female. The cases of asexual perpetuation are by no means so common as the + cases of sexual perpetuation; and they are by no means so common in the + animal as in the vegetable world. You are all probably familiar with the + fact, as a matter of experience, that you can propagate plants by means of + what are called "cuttings;" for example, that by taking a cutting from a + geranium plant, and rearing it properly, by supplying it with light and + warmth and nourishment from the earth, it grows up and takes the form of + its parent, having all the properties and peculiarities of the original + plant. + </p> + <p> + Sometimes this process, which the gardener performs artificially, takes + place naturally; that is to say, a little bulb, or portion of the plant, + detaches itself, drops off, and becomes capable of growing as a separate + thing. That is the case with many bulbous plants, which throw off in this + way secondary bulbs, which are lodged in the ground and become developed + into plants. This is an asexual process, and from it results the + repetition or reproduction of the form of the original being from which + the bulb proceeds. + </p> + <p> + Among animals the same thing takes place. Among the lower forms of animal + life, the infusorial animalculae we have already spoken of throw off + certain portions, or break themselves up in various directions, sometimes + transversely or sometimes longitudinally; or they may give off buds, which + detach themselves and develop into their proper forms. There is the common + fresh-water Polype, for instance, which multiplies itself in this way. + Just in the same way as the gardener is able to multiply and reproduce the + peculiarities and characters of particular plants by means of cuttings, so + can the physiological experimentalist—as was shown by the Abbe + Trembley many years ago—so can he do the same thing with many of the + lower forms of animal life. M. de Trembley showed that you could take a + polype and cut it into two, or four, or many pieces, mutilating it in all + directions, and the pieces would still grow up and reproduce completely + the original form of the animal. These are all cases of asexual + multiplication, and there are other instances, and still more + extraordinary ones, in which this process takes place naturally, in a more + hidden, a more recondite kind of way. You are all of you familiar with + those little green insects, the 'Aphis' or blight, as it is called. These + little animals, during a very considerable part of their existence, + multiply themselves by means of a kind of internal budding, the buds being + developed into essentially asexual animals, which are neither male nor + female; they become converted into young 'Aphides', which repeat the + process, and their offspring after them, and so on again; you may go on + for nine or ten, or even twenty or more successions; and there is no very + good reason to say how soon it might terminate, or how long it might not + go on if the proper conditions of warmth and nourishment were kept up. + </p> + <p> + Sexual reproduction is quite a distinct matter. Here, in all these cases, + what is required is the detachment of two portions of the parental + organisms, which portions we know as the egg and the spermatozoon. In + plants it is the ovule and the pollen-grain, as in the flowering plants, + or the ovule and the antherozooid, as in the flowerless. Among all forms + of animal life, the spermatozoa proceed from the male sex, and the egg is + the product of the female. Now, what is remarkable about this mode of + reproduction is this, that the egg by itself, or the spermatozoa by + themselves, are unable to assume the parental form; but if they be brought + into contact with one another, the effect of the mixture of organic + substances proceeding from two sources appears to confer an altogether new + vigour to the mixed product. This process is brought about, as we all + know, by the sexual intercourse of the two sexes, and is called the act of + impregnation. The result of this act on the part of the male and female + is, that the formation of a new being is set up in the ovule or egg; this + ovule or egg soon begins to be divided and subdivided, and to be fashioned + into various complex organisms, and eventually to develop into the form of + one of its parents, as I explained in the first lecture. These are the + processes by which the perpetuation of organic beings is secured. Why + there should be the two modes—why this re-invigoration should be + required on the part of the female element we do not know; but it is most + assuredly the fact, and it is presumable, that, however long the process + of asexual multiplication could be continued, I say there is good reason + to believe that it would come to an end if a new commencement were not + obtained by a conjunction of the two sexual elements. + </p> + <p> + That character which is common to these two distinct processes is this, + that, whether we consider the reproduction, or perpetuation, or + modification of organic beings as they take place asexually, or as they + may take place sexually,—in either case, I say, the offspring has a + constant tendency to assume, speaking generally, the character of the + parent. As I said just now, if you take a slip of a plant, and tend it + with care, it will eventually grow up and develop into a plant like that + from which it had sprung; and this tendency is so strong that, as + gardeners know, this mode of multiplying by means of cuttings is the only + secure mode of propagating very many varieties of plants; the peculiarity + of the primitive stock seems to be better preserved if you propagate it by + means of a slip than if you resort to the sexual mode. + </p> + <p> + Again, in experiments upon the lower animals, such as the polype, to which + I have referred, it is most extraordinary that, although cut up into + various pieces, each particular piece will grow up into the form of the + primitive stock; the head, if separated, will reproduce the body and the + tail; and if you cut off the tail, you will find that that will reproduce + the body and all the rest of the members, without in any way deviating + from the plan of the organism from which these portions have been + detached. And so far does this go, that some experimentalists have + carefully examined the lower orders of animals,—among them the Abbe + Spallanzani, who made a number of experiments upon snails and salamanders,—and + have found that they might mutilate them to an incredible extent; that you + might cut off the jaw or the greater part of the head, or the leg or the + tail, and repeat the experiment several times, perhaps, cutting off the + same member again and again; and yet each of those types would be + reproduced according to the primitive type: nature making no mistake, + never putting on a fresh kind of leg, or head, or tail, but always tending + to repeat and to return to the primitive type. + </p> + <p> + It is the same in sexual reproduction: it is a matter of perfectly common + experience, that the tendency on the part of the offspring always is, + speaking broadly, to reproduce the form of the parents. The proverb has it + that the thistle does not bring forth grapes; so, among ourselves, there + is always a likeness, more or less marked and distinct, between children + and their parents. That is a matter of familiar and ordinary observation. + We notice the same thing occurring in the cases of the domestic animals—dogs, + for instance, and their offspring. In all these cases of propagation and + perpetuation, there seems to be a tendency in the offspring to take the + characters of the parental organisms. To that tendency a special name is + given—it is called 'Atavism', it expresses this tendency to revert + to the ancestral type, and comes from the Latin word 'atavus', ancestor. + </p> + <p> + Well, this 'Atavism' which I shall speak of, is, as I said before, one of + the most marked and striking tendencies of organic beings; but, side by + side with this hereditary tendency there is an equally distinct and + remarkable tendency to variation. The tendency to reproduce the original + stock has, as it were, its limits, and side by side with it there is a + tendency to vary in certain directions, as if there were two opposing + powers working upon the organic being, one tending to take it in a + straight line, and the other tending to make it diverge from that straight + line, first to one side and then to the other. + </p> + <p> + So that you see these two tendencies need not precisely contradict one + another, as the ultimate result may not always be very remote from what + would have been the case if the line had been quite straight. + </p> + <p> + This tendency to variation is less marked in that mode of propagation + which takes place asexually; it is in that mode that the minor characters + of animal and vegetable structures are most completely preserved. Still, + it will happen sometimes, that the gardener, when he has planted a cutting + of some favourite plant, will find, contrary to his expectation, that the + slip grows up a little different from the primitive stock—that it + produces flowers of a different colour or make, or some deviation in one + way or another. This is what is called the 'sporting' of plants. + </p> + <p> + In animals the phenomena of asexual propagation are so obscure, that at + present we cannot be said to know much about them; but if we turn to that + mode of perpetuation which results from the sexual process, then we find + variation a perfectly constant occurrence, to a certain extent; and, + indeed, I think that a certain amount of variation from the primitive + stock is the necessary result of the method of sexual propagation itself; + for, inasmuch as the thing propagated proceeds from two organisms of + different sexes and different makes and temperaments, and as the offspring + is to be either of one sex or the other, it is quite clear that it cannot + be an exact diagonal of the two, or it would be of no sex at all; it + cannot be an exact intermediate form between that of each of its parents—it + must deviate to one side or the other. You do not find that the male + follows the precise type of the male parent, nor does the female always + inherit the precise characteristics of the mother,—there is always a + proportion of the female character in the male offspring, and of the male + character in the female offspring. That must be quite plain to all of you + who have looked at all attentively on your own children or those of your + neighbours; you will have noticed how very often it may happen that the + son shall exhibit the maternal type of character, or the daughter possess + the characteristics of the father's family. There are all sorts of + intermixtures and intermediate conditions between the two, where + complexion, or beauty, or fifty other different peculiarities belonging to + either side of the house, are reproduced in other members of the same + family. Indeed, it is sometimes to be remarked in this kind of variation, + that the variety belongs, strictly speaking, to neither of the immediate + parents; you will see a child in a family who is not like either its + father or its mother; but some old person who knew its grandfather or + grandmother, or, it may be, an uncle, or, perhaps, even a more distant + relative, will see a great similarity between the child and one of these. + In this way it constantly happens that the characteristic of some previous + member of the family comes out and is reproduced and recognised in the + most unexpected manner. + </p> + <p> + But apart from that matter of general experience, there are some cases + which put that curious mixture in a very clear light. You are aware that + the offspring of the Ass and the Horse, or rather of the he-Ass and the + Mare, is what is called a Mule; and, on the other hand, the offspring of + the Stallion and the she-Ass is what is called a 'Hinny'. I never saw one + myself; but they have been very carefully studied. Now, the curious thing + is this, that although you have the same elements in the experiment in + each case, the offspring is entirely different in character, according as + the male influence comes from the Ass or the Horse. Where the Ass is the + male, as in the case of the Mule, you find that the head is like that of + the Ass, that the ears are long, the tail is tufted at the end, the feet + are small, and the voice is an unmistakable bray; these are all points of + similarity to the Ass; but, on the other hand, the barrel of the body and + the cut of the neck are much more like those of the Mare. Then, if you + look at the Hinny,—the result of the union of the Stallion and the + she-Ass, then you find it is the Horse that has the predominance; that the + head is more like that of the Horse, the ears are shorter, the legs + coarser, and the type is altogether altered; while the voice, instead of + being a bray, is the ordinary neigh of the Horse. Here, you see, is a most + curious thing: you take exactly the same elements, Ass and Horse, but you + combine the sexes in a different manner, and the result is modified + accordingly. You have in this case, however, a result which is not general + and universal—there is usually an important preponderance, but not + always on the same side. + </p> + <p> + Here, then, is one intelligible, and, perhaps, necessary cause of + variation: the fact, that there are two sexes sharing in the production of + the offspring, and that the share taken by each is different and variable, + not only for each combination, but also for different members of the same + family. + </p> + <p> + Secondly, there is a variation, to a certain extent—though, in all + probability, the influence of this cause has been very much exaggerated—but + there is no doubt that variation is produced, to a certain extent, by what + are commonly known as external conditions,—such as temperature, + food, warmth, and moisture. In the long run, every variation depends, in + some sense, upon external conditions, seeing that everything has a cause + of its own. I use the term "external conditions" now in the sense in which + it is ordinarily employed: certain it is, that external conditions have a + definite effect. You may take a plant which has single flowers, and by + dealing with the soil, and nourishment, and so on, you may by-and-by + convert single flowers into double flowers, and make thorns shoot out into + branches. You may thicken or make various modifications in the shape of + the fruit. In animals, too, you may produce analogous changes in this way, + as in the case of that deep bronze colour which persons rarely lose after + having passed any length of time in tropical countries. You may also alter + the development of the muscles very much, by dint of training; all the + world knows that exercise has a great effect in this way; we always expect + to find the arm of a blacksmith hard and wiry, and possessing a large + development of the brachial muscles. No doubt training, which is one of + the forms of external conditions, converts what are originally only + instructions, teachings, into habits, or, in other words, into + organizations, to a great extent; but this second cause of variation + cannot be considered to be by any means a large one. The third cause that + I have to mention, however, is a very extensive one. It is one that, for + want of a better name, has been called "spontaneous variation;" which + means that when we do not know anything about the