Initiative in Evolution

The reader, naturalist or layman, can point the moral for himself.

Weismann.

During the period 1894–1899 there was a dramatic proclama­tion on the part of one of the greatest living biologists, which was, in the cosmos of biology, what the Proclama­tion of the Empress-Queen of India was in 1876, and it is not out of place to remind the reader that the fates of the two Imperial utterances have been somewhat different. In 1895 Weismann issued his official statement of doctrine which was to crown the work of his life, an essay on Germinal Selection. From Freyburg in November, 1895, he wrote a preface to his address delivered on September 16th in that year to the International Congress of Zoologists at Leyden. This formed an epoch in biological thought and there lived none so well qualified as Weismann to stand forth as its interpreter. The well-translated, forcible language, and lucid thought leave the reader in no manner of doubt as to his meaning. It took a wider form in his final book on the Evolution Theory, but the germinal and essential thoughts of the latter were contained in the former. From 1895 onwards the praise of Weismann was in all the churches. Probably no modern worker in the fields of heredity and evolution has done so much as Weismann towards raising great issues and removing some ancient misconceptions; but it is one thing to raise great issues and another to solve them. In this he has signally failed, nevertheless biological theory would be the poorer if he had not made the attempt. Reflec­tion, the work of other biologists, and the remorseless hand of time have shaken the edifices then raised. I will here only bring forward a few of the most illuminating passages of the 1895 essay, and then refer to the handling of Weismann’s work by Romanes.

This trenchant essay contains fifty-seven pages, of which reasoning forms the greater part. As to the facts it might well pass for an essay from Professor Poulton’s pen, for Weismann’s special province of insects occupies nearly all the evidence from facts. Outside this highly specialised group there are exactly fifty-three lines, or one and a half pages, which deal with other animal groups, and there are four casual allusions to plants occupying twelve lines in all! In the essay of 1909 on the Selection Theory this treatment of animated life in the world is improved upon and thirteen out of its forty-seven pages refer to animals outside his favourite group of insects. Such exclusive dealing with these little things does not commend the reasoning, at any rate to a neo-Lamarckian; such a circle is too select for him.

Weismann’s Twelve Points.

The most striking remarks from the 1895 essay on germinal selection are:—

1. “The real aim of the present essay is to rehabilitate the principle of selection. If I should succeed in reinstating this principle in its imperilled rights, it would be a source of extreme satisfac­tion to me.”14

2. Speaking of the whole theory of selection he claimed to have found a position “which is necessary to protect it against the many doubts which gathered around it on all sides like so many lowering thunder-clouds.”15 And he speaks on page 26 of “the flood of objections against the theory of selection touching its inability to modify many parts at once.”

Thus Weismann stood forth to defend the crumbling edifice of Darwinism and threw his shining sword into the scales, a scientific Athanasius “contending for our all.” Again is seen a friend of Darwin from another camp than that of Mendel, whose support needs to be received with some caution. Toujours en vedette is a useful rule.

3. Speaking of adaptedness in animated nature he says, “We know of only one natural principle of explana­tion for this fact—that of selection.”16

4. “Germinal selection is the last consequence of the applica­tion of the principle of Malthus to living nature.”17

5. “Without doubt the theory (Germinal Selection) requires that the initial steps of a variation should also have selective value.”18

6. “Something is still wanting in the theory of Darwin and Wallace which it is obligatory on us to discover if we possibly can. We must seek to discover why it happens that useful variations are always present.”19

7. “It is impossible to do without the assump­tion that the useful variations are always present, or that they always exist in a sufficiently large number of individuals for the selective process.”20

8. “Some profound connexions must exist between the utility of a variation and its actual appearance, or the direction of the variation of a part must be determined by utility.”21

9. That “germinal selection performs the same services for the understanding of observed transformations . . . that a heredity of acquired characters would perform without rendering necessary so violent an assump­tion!”22 (Italics mine.)

10. Weismann speaks warmly of Professor Lloyd Morgan for his caution and calmness of judgment but complains of him that he “has not been able to abandon completely the heredity of acquired characters.”23

11. As to passive effects of environment, etc., he says “the Lamarckian principle is here excluded ab initio.”24

12. “It seems to me that a hypothesis of this kind (Lamarckism) has performed its services and must be discarded the moment it is found to be at hopeless variance with the facts.”25

I have only to add here that several years ago I wrote to Weismann drawing his attention to some facts I had observed which seemed to me to be instances of use-inheritance, and I received a reply in polite but brief and Prussian terms to the effect that the facts referred to must be capable of some other interpreta­tion, for the machinery for their transmission did not exist.