cause of phenomena, we + call it spontaneous. In the orderly chain of causes and effects in this + world, there are very few things of which it can be said with truth that + they are spontaneous. Certainly not in these physical matters,—in + these there is nothing of the kind,—everything depends on previous + conditions. But when we cannot trace the cause of phenomena, we call them + spontaneous. + </p> + <p> + Of these variations, multitudinous as they are, but little is known with + perfect accuracy. I will mention to you some two or three cases, because + they are very remarkable in themselves, and also because I shall want to + use them afterwards. Reaumur, a famous French naturalist, a great many + years ago, in an essay which he wrote upon the art of hatching chickens,—which + was indeed a very curious essay,—had occasion to speak of variations + and monstrosities. One very remarkable case had come under his notice of a + variation in the form of a human member, in the person of a Maltese, of + the name of Gratio Kelleia, who was born with six fingers upon each hand, + and the like number of toes to each of his feet. That was a case of + spontaneous variation. Nobody knows why he was born with that number of + fingers and toes, and as we don't know, we call it a case of "spontaneous" + variation. There is another remarkable case also. I select these, because + they happen to have been observed and noted very carefully at the time. It + frequently happens that a variation occurs, but the persons who notice it + do not take any care in noting down the particulars, until at length, when + inquiries come to be made, the exact circumstances are forgotten; and + hence, multitudinous as may be such "spontaneous" variations, it is + exceedingly difficult to get at the origin of them. + </p> + <p> + The second case is one of which you may find the whole details in the + "Philosophical Transactions" for the year 1813, in a paper communicated by + Colonel Humphrey to the President of the Royal Society,—"On a new + Variety in the Breed of Sheep," giving an account of a very remarkable + breed of sheep, which at one time was well known in the northern states of + America, and which went by the name of the Ancon or the Otter breed of + sheep. In the year 1791, there was a farmer of the name of Seth Wright in + Massachusetts, who had a flock of sheep, consisting of a ram and, I think, + of some twelve or thirteen ewes. Of this flock of ewes, one at the + breeding-time bore a lamb which was very singularly formed; it had a very + long body, very short legs, and those legs were bowed! I will tell you + by-and-by how this singular variation in the breed of sheep came to be + noted, and to have the prominence that it now has. For the present, I + mention only these two cases; but the extent of variation in the breed of + animals is perfectly obvious to any one who has studied natural history + with ordinary attention, or to any person who compares animals with others + of the same kind. It is strictly true that there are never any two + specimens which are exactly alike; however similar, they will always + differ in some certain particular. + </p> + <p> + Now let us go back to Atavism,—to the hereditary tendency I spoke + of. What will come of a variation when you breed from it, when Atavism + comes, if I may say so, to intersect variation? The two cases of which I + have mentioned the history, give a most excellent illustration of what + occurs. Gratio Kelleia, the Maltese, married when he was twenty-two years + of age, and, as I suppose there were no six-fingered ladies in Malta, he + married an ordinary five-fingered person. The result of that marriage was + four children; the first, who was christened Salvator, had six fingers and + six toes, like his father; the second was George, who had five fingers and + toes, but one of them was deformed, showing a tendency to variation; the + third was Andre; he had five fingers and five toes, quite perfect; the + fourth was a girl, Marie; she had five fingers and five toes, but her + thumbs were deformed, showing a tendency toward the sixth. + </p> + <p> + These children grew up, and when they came to adult years, they all + married, and of course it happened that they all married five-fingered and + five-toed persons. Now let us see what were the results. Salvator had four + children; they were two boys, a girl, and another boy; the first two boys + and the girl were six-fingered and six-toed like their grandfather; the + fourth boy had only five fingers and five toes. George had only four + children; there were two girls with six fingers and six toes; there was + one girl with six fingers and five toes on the right side, and five + fingers and five toes on the left side, so that she was half and half. The + last, a boy, had five fingers and five toes. The third, Andre, you will + recollect, was perfectly well-formed, and he had many children whose hands + and feet were all regularly developed. Marie, the last, who, of course, + married a man who had only five fingers, had four children; the first, a + boy, was born with six toes, but the other three were normal. + </p> + <p> + Now observe what very extraordinary phenomena are presented here. You have + an accidental variation arising from what you may call a monstrosity; you + have that monstrosity tendency or variation diluted in the first instance + by an admixture with a female of normal construction, and you would + naturally expect that, in the results of such an union, the monstrosity, + if repeated, would be in equal proportion with the normal type; that is to + say, that the children would be half and half, some taking the peculiarity + of the father, and the others being of the purely normal type of the + mother; but you see we have a great preponderance of the abnormal type. + Well, this comes to be mixed once more with the pure, the normal type, and + the abnormal is again produced in large proportion, notwithstanding the + second dilution. Now what would have happened if these abnormal types had + intermarried with each other; that is to say, suppose the two boys of + Salvator had taken it into their heads to marry their first cousins, the + two first girls of George, their uncle? You will remember that these are + all of the abnormal type of their grandfather. The result would probably + have been, that their offspring would have been in every case a further + development of that abnormal type. You see it is only in the fourth, in + the person of Marie, that the tendency, when it appears but slightly in + the second generation, is washed out in the third, while the progeny of + Andre, who escaped in the first instance, escape altogether. + </p> + <p> + We have in this case a good example of nature's tendency to the + perpetuation of a variation. Here it is certainly a variation which + carried with it no use or benefit; and yet you see the tendency to + perpetuation may be so strong, that, notwithstanding a great admixture of + pure blood, the variety continues itself up to the third generation, which + is largely marked with it. In this case, as I have said, there was no + means of the second generation intermarrying with any but five-fingered + persons, and the question naturally suggests itself, What would have been + the result of such marriage? Reaumur narrates this case only as far as the + third generation. Certainly it would have been an exceedingly curious + thing if we could have traced this matter any further; had the cousins + intermarried, a six-fingered variety of the human race might have been set + up. + </p> + <p> + To show you that this supposition is by no means an unreasonable one, let + me now point out what took place in the case of Seth Wright's sheep, where + it happened to be a matter of moment to him to obtain a breed or raise a + flock of sheep like that accidental variety that I have described—and + I will tell you why. In that part of Massachusetts where Seth Wright was + living, the fields were separated by fences, and the sheep, which were + very active and robust, would roam abroad, and without much difficulty + jump over these fences into other people's farms. As a matter of course, + this exuberant activity on the part of the sheep constantly gave rise to + all sorts of quarrels, bickerings, and contentions among the farmers of + the neighbourhood; so it occurred to Seth Wright, who was, like his + successors, more or less 'cute, that if he could get a stock of sheep like + those with the bandy legs, they would not be able to jump over the fences + so readily, and he acted upon that idea. He killed his old ram, and as + soon as the young one arrived at maturity, he bred altogether from it. The + result was even more striking than in the human experiment which I + mentioned just now. Colonel Humphreys testifies that it always happened + that the offspring were either pure Ancons or pure ordinary sheep; that in + no case was there any mixing of the Ancons with the others. In consequence + of this, in the course of a very few years, the farmer was able to get a + very considerable flock of this variety, and a large number of them were + spread throughout Massachusetts. Most unfortunately, however—I + suppose it was because they were so common—nobody took enough notice + of them to preserve their skeletons; and although Colonel Humphreys states + that he sent a skeleton to the President of the Royal Society at the same + time that he forwarded his paper, I am afraid that the variety has + entirely disappeared; for a short time after these sheep had become + prevalent in that district, the Merino sheep were introduced; and as their + wool was much more valuable, and as they were a quiet race of sheep, and + showed no tendency to trespass or jump over fences, the Otter breed of + sheep, the wool of which was inferior to that of the Merino, was gradually + allowed to die out. + </p> + <p> + You see that these facts illustrate perfectly well what may be done if you + take care to breed from stocks that are similar to each other. After + having got a variation, if, by crossing a variation with the original + stock, you multiply that variation, and then take care to keep that + variation distinct from the original stock, and make them breed together,—then + you may almost certainly produce a race whose tendency to continue the + variation is exceedingly strong. + </p> + <p> + This is what is called "selection"; and it is by exactly the same process + as that by which Seth Wright bred his Ancon sheep, that our breeds of + cattle, dogs, and fowls, are obtained. There are some possibilities of + exception, but still, speaking broadly, I may say that this is the way in + which all our varied races of domestic animals have arisen; and you must + understand that it is not one peculiarity or one characteristic alone in + which animals may vary. There is not a single peculiarity or + characteristic of any kind, bodily or mental, in which offspring may not + vary to a certain extent from the parent and other animals. + </p> + <p> + Among ourselves this is well known. The simplest physical peculiarity is + mostly reproduced. I know a case of a man whose wife has the lobe of one + of her ears a little flattened. An ordinary observer might scarcely notice + it, and yet every one of her children has an approximation to the same + peculiarity to some extent. If you look at the other extreme, too, the + gravest diseases, such as gout, scrofula, and consumption, may be handed + down with just the same certainty and persistence as we noticed in the + perpetuation of the bandy legs of the Ancon sheep. + </p> + <p> + However, these facts are best illustrated in animals, and the extent of + the variation, as is well known, is very remarkable in dogs. For example, + there are some dogs very much smaller than others; indeed, the variation + is so enormous that probably the smallest dog would be about the size of + the head of the largest; there are very great variations in the structural + forms not only of the skeleton but also in the shape of the skull, and in + the proportions of the face and the disposition of the teeth. + </p> + <p> + The Pointer, the Retriever, Bulldog, and the Terrier, differ very greatly, + and yet there is every reason to believe that every one of these races has + arisen from the same source,—that all the most important races have + arisen by this selective breeding from accidental variation. + </p> + <p> + A still more striking case of what may be done by selective breeding, and + it is a better case, because there is no chance of that partial infusion + of error to which I alluded, has been studied very carefully by Mr. + Darwin,—the case of the domestic pigeons. I dare say there may be + some among you who may be pigeon 'fanciers', and I wish you to understand + that in approaching the subject, I would speak with all humility and + hesitation, as I regret to say that I am not a pigeon fancier. I know it + is a great art and mystery, and a thing upon which a man must not speak + lightly; but I shall endeavour, as far as my understanding goes, to give + you a summary of the published and unpublished information which I have + gained from Mr. Darwin. + </p> + <p> + Among the enormous variety,—I believe there are somewhere about a + hundred and fifty kinds of pigeons,—there are four kinds which may + be selected as representing the extremest divergences of one kind from + another. Their names are the Carrier, the Pouter, the Fantail, and the + Tumbler. In the large diagrams they are each represented in their relative + sizes to each other. This first one is the Carrier; you will notice this + large excrescence on its beak; it has a comparatively small head; there is + a bare space round the eyes; it has a long neck, a very long beak, very + strong legs, large feet, long wings, and so on. The second one is the + Pouter, a very large bird, with very long legs and beak. It is called the + Pouter because it is in the habit of causing its gullet to swell up by + inflating it with air. I should tell you that all pigeons have a tendency + to do this at times, but in the Pouter it is carried to an enormous + extent. The birds appear to be quite proud of their power of swelling and + puffing themselves out in this way; and I think it is about as droll a + sight as you can well see to look at a cage full of these pigeons puffing + and blowing themselves out in this ridiculous manner. + </p> + <p> + The third kind I mentioned—the Fantail—is a small bird, with + exceedingly small legs and a very small beak. It is most curiously + distinguished by the size and extent of its tail, which, instead of + containing twelve feathers, may have many more,—say thirty, or even + more—I believe there are some with as many as forty-two. This bird + has a curious habit of spreading out the feathers of its tail in such a + way that they reach forward, and touch its head; and if this can be + accomplished, I believe it is looked upon as a point of great beauty. + </p> + <p> + But here is the last great variety,—the Tumbler; and of that great + variety, one of the principal kinds, and one most prized, is the specimen + represented here—the short-faced Tumbler. Its beak is reduced to a + mere nothing. Just compare the beak of this one and that of the first one, + the Carrier—I believe the orthodox comparison of the head and beak + of a thoroughly well-bred Tumbler is to stick an oat into a cherry, and + that will give you the proper relative proportions of the head and beak. + The feet and legs are exceedingly small, and the bird appears to be quite + a dwarf when placed side by side with this great Carrier. + </p> + <p> + These are differences enough in regard to their external appearance; but + these differences are by no means the whole or even the most important of + the differences which obtain between these birds. There is hardly a single + point of their structure which has not become more or less altered; and to + give you an idea of how extensive these alterations are, I have here some + very good skeletons, for which I am indebted to my friend, Mr. Tegetmeier, + a great authority in these matters; by means of which, if you examine them + by-and-by, you will be able to see the enormous difference in their bony + structures. + </p> + <p> + I had the privilege, some time ago, of access to some important MSS. of + Mr. Darwin, who, I may tell you, has taken very great pains and spent much + valuable time and attention on the investigation of these variations, and + getting together all the facts that bear upon them. I obtained from these + MSS. the following summary of the differences between the domestic breeds + of pigeons; that is to say, a notification of the various points in which + their organization differs. In the first place, the back of the skull may + differ a good deal, and the development of the bones of the face may vary + a great deal; the back varies a good deal; the shape of the lower jaw + varies; the tongue varies very greatly, not only in correlation to the + length and size of the beak, but it seems also to have a kind of + independent variation of its own. Then the amount of naked skin round the + eyes, and at the base of the beak, may vary enormously; so may the length + of the eyelids, the shape of the nostrils, and the length of the neck. I + have already noticed the habit of blowing out the gullet, so remarkable in + the Pouter, and comparatively so in the others. There are great + differences, too, in the size of the female and the male, the shape of the + body, the number and width of the processes of the ribs, the development + of the ribs, and the size, shape, and development of the breastbone. We + may notice, too,—and I mention the fact because it has been disputed + by what is assumed to be high authority,—the variation in the number + of the sacral vertebrae. The number of these varies from eleven to + fourteen, and that without any diminution in the number of the vertebrae + of the back or of the tail. Then the number and position of the + tail-feathers may vary enormously, and so may the number of the primary + and secondary feathers of the wings. Again, the length of the feet and of + the beak,—although they have no relation to each other, yet appear + to go together,—that is, you have a long beak wherever you have long + feet. There are differences also in the periods of the acquirement of the + perfect plumage,—the size and shape of the eggs,—the nature of + flight, and the powers of flight,—so-called "homing" birds having + enormous flying powers; <a href="#linknote-1" name="linknoteref-1" + id="linknoteref-1"><small>1</small></a> while, on the other hand, the + little Tumbler is so called because of its extraordinary faculty of + turning head over heels in the air, instead of pursuing a direct course. + And, lastly, the dispositions and voices of the birds may vary. Thus the + case of the pigeons shows you that there is hardly a single particular,—whether + of instinct, or habit, or bony structure, or of plumage,—of either + the internal economy or the external shape, in which some variation or + change may not take place, which, by selective breeding, may become + perpetuated, and form the foundation of, and give rise to, a new race. + </p> + <p> + If you carry in your mind's eye these four varieties of pigeons, you will + bear with you as good a notion as you can have, perhaps, of the enormous + extent to which a deviation from a primitive type may be carried by means + of this process of selective breeding. + </p> + <p> + <a name="linknote-1" id="linknote-1"> + <!-- Note --></a> + </p> + <p class="foot"> + 1 (<a href="#linknoteref-1">return</a>)<br /> [ The "Carrier," I learn from + Mr. Tegetmeier, does not 'carry'; a high-bred bird of this breed being but + a poor flier. The birds which fly long distances, and come home,—"homing" + birds,—and are consequently used as carriers, are not "carriers" in + the fancy sense.] + </p> + <p> + <br /><br /><br /><br /> + </p> +<pre xml:space="preserve"> + + + + + +End of the Project Gutenberg EBook of The Perpetuation Of Living Beings, +Hereditary Transmission And Variation, by Thomas H. Huxley + +*** END OF THIS PROJECT GUTENBERG EBOOK HEREDITARY TRANSMISSION *** + +***** This file should be named 2924-h.htm or 2924-h.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/2/9/2/2924/ + +Produced by Amy E. Zelmer, and David Widger + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere 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 + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH F3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + + +</pre> + </body> +</html> diff --git a/2924.txt b/2924.txt new file mode 100644 index 0000000..dff9aba --- /dev/null +++ b/2924.txt @@ -0,0 +1,983 @@ +The Project Gutenberg EBook of The Perpetuation Of Living Beings, +Hereditary Transmission And Variation, by Thomas H. Huxley + +This eBook is for the use of anyone anywhere 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 + + +Title: The Perpetuation Of Living Beings, Hereditary Transmission And Variation + Lecture IV. (of VI.), Lectures To Working Men, at the + Museum of Practical Geology, 1863, On Darwin's work: "Origin + of Species". + +Author: Thomas H. Huxley + +Posting Date: January 4, 2009 [EBook #2924] +Release Date: November, 2001 + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK HEREDITARY TRANSMISSION *** + + + + +Produced by Amy E. Zelmer + + + + + +THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND VARIATION + +By Thomas Henry Huxley + + + + +The inquiry which we undertook, at our last meeting, into the state of +our knowledge of the causes of the phenomena of organic nature,--of the +past and of the present,--resolved itself into two subsidiary inquiries: +the first was, whether we know anything, either historically or +experimentally, of the mode of origin of living beings; the second +subsidiary inquiry was, whether, granting the origin, we know anything +about the perpetuation and modifications of the forms of organic beings. +The reply which I had to give to the first question was altogether +negative, and the chief result of my last lecture was, that, neither +historically nor experimentally, do we at present know anything +whatsoever about the origin of living forms. We saw that, historically, +we are not likely to know anything about it, although we may perhaps +learn something experimentally; but that at present we are an enormous +distance from the goal I indicated. + +I now, then, take up the next question, What do we know of the +reproduction, the perpetuation, and the modifications of the forms +of living beings, supposing that we have put the question as to their +origination on one side, and have assumed that at present the causes of +their origination are beyond us, and that we know nothing about them? +Upon this question the state of our knowledge is extremely different; it +is exceedingly large, and, if not complete, our experience is certainly +most extensive. It would be impossible to lay it all before you, and the +most I can do, or need do to-night, is to take up the principal points +and put them before you with such prominence as may subserve the +purposes of our present argument. + +The method of the perpetuation of organic beings is of two kinds,--the +asexual and the sexual. In the first the perpetuation takes place from +and by a particular act of an individual organism, which sometimes may +not be classed as belonging to any sex at all. In the second case, it is +in consequence of the mutual action and interaction of certain portions +of the organisms of usually two distinct individuals,--the male and the +female. The cases of asexual perpetuation are by no means so common as +the cases of sexual perpetuation; and they are by no means so common in +the animal as in the vegetable world. You are all probably familiar with +the fact, as a matter of experience, that you can propagate plants +by means of what are called "cuttings;" for example, that by taking a +cutting from a geranium plant, and rearing it properly, by supplying it +with light and warmth and nourishment from the earth, it grows up +and takes the form of its parent, having all the properties and +peculiarities of the original plant. + +Sometimes this process, which the gardener performs artificially, takes +place naturally; that is to say, a little bulb, or portion of the plant, +detaches itself, drops off, and becomes capable of growing as a separate +thing. That is the case with many bulbous plants, which throw off in +this way secondary bulbs, which are lodged in the ground and become +developed into plants. This is an asexual process, and from it results +the repetition or reproduction of the form of the original being from +which the bulb proceeds. + +Among animals the same thing takes place. Among the lower forms of +animal life, the infusorial animalculae we have already spoken of throw +off certain portions, or break themselves up in various directions, +sometimes transversely or sometimes longitudinally; or they may give off +buds, which detach themselves and develop into their proper forms. There +is the common fresh-water Polype, for instance, which multiplies itself +in this way. Just in the same way as the gardener is able to multiply +and reproduce the peculiarities and characters of particular plants +by means of cuttings, so can the physiological experimentalist--as was +shown by the Abbe Trembley many years ago--so can he do the same thing +with many of the lower forms of animal life. M. de Trembley showed that +you could take a polype and cut it into two, or four, or many pieces, +mutilating it in all directions, and the pieces would still grow up +and reproduce completely the original form of the animal. These are +all cases of asexual multiplication, and there are other instances, +and still more extraordinary ones, in which this process takes place +naturally, in a more hidden, a more recondite kind of way. You are all +of you familiar with those little green insects, the 'Aphis' or blight, +as it is called. These little animals, during a very considerable part +of their existence, multiply themselves by means of a kind of internal +budding, the buds being developed into essentially asexual animals, +which are neither male nor female; they become converted into young +'Aphides', which repeat the process, and their offspring after them, +and so on again; you may go on for nine or ten, or even twenty or more +successions; and there is no very good reason to say how soon it might +terminate, or how long it might not go on if the proper conditions of +warmth and nourishment were kept up. + +Sexual reproduction is quite a distinct matter. Here, in all these +cases, what is required is the detachment of two portions of the +parental organisms, which portions we know as the egg and the +spermatozoon. In plants it is the ovule and the pollen-grain, as in +the flowering plants, or the ovule and the antherozooid, as in the +flowerless. Among all forms of animal life, the spermatozoa proceed from +the male sex, and the egg is the product of the female. Now, what is +remarkable about this mode of reproduction is this, that the egg by +itself, or the spermatozoa by themselves, are unable to assume the +parental form; but if they be brought into contact with one another, the +effect of the mixture of organic substances proceeding from two sources +appears to confer an altogether new vigour to the mixed product. This +process is brought about, as we all know, by the sexual intercourse of +the two sexes, and is called the act of impregnation. The result of this +act on the part of the male and female is, that the formation of a new +being is set up in the ovule or egg; this ovule or egg soon begins to +be divided and subdivided, and to be fashioned into various complex +organisms, and eventually to develop into the form of one of its +parents, as I explained in the first lecture. These are the processes by +which the perpetuation of organic beings is secured. Why there should be +the two modes--why this re-invigoration should be required on the part +of the female element we do not know; but it is most assuredly the +fact, and it is presumable, that, however long the process of asexual +multiplication could be continued, I say there is good reason to believe +that it would come to an end if a new commencement were not obtained by +a conjunction of the two sexual elements. + +That character which is common to these two distinct processes is +this, that, whether we consider the reproduction, or perpetuation, or +modification of organic beings as they take place asexually, or as they +may take place sexually,--in either case, I say, the offspring has a +constant tendency to assume, speaking generally, the character of the +parent. As I said just now, if you take a slip of a plant, and tend it +with care, it will eventually grow up and develop into a plant like +that from which it had sprung; and this tendency is so strong that, as +gardeners know, this mode of multiplying by means of cuttings is the +only secure mode of propagating very many varieties of plants; the +peculiarity of the primitive stock seems to be better preserved if you +propagate it by means of a slip than if you resort to the sexual mode. + +Again, in experiments upon the lower animals, such as the polype, to +which I have referred, it is most extraordinary that, although cut up +into various pieces, each particular piece will grow up into the form of +the primitive stock; the head, if separated, will reproduce the body +and the tail; and if you cut off the tail, you will find that that will +reproduce the body and all the rest of the members, without in any way +deviating from the plan of the organism from which these portions have +been detached. And so far does this go, that some experimentalists have +carefully examined the lower orders of animals,--among them the +Abbe Spallanzani, who made a number of experiments upon snails and +salamanders,--and have found that they might mutilate them to an +incredible extent; that you might cut off the jaw or the greater part +of the head, or the leg or the tail, and repeat the experiment several +times, perhaps, cutting off the same member again and again; and yet +each of those types would be reproduced according to the primitive type: +nature making no mistake, never putting on a fresh kind of leg, or head, +or tail, but always tending to repeat and to return to the primitive +type. + +It is the same in sexual reproduction: it is a matter of perfectly +common experience, that the tendency on the part of the offspring always +is, speaking broadly, to reproduce the form of the parents. The +proverb has it that the thistle does not bring forth grapes; so, among +ourselves, there is always a likeness, more or less marked and distinct, +between children and their parents. That is a matter of familiar and +ordinary observation. We notice the same thing occurring in the cases +of the domestic animals--dogs, for instance, and their offspring. In +all these cases of propagation and perpetuation, there seems to be +a tendency