Each of these twelve quotations from Weismann’s essay is important from the present point of view, and shows how far neo-Darwinians are likely to promote the greater glory of Darwin, and though more than a quarter of a century elapsed between this essay and his death Weismann was not the man to have repudiated any of these strong statements.

Lighthouse Value.

I hope at this point a small digression is not out of place in order to introduce an aspect of Weismann’s work which is not usually appreciated. A child is aware of the great and lesser lights that rule the day and night, but for modern man these are not sufficient. Accordingly he has invented from immemorial times his oil lamps, rushlights, tallow and wax candles, gas and electric light for the illumina­tion of his streets and houses. Prehistoric man did not seem to need them, as he thought. These useful examples of applied knowledge were obviously brought into use for showing man better where he was going and where to go, what he was doing and what he wished to see. I hope this trite remark may be pardoned, for there is another form of light which suits my purpose of illustrating the aspect of Weismannism referred to above, that is the light of a lighthouse. The ancients in their crude way saw the need for this and as far back as the days of Ptolemy II. a tower to give light was erected on the island of Pharus, off the Egyptian coast, and it was called a pharos. Man found it necessary, as naviga­tion and seafaring advanced, to use this principle more and more, and on headland, sandbank and rugged coast has built noble structures to aid the sailor in his dangerous course. The oldest and finest of these in Great Britain is the Eddystone lighthouse, built first in 1695 by Winstanley and finally by Smeaton in 1756–9. For what reason is a lighthouse built and placed where it is? For the precisely opposite reason to that of the domestic candle. While this shows you where to go and how better to do your immediate business, a lighthouse is for the main purpose of showing a mariner where he should not go. It has no relation to adornment or pleasure. It does not invite you to come in your vessel and admire it. It tells you to go away and avoid the sunken rock or treacherous sands.

I submit here the sugges­tion with all deference, that the final work of Weismann has lighthouse value of a high order, as to the modus operandi of evolution. His greatness as a biologist, his candour and skill in dialectics, have built up a veritable lighthouse which may usefully warn the seeker after the path of evolution that he must turn elsewhere if he would not founder upon a reef of facts.

The two great contributions to evolutionary thought that Weismann has made should be considered separately, the theory of germ-plasm and that of evolution, though the latter seems to be the necessary outcome of the former. But the truth of Weismann’s view of heredity does not of necessity require the error of his theory of evolution.

Romanes on Weismann.

For this study the examina­tion of Weismannism by Romanes published in 1893 is of great value. I need only refer here to the main conclusions of that lucid and learned examina­tion.

Weismann’s work on the germ-plasm in pursuance of a theory of heredity is pronounced by Romanes to have remained up to 1893 substantially unaltered, though largely added to in matters of detail, and at the present time as far as I gather from a study of the more recent literature this theory holds the field or at least a commanding position in it.26 Originally he held that the germ-plasm possessed perpetual continuity since the first origin of life, and absolute stability since the first origin of sexual propaga­tion, but he has shown himself willing to surrender the first postulate, and has himself altered the second. As it stands now it must be admitted that the continuity of the germ-plasm is an interrupted continuity with the appearance of every inherited change; the continuity is theoretical, not actual, and the stability of the germ-plasm is not absolute but of a high degree. We can thus see in the story of this original theory of heredity the lighthouse value of the pharos of Ptolemy II.

It is far otherwise with Weismann’s theory of evolution. Romanes shows that with the removal of its essential postulate the absolute stability of germ-plasm, Weismann’s theory of evolution falls to the ground. He has indeed surrendered much in his later building, his second temple of Solomon, and prominent among these was the claim that the only causes of individual variation and of the origin of species in the uni-cellular organisms are the Lamarckian factors, just as in the multicellular the only cause of these is natural selection. Thus we see standing at the critical date, 1892, the first Eddystone lighthouse of Winstanley, a greater and more important structure than the old pharos.

Germinal Selection.

It can hardly be doubted that one of the “thunderclouds” threatening Darwinism, of which Weismann spoke in 1895, was this examina­tion of Weismannism by Romanes. As the case stood then some fresh strategy was needed if victory for Darwin was to be won, at least so the great leader said. It must be remembered that it was the personal selection of Darwin which was held to be in danger. Accordingly germinal selection was brought forth and remained the basis of Weismann’s later Evolution Theory of 1904 and 1909. Romanes did not live to see or assist in the disproof of this ambitious piece of work so that his “examina­tion” is so far incomplete.

The position of germinal selection is defined in Weismann’s statement that “it is the adaptive requirement itself that produces the useful direction of variation by means of selectional processes within the germ.” Here it is in a nutshell. The theory itself is consistent, and clearness has been added to the earlier evolution theory by the claim that a struggle for nutriment occurs within the fertilised ovum between the innumerable determinants of the different parts, so that maintenance or victory over weaker determinants takes place. Thus we have a survival of the fittest in petto in the germ analogous to that of the individual organisms as we see them. There is of course a resemblance here to the cellular or histonal selection of Roux, but his doctrines are not weighted with the intolerable dogma of the non-inheritance of acquired characters. But ultimately this concep­tion of germinal selection has to come down and bow to the tribunal of facts, and the remark of Weismann on Lamarckism which has been already quoted, “It seems to me that an hypothesis of this kind has performed its service and must be discarded the moment it is found to be at hopeless variance with the facts,” confronts the consistent Weismannian. And I venture to say here that germinal selection is represented by the Eddystone lighthouse of 1756–9 erected by Smeaton.

The grounds for this statement are afforded by numerous facts and experiments, to which in the later chapters I propose to add a few fresh ones, and by a growing body of opinion and authority in favour of Lamarckian factors in evolution.

Three “lighthouses” of this metaphorical sort have thus been afforded by the work of Weismann, represented by the Pharos of old, Winstanley’s Eddystone lighthouse and that of Smeaton.

Authority.

We have then Weismann and Professor Bateson definitely ranged against the position taken in this volume as to a cause or origin or variation and the inheritance of acquired characters. To these we must add the great weight of Sir E. Ray Lankester’s opinion lately given in a reply to Professor Adami that “it is very widely admitted (more correctly “claimed”) that no case of the transmission of what are called acquired characters from parent to offspring has been demonstrated in so far as those higher animals and plants which multiply by means of specialised egg-cells and sperm-cells are concerned.”

It is not necessary to mention more than these “three mighties” of the biological world.

Many others such as Prof. J. Arthur Thomson and Prof. W. K. Brooks, of Johns Hopkins University, are still unconvinced as to Lamarckian factors and ask for more evidence, and they have many to support them in their opinion and claim. There is often a tone of weariness, as well as wariness in their remarks on the matter.

In favour of the neo-Lamarckian position, with which stands or falls the suggested cause of variation, there is a growing body of opinion, with the mention of which I conclude this review.

1. The accomplished writer of Form and Function, Mr. E. S. Russell, says the theory of Lamarck “although it had little influence upon biological thought during and for a long time after the lifetime of its author, is still at the present day a living and developing doctrine.”27

2. Sir Francis Darwin from the Presidential Chair of the British Associa­tion of Science in Dublin in 1908 proclaimed his adherence to the mnemonic theory of heredity, foreshadowed by Samuel Butler and inaugurated by Semon, a condition of which is that acquired characters are inherited. This caused much stir in the camp of “our friends the enemy.”

3. Observations and experiments at variance with germinal selection and its negative presupposi­tion have been rapidly accumulated from the work of botanists and zoologists who were prepared to appeal to the tribunal of natural processes; though Weismann and some of his followers, with some reason, look upon the evidence from plants as a weak link in the chain of evidence. Many of the observations and experiments are well-known and only a mere mention of them need be made here, they are such as Mr. J. T. Cunningham’s observations on the effect of light on the under surface of flounders, Kammerer’s on the changes in the colour of salamanders to surrounding objects, and others by him on certain amphibia and reptiles especially alytes held by Professor McBride to be convincing, though the latter are to be repeated at the London Zoological Society’s gardens and are therefore sub judice—others on brine-shrimps, on the effects of change of food on bee-grubs and tadpoles, and of the change of level of environments of certain cereals—others by Henslow on plants which have never been refuted, and many by the late Prince Kropotkin. The latter have appeared at length in certain issues of the Nineteenth Century in September 1901, March 1912, October 1914, and the last in January 1919, and they deal both with plants and animals, and are too numerous to be mentioned here individually.