in the offspring to take the characters of the parental +organisms. To that tendency a special name is given--it is called +'Atavism', it expresses this tendency to revert to the ancestral type, +and comes from the Latin word 'atavus', ancestor. + +Well, this 'Atavism' which I shall speak of, is, as I said before, one +of the most marked and striking tendencies of organic beings; but, side +by side with this hereditary tendency there is an equally distinct and +remarkable tendency to variation. The tendency to reproduce the original +stock has, as it were, its limits, and side by side with it there is a +tendency to vary in certain directions, as if there were two opposing +powers working upon the organic being, one tending to take it in a +straight line, and the other tending to make it diverge from that +straight line, first to one side and then to the other. + +So that you see these two tendencies need not precisely contradict one +another, as the ultimate result may not always be very remote from what +would have been the case if the line had been quite straight. + +This tendency to variation is less marked in that mode of propagation +which takes place asexually; it is in that mode that the minor +characters of animal and vegetable structures are most completely +preserved. Still, it will happen sometimes, that the gardener, when he +has planted a cutting of some favourite plant, will find, contrary to +his expectation, that the slip grows up a little different from the +primitive stock--that it produces flowers of a different colour or make, +or some deviation in one way or another. This is what is called the +'sporting' of plants. + +In animals the phenomena of asexual propagation are so obscure, that +at present we cannot be said to know much about them; but if we turn to +that mode of perpetuation which results from the sexual process, then +we find variation a perfectly constant occurrence, to a certain extent; +and, indeed, I think that a certain amount of variation from the +primitive stock is the necessary result of the method of sexual +propagation itself; for, inasmuch as the thing propagated proceeds from +two organisms of different sexes and different makes and temperaments, +and as the offspring is to be either of one sex or the other, it is +quite clear that it cannot be an exact diagonal of the two, or it would +be of no sex at all; it cannot be an exact intermediate form between +that of each of its parents--it must deviate to one side or the other. +You do not find that the male follows the precise type of the male +parent, nor does the female always inherit the precise characteristics +of the mother,--there is always a proportion of the female character in +the male offspring, and of the male character in the female offspring. +That must be quite plain to all of you who have looked at all +attentively on your own children or those of your neighbours; you will +have noticed how very often it may happen that the son shall exhibit the +maternal type of character, or the daughter possess the characteristics +of the father's family. There are all sorts of intermixtures and +intermediate conditions between the two, where complexion, or beauty, +or fifty other different peculiarities belonging to either side of the +house, are reproduced in other members of the same family. Indeed, it +is sometimes to be remarked in this kind of variation, that the variety +belongs, strictly speaking, to neither of the immediate parents; you +will see a child in a family who is not like either its father or its +mother; but some old person who knew its grandfather or grandmother, or, +it may be, an uncle, or, perhaps, even a more distant relative, will see +a great similarity between the child and one of these. In this way it +constantly happens that the characteristic of some previous member +of the family comes out and is reproduced and recognised in the most +unexpected manner. + +But apart from that matter of general experience, there are some cases +which put that curious mixture in a very clear light. You are aware that +the offspring of the Ass and the Horse, or rather of the he-Ass and the +Mare, is what is called a Mule; and, on the other hand, the offspring +of the Stallion and the she-Ass is what is called a 'Hinny'. I never saw +one myself; but they have been very carefully studied. Now, the +curious thing is this, that although you have the same elements in +the experiment in each case, the offspring is entirely different in +character, according as the male influence comes from the Ass or the +Horse. Where the Ass is the male, as in the case of the Mule, you find +that the head is like that of the Ass, that the ears are long, the +tail is tufted at the end, the feet are small, and the voice is an +unmistakable bray; these are all points of similarity to the Ass; but, +on the other hand, the barrel of the body and the cut of the neck are +much more like those of the Mare. Then, if you look at the Hinny,--the +result of the union of the Stallion and the she-Ass, then you find it is +the Horse that has the predominance; that the head is more like that +of the Horse, the ears are shorter, the legs coarser, and the type is +altogether altered; while the voice, instead of being a bray, is the +ordinary neigh of the Horse. Here, you see, is a most curious thing: you +take exactly the same elements, Ass and Horse, but you combine the sexes +in a different manner, and the result is modified accordingly. You +have in this case, however, a result which is not general and +universal--there is usually an important preponderance, but not always +on the same side. + +Here, then, is one intelligible, and, perhaps, necessary cause of +variation: the fact, that there are two sexes sharing in the production +of the offspring, and that the share taken by each is different and +variable, not only for each combination, but also for different members +of the same family. + +Secondly, there is a variation, to a certain extent--though, in +all probability, the influence of this cause has been very much +exaggerated--but there is no doubt that variation is produced, to a +certain extent, by what are commonly known as external conditions,--such +as temperature, food, warmth, and moisture. In the long run, every +variation depends, in some sense, upon external conditions, seeing that +everything has a cause of its own. I use the term "external conditions" +now in the sense in which it is ordinarily employed: certain it is, that +external conditions have a definite effect. You may take a plant which +has single flowers, and by dealing with the soil, and nourishment, and +so on, you may by-and-by convert single flowers into double flowers, +and make thorns shoot out into branches. You may thicken or make various +modifications in the shape of the fruit. In animals, too, you may +produce analogous changes in this way, as in the case of that deep +bronze colour which persons rarely lose after having passed any length +of time in tropical countries. You may also alter the development of +the muscles very much, by dint of training; all the world knows that +exercise has a great effect in this way; we always expect to find the +arm of a blacksmith hard and wiry, and possessing a large development +of the brachial muscles. No doubt training, which is one of the forms +of external conditions, converts what are originally only instructions, +teachings, into habits, or, in other words, into organizations, to a +great extent; but this second cause of variation cannot be considered +to be by any means a large one. The third cause that I have to mention, +however, is a very extensive one. It is one that, for want of a better +name, has been called "spontaneous variation;" which means that when +we do not know anything about the cause of phenomena, we call it +spontaneous. In the orderly chain of causes and effects in this world, +there are very few things of which it can be said with truth that they +are spontaneous. Certainly not in these physical matters,--in +these there is nothing of the kind,--everything depends on previous +conditions. But when we cannot trace the cause of phenomena, we call +them spontaneous. + +Of these variations, multitudinous as they are, but little is known with +perfect accuracy. I will mention to you some two or three cases, because +they are very remarkable in themselves, and also because I shall want to +use them afterwards. Reaumur, a famous French naturalist, a great +many years ago, in an essay which he wrote upon the art of hatching +chickens,--which was indeed a very curious essay,--had occasion to speak +of variations and monstrosities. One very remarkable case had come under +his notice of a variation in the form of a human member, in the person +of a Maltese, of the name of Gratio Kelleia, who was born with six +fingers upon each hand, and the like number of toes to each of his feet. +That was a case of spontaneous variation. Nobody knows why he was born +with that number of fingers and toes, and as we don't know, we call it a +case of "spontaneous" variation. There is another remarkable case also. +I select these, because they happen to have been observed and noted very +carefully at the time. It frequently happens that a variation occurs, +but the persons who notice it do not take any care in noting down the +particulars, until at length, when inquiries come to be made, the exact +circumstances are forgotten; and hence, multitudinous as may be such +"spontaneous" variations, it is exceedingly difficult to get at the +origin of them. + +The second case is one of which you may find the whole details in the +"Philosophical Transactions" for the year 1813, in a paper communicated +by Colonel Humphrey to the President of the Royal Society,--"On a new +Variety in the Breed of Sheep," giving an account of a very remarkable +breed of sheep, which at one time was well known in the northern states +of America, and which went by the name of the Ancon or the Otter breed +of sheep. In the year 1791, there was a farmer of the name of Seth +Wright in Massachusetts, who had a flock of sheep, consisting of a ram +and, I think, of some twelve or thirteen ewes. Of this flock of ewes, +one at the breeding-time bore a lamb which was very singularly formed; +it had a very long body, very short legs, and those legs were bowed! +I will tell you by-and-by how this singular variation in the breed of +sheep came to be noted, and to have the prominence that it now has. For +the present, I mention only these two cases; but the extent of variation +in the breed of animals is perfectly obvious to any one who has studied +natural history with ordinary attention, or to any person who compares +animals with others of the same kind. It is strictly true that there are +never any two specimens which are exactly alike; however similar, they +will always differ in some certain particular. + +Now let us go back to Atavism,--to the hereditary tendency I spoke +of. What will come of a variation when you breed from it, when Atavism +comes, if I may say so, to intersect variation? The two cases of which +I have mentioned the history, give a most excellent illustration of +what occurs. Gratio Kelleia, the Maltese, married when he was twenty-two +years of age, and, as I suppose there were no six-fingered ladies in +Malta, he married an ordinary five-fingered person. The result of that +marriage was four children; the first, who was christened Salvator, had +six fingers and six toes, like his father; the second was George, who +had five fingers and toes, but one of them was deformed, showing a +tendency to variation; the third was Andre; he had five fingers and five +toes, quite perfect; the fourth was a girl, Marie; she had five fingers +and five toes, but her thumbs were deformed, showing a tendency toward +the sixth. + +These children grew up, and when they came to adult years, they all +married, and of course it happened that they all married five-fingered +and five-toed persons. Now let us see what were the results. Salvator +had four children; they were two boys, a girl, and another boy; the +first two boys and the girl were six-fingered and six-toed like their +grandfather; the fourth boy had only five fingers and five toes. George +had only four children; there were two girls with six fingers and six +toes; there was one girl with six fingers and five toes on the right +side, and five fingers and five toes on the left side, so that she was +half and half. The last, a boy, had five fingers and five toes. The +third, Andre, you will recollect, was perfectly well-formed, and he had +many children whose hands and feet were all regularly developed. Marie, +the last, who, of course, married a man who had only five fingers, had +four children; the first, a boy, was born with six toes, but the other +three were normal. + +Now observe what very extraordinary phenomena are presented here. +You have an accidental variation arising from what you may call a +monstrosity; you have that monstrosity tendency or variation diluted in +the first instance by an admixture with a female of normal construction, +and you would naturally expect that, in the results of such an union, +the monstrosity, if repeated, would be in equal proportion with the +normal type; that is to say, that the children would be half and half, +some taking the peculiarity of the father, and the others being of +the purely normal type of the mother; but you see we have a great +preponderance of the abnormal type. Well, this comes to be mixed once +more with the pure, the normal type, and the abnormal is again produced +in large proportion, notwithstanding the second dilution. Now what would +have happened if these abnormal types had intermarried with each other; +that is to say, suppose the two boys of Salvator had taken it into their +heads to marry their first cousins, the two first girls of George, their +uncle? You will remember that these are all of the abnormal type of +their grandfather. The result would probably have been, that their +offspring would have been in every case a further development of that +abnormal type. You see it is only in the fourth, in the person of +Marie, that the tendency, when it appears but slightly in the second +generation, is washed out in the third, while the progeny of Andre, who +escaped in the first instance, escape altogether. + +We have in this case a good example of nature's tendency to the +perpetuation of a variation. Here it is certainly a variation which +carried with it no use or benefit; and yet you see the tendency to +perpetuation may be so strong, that, notwithstanding a great admixture +of pure blood, the variety continues itself up to the third generation, +which is largely marked with it. In this case, as I have said, there +was no means of the second generation intermarrying with any but +five-fingered persons, and the question naturally suggests itself, What +would have been the result of such marriage? Reaumur narrates this case +only as far as the third generation. Certainly it would have been +an exceedingly curious thing if we could have traced this matter any +further; had the cousins intermarried, a six-fingered variety of the +human race might have been set up. + +To show you that this supposition is by no means an unreasonable one, +let me now point out what took place in the case of Seth Wright's sheep, +where it happened to be a matter of moment to him to obtain a breed +or raise a flock of sheep like that accidental variety that I have +described--and I will tell you why. In that part of Massachusetts where +Seth Wright was living, the fields were separated by fences, and the +sheep, which were very active and robust, would roam abroad, and without +much difficulty jump over these fences into other people's farms. As +a matter of course, this exuberant activity on the part of the +sheep constantly gave rise to all sorts of quarrels, bickerings, and +contentions among the farmers of the neighbourhood; so it occurred to +Seth Wright, who was, like his successors, more or less 'cute, that if +he could get a stock of sheep like those with the bandy legs, they would +not be able to jump over the fences so readily, and he acted upon that +idea. He killed his old ram, and as soon as the young one arrived at +maturity, he bred altogether from it. The result was even more striking +than in the human experiment which I mentioned just now. Colonel +Humphreys testifies that it always happened that the offspring were +either pure Ancons or pure ordinary sheep; that in no case was there +any mixing of the Ancons with the others. In consequence of this, in +the course of a very few years, the farmer was able to get a very +considerable flock of this variety, and a large number of them were +spread throughout Massachusetts. Most unfortunately, however--I suppose +it was because they were so common--nobody took enough notice of them to +preserve their skeletons; and although Colonel Humphreys states that he +sent a skeleton to the President of the Royal Society at the same time +that he forwarded his paper, I am afraid that the variety has entirely +disappeared; for a short time after these sheep had become prevalent in +that district, the Merino sheep were introduced; and as their wool was +much more valuable, and as they were a quiet race of sheep, and showed +no tendency to trespass or jump over fences, the Otter breed of sheep, +the wool of which was inferior to that of the Merino, was gradually +allowed to die out. + +You see that these facts illustrate perfectly well what may be done if +you take care to breed from stocks that are similar to each other. After +having got a variation, if, by crossing a variation with the original +stock, you multiply that variation, and then take care to keep that +variation distinct from the original stock, and make them breed +together,--then you may almost certainly produce a race whose tendency +to continue the variation is exceedingly strong. + +This is what is called "selection"; and it is by exactly the same +process as that by which Seth Wright bred his Ancon sheep, that +our breeds of cattle, dogs, and fowls, are obtained. There are some +possibilities of exception, but still, speaking broadly, I may say that +this is the way in which all our varied races of domestic animals have +arisen; and you must understand that it is not one peculiarity or one +characteristic alone in which animals may vary. There is not a single +peculiarity or characteristic of any kind, bodily or mental, in which +offspring may not vary to a certain extent from the parent and other +animals. + +Among ourselves this is well known. The simplest physical peculiarity is +mostly reproduced. I know a case of a man whose wife has the lobe of +one of her ears a little flattened. An ordinary observer might scarcely +notice it, and yet every one of her children has an approximation to the +same peculiarity to some extent. If you look at the other extreme, too, +the gravest diseases, such as gout, scrofula, and consumption, may be +handed down with just the same certainty and persistence as we noticed +in the perpetuation of the bandy legs of the Ancon sheep. + +However, these facts are best illustrated in animals, and the extent +of the variation, as is well known, is very remarkable in dogs. For +example, there are some dogs very much smaller than others; indeed, the +variation is so enormous that probably the smallest dog would be about +the size of the head of the largest; there are very great variations in +the structural forms not only of the skeleton but also in the shape of +the skull, and in the proportions of the face and the disposition of the +teeth. + +The Pointer, the Retriever, Bulldog, and the Terrier, differ very +greatly, and yet there is every reason to believe that every one +of these races has arisen from the same source,--that all the most +important races have arisen by this selective breeding from accidental +variation. + +A still more striking case of what may be done by selective breeding, +and it is a better case, because there is no chance of that partial +infusion of error to which I alluded, has been studied very carefully by +Mr. Darwin,--the case of the domestic pigeons. I dare say there may +be some among you who may be pigeon 'fanciers', and I wish you to +understand that in approaching the subject, I would speak with all +humility and hesitation, as I regret to say that I am not a pigeon +fancier. I know it is a great art and mystery, and a thing upon which +a man must not speak lightly; but I shall endeavour, as far as +my understanding goes, to give you a summary of the published and +unpublished information which I have gained from Mr. Darwin. + +Among the enormous variety,--I believe there are somewhere about a +hundred and fifty kinds of pigeons,--there are four kinds which may +be selected as representing the extremest divergences of one kind from +another. Their names are the Carrier, the Pouter, the Fantail, and +the Tumbler. In the large diagrams they are each represented in their +relative sizes to each other. This first one is the Carrier; you will +notice this large excrescence on its beak; it has a comparatively small +head; there is a bare space round the eyes; it has a long neck, a very +long beak, very strong legs, large feet, long wings, and so on. The +second one is the Pouter, a very large bird, with very long legs and +beak. It is called the Pouter because it is in the habit of causing its +gullet to swell up by inflating it with air. I should tell you that all +pigeons have a tendency to do this at times, but in the Pouter it is +carried to an enormous extent. The birds appear to be quite proud of +their power of swelling and puffing themselves out in this way; and I +think it is about as droll a sight as you can well see to look at a +cage full of these pigeons puffing and blowing themselves out in this +ridiculous manner. + +The third kind I mentioned--the Fantail--is a small bird, with +exceedingly small legs and a very small beak. It is most curiously +distinguished by the size and extent of its tail, which, instead of +containing twelve feathers, may have many more,--say thirty, or even +more--I believe there are some with as many as forty-two. This bird has +a curious habit of spreading out the feathers of its tail in such a +way that they reach forward, and touch its head; and if this can be +accomplished, I believe it is looked upon as a point of great beauty. + +But here is the last great variety,--the Tumbler; and of that great +variety, one of the principal kinds, and one most prized, is the +specimen represented here--the short-faced Tumbler. Its beak is reduced +to a mere nothing. Just compare the beak of this one and that of the +first one, the Carrier--I believe the orthodox comparison of the head +and beak of a thoroughly well-bred Tumbler is to stick an oat into a +cherry, and that will give you the proper relative proportions of the +head and beak. The feet and legs are exceedingly small, and the bird +appears to be quite a dwarf when placed side by side with this great +Carrier. + +These are differences enough in regard to their external appearance; but +these differences are by no means the whole or even the most important +of the differences which obtain between these birds. There is hardly +a single point of their structure which has not become more or less +altered; and to give you an idea of how extensive these alterations +are, I have here some very good skeletons, for which I am indebted to my +friend, Mr. Tegetmeier, a great authority in these matters; by means +of which, if you examine them by-and-by, you will be able to see the +enormous difference in their bony structures. + +I had the privilege, some time ago, of access to some important MSS. of +Mr. Darwin, who, I may tell you, has taken very great pains and +spent much valuable time and attention on the investigation of these +variations, and getting together all the facts that bear upon them. +I obtained from these MSS. the following summary of the differences +between the domestic breeds of pigeons; that is to say, a notification +of the various points in which their organization differs. In the first +place, the back of the skull may differ a good deal, and the development +of the bones of the face may vary a great deal; the back varies a good +deal; the shape of the lower jaw varies; the tongue varies very greatly, +not only in correlation to the length and size of the beak, but it seems +also to have a kind of independent variation of its own. Then the amount +of naked skin round the eyes, and at the base of the beak, may vary +enormously; so may the length of the eyelids, the shape of the nostrils, +and the length of the neck. I have already noticed the habit of blowing +out the gullet, so remarkable in the Pouter, and comparatively so in the +others. There are great differences, too, in the size of the female and +the male, the shape of the body, the number and width of the processes +of the ribs, the development of the ribs, and the size, shape, and +development of the breastbone. We may notice, too,--and I mention +the fact because it has been disputed by what is assumed to be high +authority,--the variation in the number of the sacral vertebrae. The +number of these varies from eleven to fourteen, and that without any +diminution in the number of the vertebrae of the back or of the tail. +Then the number and position of the tail-feathers may vary enormously, +and so may the number of the primary and secondary feathers of the +wings. Again, the length of the feet and of the beak,--although they +have no relation to each other, yet appear to go together,--that is, you +have a long beak wherever you have long feet. There are differences also +in the periods of the acquirement of the perfect plumage,--the size +and shape of the eggs,--the nature of flight, and the powers of +flight,--so-called "homing" birds having enormous flying powers; [1] +while, on the other hand, the little Tumbler is so called because of its +extraordinary faculty of turning head over heels in the air, instead of +pursuing a direct course. And, lastly, the dispositions and voices of +the birds may vary. Thus the case of the pigeons shows you that there +is hardly a single particular,--whether of instinct, or habit, or +bony structure, or of plumage,--of either the internal economy or the +external shape, in which some variation or change may not take place, +which, by selective breeding, may become perpetuated, and form the +foundation of, and give rise to, a new race. + +[Footnote 1: The "Carrier," I learn from Mr. Tegetmeier, does not +'carry'; a high-bred bird of this breed being but a poor flier. The +birds which fly long distances, and come home,--"homing" birds,--and are +consequently used as carriers, are not "carriers" in the fancy sense.] + +If you carry in your mind's eye these four varieties of pigeons, you +will bear with you as good a notion as you can have, perhaps, of the +enormous extent to which a deviation from a primitive type may be +carried by means of this process of selective breeding. + + + + + +End of the Project Gutenberg EBook of The Perpetuation Of Living Beings, +Hereditary Transmission And Variation, by Thomas H. Huxley + +*** END OF THIS PROJECT GUTENBERG EBOOK HEREDITARY TRANSMISSION *** + +***** This file should be named 2924.txt or 2924.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/2/9/2/2924/ + +Produced by Amy E. Zelmer + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere 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 + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH F3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/2924.zip b/2924.zip Binary files differnew file mode 100644 index 0000000..ef1d011 --- /dev/null +++ b/2924.zip diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..5c63dbf --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #2924 (https://www.gutenberg.org/ebooks/2924) diff --git a/old/thx0410.txt b/old/thx0410.txt new file mode 100644 index 0000000..0b5eefe --- /dev/null +++ b/old/thx0410.txt @@ -0,0 +1,920 @@ +The Project Gutenberg Etext of The Perpetuation of Living Beings +#14 in our series by Thomas Henry Huxley + +Copyright laws are changing all over the world, be sure to check +the laws for your country before redistributing these files!!! + +Please take a look at the important information in this header. +We encourage you to keep this file on your own disk, keeping an +electronic path open for the next readers. + +Please do not remove this. + +This should be the first thing seen when anyone opens the book. +Do not change or edit it without written permission. The words +are carefully chosen to provide users with the information they +need about what they can legally do with the texts. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**Etexts Readable By Both Humans and By Computers, Since 1971** + +*These Etexts Prepared By Hundreds of Volunteers and Donations* + +Information on contacting Project Gutenberg to get Etexts, and +further information is included below. We need your donations. + +Presently, contributions are only being solicited from people in: +Texas, Nevada, Idaho, Montana, Wyoming, Colorado, South Dakota, +Iowa, Indiana, and Vermont. As the requirements for other states +are met, additions to this list will be made and fund raising will +begin in the additional states. These donations should be made to: + +Project Gutenberg Literary Archive Foundation +PMB 113 +1739 University Ave. +Oxford, MS 38655 + + +Title: The Perpetuation of Living Beings + +Author: Thomas H. Huxley + +Release Date: October, 2001 [Etext #XXXX] +[Yes, we are about one year ahead of schedule] + +Edition: 10 + +The Project Gutenberg Etext of The Perpetuation of Living Beings +******This file should be named thx0410.txt or thx0410.zip****** + +Corrected EDITIONS of our etexts get a new NUMBER, thx0411.txt +VERSIONS based on separate sources get new LETTER, thx0410a.txt + +This etext was prepared by Amy E. Zelmer. + +Project Gutenberg Etexts are usually created from multiple editions, +all of which are in the Public Domain in the United States, unless a +copyright notice is included. Therefore, we usually do NOT keep any +of these books in compliance with any particular paper edition. + +We are now trying to release all our books one year in advance +of the official release dates, leaving time for better editing. +Please be encouraged to send us error messages even years after +the official publication date. + +Please note: neither this list nor its contents are final till +midnight of the last day of the month of any such announcement. +The official release date of all Project Gutenberg Etexts is at +Midnight, Central Time, of the last day of the stated month. A +preliminary version may often be posted for suggestion, comment +and editing by those who wish to do so. + +Most people start at our sites at: +http://gutenberg.net +http://promo.net/pg + + +Those of you who want to download any Etext before announcement +can surf to them as follows, and just download by date; this is +also a good way to get them instantly upon announcement, as the +indexes our cataloguers produce obviously take a while after an +announcement goes out in the Project Gutenberg Newsletter. + +http://metalab.unc.edu/pub/docs/books/gutenberg/etext01 +or +ftp://metalab.unc.edu/pub/docs/books/gutenberg/etext01 + +Or /etext00, 99, 98, 97, 96, 95, 94, 93, 92, 92, 91 or 90 + +Just search by the first five letters of the filename you want, +as it appears in our Newsletters. + + +Information about Project Gutenberg (one page) + +We produce about two million dollars for each hour we work. The +time it takes us, a rather conservative estimate, is fifty hours +to get any etext selected, entered, proofread, edited, copyright +searched and analyzed, the copyright letters written, etc. This +projected audience is one hundred million readers. If our value +per text is nominally estimated at one dollar then we produce $2 +million dollars per hour this year as we release fifty new Etext +files per month, or 500 more Etexts in 2000 for a total of 3000+ +If they reach just 1-2% of the world's population then the total +should reach over 300 billion Etexts given away by year's end. + +The Goal of Project Gutenberg is to Give Away One Trillion Etext +Files by December 31, 2001. [10,000 x 100,000,000 = 1 Trillion] +This is ten thousand titles each to one hundred million readers, +which is only about 4% of the present number of computer users. + +At our revised rates of production, we will reach only one-third +of that goal by the end of 2001, or about 3,333 Etexts unless we +manage to get some real funding. + +Something is needed to create a future for Project Gutenberg for +the next 100 years. + +We need your donations more than ever! + +Presently, contributions are only being solicited from people in: +Texas, Nevada, Idaho, Montana, Wyoming, Colorado, South Dakota, +Iowa, Indiana, and Vermont. As the requirements for other states +are met, additions to this list will be made and fund raising will +begin in the additional states. + +All donations should be made to the Project Gutenberg Literary +Archive Foundation and will be tax deductible to the extent +permitted by law. + +Mail to: + +Project Gutenberg Literary Archive Foundation +PMB 113 +1739 University Avenue +Oxford, MS 38655 [USA] + +We are working with the Project Gutenberg Literary Archive +Foundation to build more stable support and ensure the +future of Project Gutenberg. + +We need your donations more than ever! + +You can get up to date donation information at: + +http://www.gutenberg.net/donation.html + + +*** + +You can always email directly to: + +Michael S. Hart <hart@pobox.com> + +hart@pobox.com forwards to hart@prairienet.org and archive.org +if your mail bounces from archive.org, I will still see it, if +it bounces from prairienet.org, better resend later on. . . . + +We would prefer to send you this information by email. + + +Example command-line FTP session: + +ftp metalab.unc.edu +login: anonymous +password: your@login +cd pub/docs/books/gutenberg +cd etext90 through etext99 or etext00 through etext01, etc. +dir [to see files] +get or mget [to get files. . .set bin for zip files] +GET GUTINDEX.?? [to get a year's listing of books, e.g., GUTINDEX.99] +GET GUTINDEX.ALL [to get a listing of ALL books] + + +**The Legal Small Print** + + +(Three Pages) + +***START**THE SMALL PRINT!**FOR PUBLIC DOMAIN ETEXTS**START*** +Why is this "Small Print!" statement here? You know: lawyers. +They tell us you might sue us if there is something wrong with +your copy of this etext, even if you got it for free from +someone other than us, and even if what's wrong is not our +fault. So, among other things, this "Small Print!" statement +disclaims most of our liability to you. It also tells you how +you can distribute copies of this etext if you want to. + +*BEFORE!* YOU USE OR READ THIS ETEXT +By using or reading any part of this PROJECT GUTENBERG-tm +etext, you indicate that you understand, agree to and accept +this "Small Print!" statement. If you do not, you can receive +a refund of the money (if any) you paid for this etext by +sending a request within 30 days of receiving it to the person +you got it from. If you received this etext on a physical +medium (such as a disk), you must return it with your request. + +ABOUT PROJECT GUTENBERG-TM ETEXTS +This PROJECT GUTENBERG-tm etext, like most PROJECT GUTENBERG-tm etexts, +is a "public domain" work distributed by Professor Michael S. Hart +through the Project Gutenberg Association (the "Project"). +Among other things, this means that no one owns a United States copyright +on or for this work, so the Project (and you!) can copy and +distribute it in the United States without permission and +without paying copyright royalties. Special rules, set forth +below, apply if you wish to copy and distribute this etext +under the Project's "PROJECT GUTENBERG" trademark. + +To create these etexts, the Project expends considerable +efforts to identify, transcribe and proofread public domain +works. Despite these efforts, the Project's etexts and any +medium they may be on may contain "Defects". Among other +things, Defects may take the form of incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other +intellectual property infringement, a defective or damaged +disk or other etext medium, a computer virus, or computer +codes that damage or cannot be read by your equipment. + +LIMITED WARRANTY; DISCLAIMER OF DAMAGES +But for the "Right of Replacement or Refund" described below, +[1] the Project (and any other party you may receive this +etext from as a PROJECT GUTENBERG-tm etext) disclaims all +liability to you for damages, costs and expenses, including +legal fees, and [2] YOU HAVE NO REMEDIES FOR NEGLIGENCE OR +UNDER STRICT LIABILITY, OR FOR BREACH OF WARRANTY OR CONTRACT, +INCLUDING BUT NOT LIMITED TO INDIRECT, CONSEQUENTIAL, PUNITIVE +OR INCIDENTAL DAMAGES, EVEN IF YOU GIVE NOTICE OF THE +POSSIBILITY OF SUCH DAMAGES. + +If you discover a Defect in this etext within 90 days of +receiving it, you can receive a refund of the money (if any) +you paid for it by sending an explanatory note within that +time to the person you received it from. If you received it +on a physical medium, you must return it with your note, and +such person may choose to alternatively give you a replacement +copy. If you received it electronically, such person may +choose to alternatively give you a second opportunity to +receive it electronically. + +THIS ETEXT IS OTHERWISE PROVIDED TO YOU "AS-IS". NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, ARE MADE TO YOU AS +TO THE ETEXT OR ANY MEDIUM IT MAY BE ON, INCLUDING BUT NOT +LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A +PARTICULAR PURPOSE. + +Some states do not allow disclaimers of implied warranties or +the exclusion or limitation of consequential damages, so the +above disclaimers and exclusions may not apply to you, and you +may have other legal rights. + +INDEMNITY +You will indemnify and hold the Project, its directors, +officers, members and agents harmless from all liability, cost +and expense, including legal fees, that arise directly or +indirectly from any of the following that you do or cause: +[1] distribution of this etext, [2] alteration, modification, +or addition to the etext, or [3] any Defect. + +DISTRIBUTION UNDER "PROJECT GUTENBERG-tm" +You may distribute copies of this etext electronically, or by +disk, book or any other medium if you either delete this +"Small Print!" and all other references to Project Gutenberg, +or: + +[1] Only give exact copies of it. Among other things, this + requires that you do not remove, alter or modify the + etext or this "small print!" statement. You may however, + if you wish, distribute this etext in machine readable + binary, compressed, mark-up, or proprietary form, + including any form resulting from conversion by word + processing or hypertext software, but only so long as + *EITHER*: + + [*] The etext, when displayed, is clearly readable, and + does *not* contain characters other than those + intended by the author of the work, although tilde + (~), asterisk (*) and underline (_) characters may + be used to convey punctuation intended by the + author, and additional characters may be used to + indicate hypertext links; OR + + [*] The etext may be readily converted by the reader at + no expense into plain ASCII, EBCDIC or equivalent + form by the program that displays the etext (as is + the case, for instance, with most word processors); + OR + + [*] You provide, or agree to also provide on request at + no additional cost, fee or expense, a copy of the + etext in its original plain ASCII form (or in EBCDIC + or other equivalent proprietary form). + +[2] Honor the etext refund and replacement provisions of this + "Small Print!" statement. + +[3] Pay a trademark license fee to the Project of 20% of the + gross profits you derive calculated using the method you + already use to calculate your applicable taxes. If you + don't derive profits, no royalty is due. Royalties are + payable to "Project Gutenberg Literary Archive Foundation" + the 60 days following each date you prepare (or were + legally required to prepare) your annual (or equivalent + periodic) tax return. Please contact us beforehand to + let us know your plans and to work out the details. + +WHAT IF YOU *WANT* TO SEND MONEY EVEN IF YOU DON'T HAVE TO? +The Project gratefully accepts contributions of money, time, +public domain etexts, and royalty free copyright licenses. +If you are interested in contributing scanning equipment or +software or other items, please contact Michael Hart at: +hart@pobox.com + +*END THE SMALL PRINT! FOR PUBLIC DOMAIN ETEXTS*Ver.04.07.00*END* + + + + + +This etext was prepared by Amy E. Zelmer. + + + + + +THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND +VARIATION + +by Thomas Henry Huxley + + + + +The inquiry which we undertook, at our last meeting, into the state of +our knowledge of the causes of the phenomena of organic nature,--of the +past and of the present,--resolved itself into two subsidiary +inquiries: the first was, whether we know anything, either historically +or experimentally, of the mode of origin of living beings; the second +subsidiary inquiry was, whether, granting the origin, we know anything +about the perpetuation and modifications of the forms of organic +beings. The reply which I had to give to the first question was +altogether negative, and the chief result of my last lecture was, that, +neither historically nor experimentally, do we at present know anything +whatsoever about the origin of living forms. We saw that, historically, +we are not likely to know anything about it, although we may perhaps +learn something experimentally; but that at present we are an enormous +distance from the goal I indicated. + +I now, then, take up the next question, What do we know of the +reproduction, the perpetuation, and the modifications of the forms of +living beings, supposing that we have put the question as to their +origination on one side, and have assumed that at present the causes of +their origination are beyond us, and that we know nothing about them? +Upon this question the state of our knowledge is extremely different; +it is exceedingly large, and, if not complete, our experience is +certainly most extensive. It would be impossible to lay it all before +you, and the most I can do, or need do to-night, is to take up the +principal points and put them before you with such prominence as may +subserve the purposes of our present argument. + +The method of the perpetuation of organic beings is of two kinds,--the +asexual and the sexual. In the first the perpetuation takes place from +and by a particular act of an individual organism, which sometimes may +not be classed as belonging to any sex at all. In the second case, it +is in consequence of the mutual action and interaction of certain +portions of the organisms of usually two distinct individuals,--the +male and the female. The cases of asexual perpetuation are by no means +so common as the cases of sexual perpetuation; and they are by no means +so common in the animal as in the vegetable world. You are all +probably familiar with the fact, as a matter of experience, that you +can propagate plants by means of what are called "cuttings;" for +example, that by taking a cutting from a geranium plant, and rearing it +properly, by supplying it with light and warmth and nourishment from +the earth, it grows up and takes the form of its parent, having all the +properties and peculiarities of the original plant. + +Sometimes this process, which the gardener performs artificially, takes +place naturally; that is to say, a little bulb, or portion of the +plant, detaches itself, drops off, and becomes capable of growing as a +separate thing. That is the case with many bulbous plants, which throw +off in this way secondary bulbs, which are lodged in the ground and +become developed into plants. This is an asexual process, and from it +results the repetition or reproduction of the form of the original +being from which the bulb proceeds. + +Among animals the same thing takes place. Among the lower forms of +animal life, the infusorial animalculae we have already spoken of throw +off certain portions, or break themselves up in various directions, +sometimes transversely or sometimes longitudinally; or they may give +off buds, which detach themselves and develop into their proper forms. +There is the common fresh-water Polype, for instance, which multiplies +itself in this way. Just in the same way as the gardener is able to +multiply and reproduce the peculiarities and characters of particular +plants by means of cuttings, so can the physiological +experimentalist--as was shown by the Abbe Trembley many years ago--so +can he do the same thing with many of the lower forms of animal life. +M. de Trembley showed that you could take a polype and cut it into two, +or four, or many pieces, mutilating it in all directions, and the pieces +would still grow up and reproduce completely the original form of the +animal. These are all cases of asexual multiplication, and there are +other instances, and still more extraordinary ones, in which this +process takes place naturally, in a more hidden, a more recondite kind +of way. You are all of you familiar with those little green insects, +the 'Aphis' or blight, as it is called. These little animals, during a +very considerable part of their existence, multiply themselves by means +of a kind of internal budding, the buds being developed into +essentially asexual animals, which are neither male nor female; they +become converted into young 'Aphides', which repeat the process, and +their offspring after them, and so on again; you may go on for nine or +ten, or even twenty or more successions; and there is no very good +reason to say how soon it might terminate, or how long it might not go +on if the proper conditions of warmth and nourishment were kept up. + +Sexual reproduction is quite a distinct matter. Here, in all these +cases, what is required is the detachment of two portions of the +parental organisms, which portions we know as the egg and the +spermatozoon. In plants it is the ovule and the pollen-grain, as in the +flowering plants, or the ovule and the antherozooid, as in the +flowerless. Among all forms of animal life, the spermatozoa proceed +from the male sex, and the egg is the product of the female. Now, what +is remarkable about this mode of reproduction is this, that the egg by +itself, or the spermatozoa by themselves, are unable to assume the +parental form; but if they be brought into contact with one