Again, Professor Dendy as President of the Zoological Section of the British Associa­tion of Science in September, 1914, devoted most of his address to the subject of Lamarckism and firmly claimed as a necessary factor of evolution “the direct response of the organism to environmental stimuli at all stages of development, whereby individual adapta­tion is secured, and this individual adapta­tion must arise again and again in each succeeding genera­tion.” He also maintains this position in several passages in his important work Outlines of Evolutionary Biology published in 1912.

A statement by Professor Bower, President of the Botanical section of the British Associa­tion of Science in 1914 should also be noted: “I share it (the doctrine in question) in whole or in part with many botanists, with men who have lived their lives in the atmosphere of observa­tion and experiment found in large botanical gardens and not least with a former President of the British Associa­tion, viz., Sir Francis Darwin.”

Professor Adami, in 1917, published an original work called Medical Contributions to the Study of Evolution in which from his extensive knowledge of the subject he deals with evidence of inheritance of acquired characters in lowly organisms as well as higher animals from the point of view of pathology.

Enough has been stated here to show that the dogma of Weismann or Lamarckian factors in organic evolution, quâ authority, has been in poor case during recent years, and it remains for me now to add my small quota of the authority of facts.

CHAPTER III.
THE PROBLEMS PRESENTED.

In his classical work on Heredity, Professor J. Arthur Thomson exhausts the evidence on Lamarckism available then (1908) in a manner worthy of the summing-up of an English judge. This is presented to the jury of the biological world and they are still considering it. Their verdict and his sentence are not yet delivered, and it may be they will still be long delayed. One might almost use the words of Professor Bateson, previously quoted, “on our present knowledge the matter is talked out.”

I will make one prophecy in this volume and predict that the fourth edition of this work in 1930 will contain the verdict of the jury and sentence of the distinguished judge to the effect that in the case Lamarck v. Weismann the plaintiff has won. As in the Great War the Old Contemptibles held their line with the utmost difficulty against the disciplined hosts of the greatest army ever known till then, and yet the latter found their First Battle of the Marne, so perchance it may be in the present struggle.

I introduce this chapter with an important passage from the above work on the Logical position of the Argument, in which the two possible methods of establishing the affirmative position of Lamarck are given; these are, first, actual experimental proof of transmission, and, second, a collec­tion of facts which cannot be interpreted without the hypothesis of modifica­tion inheritance. The words are:28 “The neo-Lamarckians have to show that the phenomena they adduce as illustrations of modifica­tion-inheritance cannot be interpreted as the results of selection operating on germinal variations. In order to do this to the satisfac­tion of the other side, the neo-Lamarckians must prove that the characters in question are outside the scope of natural selection, that they are non-utilitarian and not correlated with any useful characters—a manifestly difficult task. The neo-Darwinians, on the other hand, have to prove that the phenomena in question cannot be the results of modifica­tion-inheritance. And this is in most cases impossible.”29

I have placed this passage in italics because of its importance from the point of view of the two problems which I am presenting and would remark here that if only all the writers had used Professor Thomson’s term “modifications” instead of “characters” in the statement of this doctrine much confusion and evasion of plain facts would have been avoided, and yet such workers as the Mendelians, if deprived of their clear-cut term “characters” would have been less able to carry on their studies. To this point of terminology I refer below.30

In a world teeming with the life of plants and animals, and in the branch of science which seeks to interpret them, where we enter upon the unknown much sooner than in any other sphere of science, Weismann has set out to prove or maintain the most stupendous negative ever framed by the human mind. It would require generations of men to prove this negative, if it were probable, and his case rests mainly on the assumed weakness of his opponents. So what is needed and demanded from the neo-Lamarckians is the produc­tion of a few well-attested and verified facts, and, as he admits himself, then it must follow as the night the day that his followers will surrender his characteristic dogma. The more cautious leaders and teachers of the day say that this has not taken place and ask for facts, more facts and still more facts, and this attitude is both judicious and judicial, for example in a teacher so eminent as Professor J. Arthur Thomson. Scientific men, in such a position as he occupies with grace and distinc­tion, owe a serious debt of loyalty to ultimate truth and to the inquiring minds of the young students of to-day and to-morrow. Those who are in a position of inferior responsibility and honour, and more freedom, just rank and file members of the Commons’ House of Parliament, may be pardoned if they do not exhibit an excess of deference to authority and if they think for themselves.

Two Questions.