another, +the effect of the mixture of organic substances proceeding from two +sources appears to confer an altogether new vigour to the mixed product. +This process is brought about, as we all know, by the sexual +intercourse of the two sexes, and is called the act of impregnation. +The result of this act on the part of the male and female is, that the +formation of a new being is set up in the ovule or egg; this ovule or +egg soon begins to be divided and subdivided, and to be fashioned into +various complex organisms, and eventually to develop into the form of +one of its parents, as I explained in the first lecture. These are the +processes by which the perpetuation of organic beings is secured. Why +there should be the two modes--why this re-invigoration should be +required on the part of the female element we do not know; but it is +most assuredly the fact, and it is presumable, that, however long the +process of asexual multiplication could be continued, I say there is +good reason to believe that it would come to an end if a new +commencement were not obtained by a conjunction of the two sexual +elements. + +That character which is common to these two distinct processes is this, +that, whether we consider the reproduction, or perpetuation, or +modification of organic beings as they take place asexually, or as they +may take place sexually,--in either case, I say, the offspring has a +constant tendency to assume, speaking generally, the character of the +parent. As I said just now, if you take a slip of a plant, and tend it +with care, it will eventually grow up and develop into a plant like +that from which it had sprung; and this tendency is so strong that, as +gardeners know, this mode of multiplying by means of cuttings is the +only secure mode of propagating very many varieties of plants; the +peculiarity of the primitive stock seems to be better preserved if you +propagate it by means of a slip than if you resort to the sexual mode. + +Again, in experiments upon the lower animals, such as the polype, to +which I have referred, it is most extraordinary that, although cut up +into various pieces, each particular piece will grow up into the form +of the primitive stock; the head, if separated, will reproduce the body +and the tail; and if you cut off the tail, you will find that that will +reproduce the body and all the rest of the members, without in any way +deviating from the plan of the organism from which these portions have +been detached. And so far does this go, that some experimentalists +have carefully examined the lower orders of animals,--among them the +Abbe Spallanzani, who made a number of experiments upon snails and +salamanders,--and have found that they might mutilate them to an +incredible extent; that you might cut off the jaw or the greater part of +the head, or the leg or the tail, and repeat the experiment several +times, perhaps, cutting off the same member again and again; and yet +each of those types would be reproduced according to the primitive +type: nature making no mistake, never putting on a fresh kind of leg, or +head, or tail, but always tending to repeat and to return to the +primitive type. + +It is the same in sexual reproduction: it is a matter of perfectly +common experience, that the tendency on the part of the offspring +always is, speaking broadly, to reproduce the form of the parents. The +proverb has it that the thistle does not bring forth grapes; so, among +ourselves, there is always a likeness, more or less marked and +distinct, between children and their parents. That is a matter of +familiar and ordinary observation. We notice the same thing occurring +in the cases of the domestic animals--dogs, for instance, and their +offspring. In all these cases of propagation and perpetuation, there +seems to be a tendency in the offspring to take the characters of the +parental organisms. To that tendency a special name is given-- it is +called 'Atavism', it expresses this tendency to revert to the ancestral +type, and comes from the Latin word 'atavus', ancestor. + +Well, this 'Atavism' which I shall speak of, is, as I said before, one +of the most marked and striking tendencies of organic beings; but, side +by side with this hereditary tendency there is an equally distinct and +remarkable tendency to variation. The tendency to reproduce the +original stock has, as it were, its limits, and side by side with it +there is a tendency to vary in certain directions, as if there were two +opposing powers working upon the organic being, one tending to take it +in a straight line, and the other tending to make it diverge from that +straight line, first to one side and then to the other. + +So that you see these two tendencies need not precisely contradict one +another, as the ultimate result may not always be very remote from what +would have been the case if the line had been quite straight. + +This tendency to variation is less marked in that mode of propagation +which takes place asexually; it is in that mode that the minor +characters of animal and vegetable structures are most completely +preserved. Still, it will happen sometimes, that the gardener, when he +has planted a cutting of some favourite plant, will find, contrary to +his expectation, that the slip grows up a little different from the +primitive stock--that it produces flowers of a different colour or +make, or some deviation in one way or another. This is what is called +the 'sporting' of plants. + +In animals the phenomena of asexual propagation are so obscure, that at +present we cannot be said to know much about them; but if we turn to +that mode of perpetuation which results from the sexual process, then +we find variation a perfectly constant occurrence, to a certain extent; +and, indeed, I think that a certain amount of variation from the +primitive stock is the necessary result of the method of sexual +propagation itself; for, inasmuch as the thing propagated proceeds from +two organisms of different sexes and different makes and temperaments, +and as the offspring is to be either of one sex or the other, it is +quite clear that it cannot be an exact diagonal of the two, or it would +be of no sex at all; it cannot be an exact intermediate form between +that of each of its parents--it must deviate to one side or the other. +You do not find that the male follows the precise type of the male +parent, nor does the female always inherit the precise characteristics +of the mother,--there is always a proportion of the female character in +the male offspring, and of the male character in the female offspring. +That must be quite plain to all of you who have looked at all +attentively on your own children or those of your neighbours; you will +have noticed how very often it may happen that the son shall exhibit +the maternal type of character, or the daughter possess the +characteristics of the father's family. There are all sorts of +intermixtures and intermediate conditions between the two, where +complexion, or beauty, or fifty other different peculiarities belonging +to either side of the house, are reproduced in other members of the +same family. Indeed, it is sometimes to be remarked in this kind of +variation, that the variety belongs, strictly speaking, to neither of +the immediate parents; you will see a child in a family who is not like +either its father or its mother; but some old person who knew its +grandfather or grandmother, or, it may be, an uncle, or, perhaps, even +a more distant relative, will see a great similarity between the child +and one of these. In this way it constantly happens that the +characteristic of some previous member of the family comes out and is +reproduced and recognised in the most unexpected manner. + +But apart from that matter of general experience, there are some cases +which put that curious mixture in a very clear light. You are aware +that the offspring of the Ass and the Horse, or rather of the he-Ass +and the Mare, is what is called a Mule; and, on the other hand, the +offspring of the Stallion and the she-Ass is what is called a 'Hinny'. +I never saw one myself; but they have been very carefully studied. Now, +the curious thing is this, that although you have the same elements in +the experiment in each case, the offspring is entirely different in +character, according as the male influence comes from the Ass or the +Horse. Where the Ass is the male, as in the case of the Mule, you find +that the head is like that of the Ass, that the ears are long, the tail +is tufted at the end, the feet are small, and the voice is an +unmistakable bray; these are all points of similarity to the Ass; but, +on the other hand, the barrel of the body and the cut of the neck are +much more like those of the Mare. Then, if you look at the Hinny,--the +result of the union of the Stallion and the she-Ass, then you find it is +the Horse that has the predominance; that the head is more like that of +the Horse, the ears are shorter, the legs coarser, and the type is +altogether altered; while the voice, instead of being a bray, is the +ordinary neigh of the Horse. Here, you see, is a most curious thing: +you take exactly the same elements, Ass and Horse, but you combine the +sexes in a different manner, and the result is modified accordingly. +You have in this case, however, a result which is not general and +universal--there is usually an important preponderance, but not always +on the same side. + +Here, then, is one intelligible, and, perhaps, necessary cause of +variation: the fact, that there are two sexes sharing in the production +of the offspring, and that the share taken by each is different and +variable, not only for each combination, but also for different members +of the same family. + +Secondly, there is a variation, to a certain extent--though, in all +probability, the influence of this cause has been very much +exaggerated--but there is no doubt that variation is produced, to a +certain extent, by what are commonly known as external conditions,--such +as temperature, food, warmth, and moisture. In the long run, every +variation depends, in some sense, upon external conditions, seeing that +everything has a cause of its own. I use the term "external +conditions" now in the sense in which it is ordinarily employed: certain +it is, that external conditions have a definite effect. You may take a +plant which has single flowers, and by dealing with the soil, and +nourishment, and so on, you may by-and-by convert single flowers into +double flowers, and make thorns shoot out into branches. You may +thicken or make various modifications in the shape of the fruit. In +animals, too, you may produce analogous changes in this way, as in the +case of that deep bronze colour which persons rarely lose after having +passed any length of time in tropical countries. You may also alter +the development of the muscles very much, by dint of training; all the +world knows that exercise has a great effect in this way; we always +expect to find the arm of a blacksmith hard and wiry, and possessing a +large development of the brachial muscles. No doubt training, which is +one of the forms of external conditions, converts what are originally +only instructions, teachings, into habits, or, in other words, into +organizations, to a great extent; but this second cause of variation +cannot be considered to be by any means a large one. The third cause +that I have to mention, however, is a very extensive one. It is one +that, for want of a better name, has been called "spontaneous +variation;" which means that when we do not know anything about the +cause of phenomena, we call it spontaneous. In the orderly chain of +causes and effects in this world, there are very few things of which it +can be said with truth that they are spontaneous. Certainly not in +these physical matters,--in these there is nothing of the +kind,--everything depends on previous conditions. But when we cannot +trace the cause of phenomena, we call them spontaneous. + +Of these variations, multitudinous as they are, but little is known with +perfect accuracy. I will mention to you some two or three cases, +because they are very remarkable in themselves, and also because I +shall want to use them afterwards. Reaumur, a famous French naturalist, +a great many years ago, in an essay which he wrote upon the art of +hatching chickens,--which was indeed a very curious essay,--had +occasion to speak of variations and monstrosities. One very remarkable +case had come under his notice of a variation in the form of a human +member, in the person of a Maltese, of the name of Gratio Kelleia, who +was born with six fingers upon each hand, and the like number of toes +to each of his feet. That was a case of spontaneous variation. Nobody +knows why he was born with that number of fingers and toes, and as we +don't know, we call it a case of "spontaneous" variation. There is +another remarkable case also. I select these, because they happen to +have been observed and noted very carefully at the time. It frequently +happens that a variation occurs, but the persons who notice it do not +take any care in noting down the particulars, until at length, when +inquiries come to be made, the exact circumstances are forgotten; and +hence, multitudinous as may be such "spontaneous" variations, it is +exceedingly difficult to get at the origin of them. + +The second case is one of which you may find the whole details in the +"Philosophical Transactions" for the year 1813, in a paper communicated +by Colonel Humphrey to the President of the Royal Society,--"On a new +Variety in the Breed of Sheep," giving an account of a very remarkable +breed of sheep, which at one time was well known in the northern states +of America, and which went by the name of the Ancon or the Otter breed +of sheep. In the year 1791, there was a farmer of the name of Seth +Wright in Massachusetts, who had a flock of sheep, consisting of a ram +and, I think, of some twelve or thirteen ewes. Of this flock of ewes, +one at the breeding-time bore a lamb which was very singularly formed; +it had a very long body, very short legs, and those legs were bowed! I +will tell you by-and-by how this singular variation in the breed of +sheep came to be noted, and to have the prominence that it now has. For +the present, I mention only these two cases; but the extent of variation +in the breed of animals is perfectly obvious to any one who has studied +natural history with ordinary attention, or to any person who compares +animals with others of the same kind. It is strictly true that there +are never any two specimens which are exactly alike; however similar, +they will always differ in some certain particular. + +Now let us go back to Atavism,--to the hereditary tendency I spoke of. +What will come of a variation when you breed from it, when Atavism +comes, if I may say so, to intersect variation? The two cases of which +I have mentioned the history, give a most excellent illustration of +what occurs. Gratio Kelleia, the Maltese, married when he was +twenty-two years of age, and, as I suppose there were no six-fingered +ladies in Malta, he married an ordinary five-fingered person. The +result of that marriage was four children; the first, who was christened +Salvator, had six fingers and six toes, like his father; the second was +George, who had five fingers and toes, but one of them was deformed, +showing a tendency to variation; the third was Andre; he had five +fingers and five toes, quite perfect; the fourth was a girl, Marie; she +had five fingers and five toes, but her thumbs were deformed, showing a +tendency toward the sixth. + +These children grew up, and when they came to adult years, they all +married, and of course it happened that they all married five-fingered +and five-toed persons. Now let us see what were the results. Salvator +had four children; they were two boys, a girl, and another boy; the +first two boys and the girl were six-fingered and six-toed like their +grandfather; the fourth boy had only five fingers and five toes. George +had only four children; there were two girls with six fingers and six +toes; there was one girl with six fingers and five toes on the right +side, and five fingers and five toes on the left side, so that she was +half and half. The last, a boy, had five fingers and five toes. The +third, Andre, you will recollect, was perfectly well-formed, and he had +many children whose hands and feet were all regularly developed. Marie, +the last, who, of course, married a man who had only five fingers, had +four children; the first, a boy, was born with six toes, but the other +three were normal. + +Now observe what very extraordinary phenomena are presented here. You +have an accidental variation arising from what you may call a +monstrosity; you have that monstrosity tendency or variation diluted in +the first instance by an admixture with a female of normal construction, +and you would naturally expect that, in the results of such an union, +the monstrosity, if repeated, would be in equal proportion with the +normal type; that is to say, that the children would be half and half, +some taking the peculiarity of the father, and the others being of the +purely normal type of the mother; but you see we have a great +preponderance of the abnormal type. Well, this comes to be mixed once +more with the pure, the normal type, and the abnormal is again produced +in large proportion, notwithstanding the second dilution. Now what +would have happened if these abnormal types had intermarried with each +other; that is to say, suppose the two boys of Salvator had taken it +into their heads to marry their first cousins, the two first girls of +George, their uncle? You will remember that these are all of the +abnormal type of their grandfather. The result would probably have +been, that their offspring would have been in every case a further +development of that abnormal type. You see it is only in the fourth, +in the person of Marie, that the tendency, when it appears but slightly +in the second generation, is washed out in the third, while the progeny +of Andre, who escaped in the first instance, escape altogether. + +We have in this case a good example of nature's tendency to the +perpetuation of a variation. Here it is certainly a variation which +carried with it no use or benefit; and yet you see the tendency to +perpetuation may be so strong, that, notwithstanding a great admixture +of pure blood, the variety continues itself up to the third generation, +which is largely marked with it. In this case, as I have said, there +was no means of the second generation intermarrying with any but +five-fingered persons, and the question naturally suggests itself, What +would have been the result of such marriage? Reaumur narrates this +case only as far as the third generation. Certainly it would have been +an exceedingly curious thing if we could have traced this matter any +further; had the cousins intermarried, a six-fingered variety of the +human race might have been set up. + +To show you that this supposition is by no means an unreasonable one, +let me now point out what took place in the case of Seth Wright's +sheep, where it happened to be a matter of moment to him to obtain a +breed or raise a flock of sheep like that accidental variety that I +have described--and I will tell you why. In that part of Massachusetts +where Seth Wright was living, the fields were separated by fences, and +the sheep, which were very active and robust, would roam abroad, and +without much difficulty jump over these fences into other people's +farms. As a matter of course, this exuberant activity on the part of +the sheep constantly gave rise to all sorts of quarrels, bickerings, +and contentions among the farmers of the neighbourhood; so it occurred +to Seth Wright, who was, like his successors, more or less 'cute, that +if he could get a stock of sheep like those with the bandy legs, they +would not be able to jump over the fences so readily, and he acted upon +that idea. He killed his old ram, and as soon as the young one arrived +at maturity, he bred altogether from it. The result was even more +striking than in the human experiment which I mentioned just now. +Colonel Humphreys testifies that it always happened that the offspring +were either pure Ancons or pure ordinary sheep; that in no case was +there any mixing of the Ancons with the others. In consequence of +this, in the course of a very few years, the farmer was able to get a +very considerable flock of this variety, and a large number of them +were spread throughout Massachusetts. Most unfortunately, however--I +suppose it was because they were so common--nobody took enough notice +of them to preserve their skeletons; and although Colonel Humphreys +states that he sent a skeleton to the President of the Royal Society at +the same time that he forwarded his paper, I am afraid that the variety +has entirely disappeared; for a short time after these sheep had become +prevalent in that district, the Merino sheep were introduced; and as +their wool was much more valuable, and as they were a quiet race of +sheep, and showed no tendency to trespass or jump over fences, the +Otter breed of sheep, the wool of which was inferior to that of the +Merino, was gradually allowed to die out. + +You see that these facts illustrate perfectly well what may be done if +you take care to breed from stocks that are similar to each other. +After having got a variation, if, by crossing a variation with the +original stock, you multiply that variation, and then take care to keep +that variation distinct from the original stock, and make them breed +together,--then you may almost certainly produce a race whose tendency +to continue the variation is exceedingly strong. + +This is what is called "selection"; and it is by exactly the same +process as that by which Seth Wright bred his Ancon sheep, that our +breeds of cattle, dogs, and fowls, are obtained. There are some +possibilities of exception, but still, speaking broadly, I may say that +this is the way in which all our varied races of domestic animals have +arisen; and you must understand that it is not one peculiarity or one +characteristic alone in which animals may vary. There is not a single +peculiarity or characteristic of any kind, bodily or mental, in which +offspring may not vary to a certain extent from the parent and other +animals. + +Among ourselves this is well known. The simplest physical peculiarity +is mostly reproduced. I know a case of a man whose wife has the lobe of +one of her ears a little flattened. An ordinary observer might +scarcely notice it, and yet every one of her children has an +approximation to the same peculiarity to some extent. If you look at +the other extreme, too, the gravest diseases, such as gout, scrofula, +and consumption, may be handed down with just the same certainty and +persistence as we noticed in the perpetuation of the bandy legs of the +Ancon sheep. + +However, these facts are best illustrated in animals, and the extent of +the variation, as is well known, is very remarkable in dogs. For +example, there are some dogs very much smaller than others; indeed, the +variation is so enormous that probably the smallest dog would be about +the size of the head of the largest; there are very great variations in +the structural forms not only of the skeleton but also in the shape of +the skull, and in the proportions of the face and the disposition of +the teeth. + +The Pointer, the Retriever, Bulldog, and the Terrier, differ very +greatly, and yet there is every reason to believe that every one of +these races has arisen from the same source,--that all the most +important races have arisen by this selective breeding from accidental +variation. + +A still more striking case of what may be done by selective breeding, +and it is a better case, because there is no chance of that partial +infusion of error to which I alluded, has been studied very carefully +by Mr. Darwin,--the case of the domestic pigeons. I dare say there may +be some among you who may be pigeon 'fanciers', and I wish you to +understand that in approaching the subject, I would speak with all +humility and hesitation, as I regret to say that I am not a pigeon +fancier. I know it is a great art and mystery, and a thing upon which a +man must not speak lightly; but I shall endeavour, as far as my +understanding goes, to give you a summary of the published and +unpublished information which I have gained from Mr. Darwin. + +Among the enormous variety,--I believe there are somewhere about a +hundred and fifty kinds of pigeons,--there are four kinds which may be +selected as representing the extremest divergences of one kind from +another. Their names are the Carrier, the Pouter, the Fantail, and the +Tumbler. In the large diagrams they are each represented in their +relative sizes to each other. This first one is the Carrier; you will +notice this large excrescence on its beak; it has a comparatively small +head; there is a bare space round the eyes; it has a long neck, a very +long beak, very strong legs, large feet, long wings, and so on. The +second one is the Pouter, a very large bird, with very long legs and +beak. It is called the Pouter because it is in the habit of causing +its gullet to swell up by inflating it with air. I should tell you that +all pigeons have a tendency to do this at times, but in the Pouter it +is carried to an enormous extent. The birds appear to be quite proud +of their power of swelling and puffing themselves out in this way; and +I think it is about as droll a sight as you can well see to look at a +cage full of these pigeons puffing and blowing themselves out in this +ridiculous manner. + +The third kind I mentioned--the Fantail--is a small bird, with +exceedingly small legs and a very small beak. It is most curiously +distinguished by the size and extent of its tail, which, instead of +containing twelve feathers, may have many more,--say thirty, or even +more--I believe there are some with as many as forty-two. This bird +has a curious habit of spreading out the feathers of its tail in such a +way that they reach forward, and touch its head; and if this can be +accomplished, I believe it is looked upon as a point of great beauty. + +But here is the last great variety,--the Tumbler; and of that great +variety, one of the principal kinds, and one most prized, is the +specimen represented here--the short-faced Tumbler. Its beak is +reduced to a mere nothing. Just compare the beak of this one and that +of the first one, the Carrier--I believe the orthodox comparison of the +head and beak of a thoroughly well-bred Tumbler is to stick an oat into +a cherry, and that will give you the proper relative proportions of the +head and beak. The feet and legs are exceedingly small, and the bird +appears to be quite a dwarf when placed side by side with this great +Carrier. + +These are differences enough in regard to their external appearance; but +these differences are by no means the whole or even the most important +of the differences which obtain between these birds. There is hardly a +single point of their structure which has not become more or less +altered; and to give you an idea of how extensive these alterations are, +I have here some very good skeletons, for which I am indebted to my +friend, Mr. Tegetmeier, a great authority in these matters; by means of +which, if you examine them by-and-by, you will be able to see the +enormous difference in their bony structures. + +I had the privilege, some time ago, of access to some important MSS. of +Mr. Darwin, who, I may tell you, has taken very great pains and spent +much valuable time and attention on the investigation of these +variations, and getting together all the facts that bear upon them. I +obtained from these MSS. the following summary of the differences +between the domestic breeds of pigeons; that is to say, a notification +of the various points in which their organization differs. In the +first place, the back of the skull may differ a good deal, and the +development of the bones of the face may vary a great deal; the back +varies a good deal; the shape of the lower jaw varies; the tongue +varies very greatly, not only in correlation to the length and size of +the beak, but it seems also to have a kind of independent variation of +its own. Then the amount of naked skin round the eyes, and at the base +of the beak, may vary enormously; so may the length of the eyelids, the +shape of the nostrils, and the length of the neck. I have already +noticed the habit of blowing out the gullet, so remarkable in the +Pouter, and comparatively so in the others. There are great +differences, too, in the size of the female and the male, the shape of +the body, the number and width of the processes of the ribs, the +development of the ribs, and the size, shape, and development of the +breastbone. We may notice, too,--and I mention the fact because it has +been disputed by what is assumed to be high authority,--the variation +in the number of the sacral vertebrae. The number of these varies from +eleven to fourteen, and that without any diminution in the number of +the vertebrae of the back or of the tail. Then the number and position +of the tail-feathers may vary enormously, and so may the number of the +primary and secondary feathers of the wings. Again, the length of the +feet and of the beak,--although they have no relation to each other, +yet appear to go together,--that is, you have a long beak wherever you +have long feet. There are differences also in the periods of the +acquirement of the perfect plumage,--the size and shape of the +eggs,--the nature of flight, and the powers of flight,--so-called +"homing" birds having enormous flying powers;* while, on the other +hand, the little Tumbler is so called because of its extraordinary +faculty of turning head over heels in the air, instead of pursuing a +direct course. And, lastly, the dispositions and voices of the birds +may vary. Thus the case of the pigeons shows you that there is hardly +a single particular,--whether of instinct, or habit, or bony structure, +or of plumage,--of either the internal economy or the external shape, +in which some variation or change may not take place, which, by +selective breeding, may become perpetuated, and form the foundation of, +and give rise to, a new race. + + [footnote: The "Carrier," I learn from Mr. Tegetmeier, does + not 'carry'; a high-bred bird of this breed being but a + poor flier. The birds which fly long distances, and come + home,--"homing" birds,--and are consequently used as + carriers, are not "carriers" in the fancy sense.] + +If you carry in your mind's eye these four varieties of pigeons, you +will bear with you as good a notion as you can have, perhaps, of the +enormous extent to which a deviation from a primitive type may be +carried by means of this process of selective breeding. + + + + + +End of The Project Gutenberg Etext of The Perpetuation of Living Beings +by Thomas H. Huxley + diff --git a/old/thx0410.zip b/old/thx0410.zip Binary files differnew file mode 100644 index 0000000..43ef937 --- /dev/null +++ b/old/thx0410.zip |