There are before the Scientific jury to-day two very vivid questions.

(1) Can modifications in the structure of an individual organism, occurring as a result of its experience, be transmitted?

(2) What is the cause of variation?

If, as Weismann taught, the answer to No. 1 is in the negative, there is little use here in trying to answer No. 2, for from the present point of view the two stand or fall together in the study of Initiative in Evolution. Such distributional answers to No. 2 as Bateson and de Vries may offer do not concern my purpose.

If No. 1 be answered in the affirmative it is sufficient for the purpose of treating initial variations from the Lamarckian standpoint, for it is hardly conceivable that Nature would neglect so simple and obvious a method of leading upwards and onwards the organisms that inhabit a changing world.

It is very clear from what is written on the subject of evolution to-day that a point d’appui in the process is earnestly desired by many workers and that Weismann’s dogma stops the way. A very significant and important remark is made by Professor W. McDougall in his small book on Physiological Psychology, with reference to the inheritance of acquired characters, that it is a “proposi­tion which most biologists at the present time are inclined to deny because they cannot conceive how such transmission can be effected. Nevertheless the rejection of this view leaves us with insuperable difficulties when we attempt to account for the evolution of the nervous system, and there are no established facts with which it is incompatible.”31 I am aware that in the scheme of observed nature there is evidence of no iron necessity, that the convenience of psychologists should be provided for, and they, like others of us, have to do the best they can with the tools and the materials which exist, and I agree with Professor Thomson in his remark on Misunderstanding No. 1, “that our first business is to find out the facts of the case, careless whether it makes our interpreta­tion of the history of life more or less difficult,”32 but I am persuaded that he will not treat lightly such a statement, from such a source, on such a subject as that I have quoted from Professor McDougall. As to his second statement on the same page “that in the supply of terminal variations, whose transmissibility is unquestioned, there is ample raw material for evolution” it is important as an opinion, and no more, and there is in the present connec­tion, an elusiveness about it which prevents one allowing it to pass. It should be noted that stress is laid upon the term “variations” and from the context this means congenital full-blown “characters” such as those that Weismann says are provided in the germ guided by selection. At any rate, initial modifications are not signified by Professor Thomson’s remark. So for evolution of forms of life it is possible the assertion may be true, but apart from distribu­tion of variations, under the process called amphimixis, some starting point is required for the initial and wholly useless stages of many variations. These may or may not become “characters” or adaptive.

What the Problems are not.

The ground may be cleared here by saying what our problems are not. There is no question as to whether Lamarckism or Darwinism represents the predominant partner in the story of life; there is no question of the “relative importance of natural selection and the Lamarckian factors in organic evolution,” though such a question may arise when once Lamarckism has received its passport from the authorities; but the time is not yet. Nor is it a question as to the reason why adaptive modifications are so constantly present in the germ. It is not a question of Nature or Nurture, but perhaps may be found to be a study of Nature and Nurture. It is not a question of Mendelian analysis, nor as to the distribu­tion of either mutations on the one hand, nor of minute fluctuating variations on the other. The problems are therefore limited in scope and ambition, and are none the worse for that, as being better open to correc­tion or support.

The Problems Considered.

It seems but natural to most persons who contemplate with any care the ever-changing and progressive drama of life in plants and animals that unquestionably the dramatis personæ by their individual response to the environments and exercise of their functions must contribute a share, however small, to their offspring. When first this view presents itself to their minds they resent as “unnatural” any other possibility. But, alas! they find that such a conclusion is not permitted in those regions where alone the white light of science shines. Here the writ of a priori does not run. The spirit of inquiry makes its challenge to every presupposi­tion and every assertion in its province—even those of current science. I have shown that this particular assump­tion of the natural man was firmly challenged by Weismann, who was not the first, but the greatest, biologist to teach that modifications are not transmitted. Accordingly, agreeable and convenient as it would be to assume the Lamarckian hypothesis as a working one, it needs in the present day to be supported by evidence before this can be allowed. Facts, then, against Weismann’s dogma are demanded and of such a kind as will satisfy so powerful an advocate of his own views. In passing it may be remarked again that there is nothing so misleading as facts, except statistics, and for both sides to bear in mind the warning of a French writer that in such inquiries as this we should be careful lest we find the facts for which we are looking.

To meet the conditions laid down in Professor Thomson’s Canon I propose to describe certain phenomena which are adduced as instances of modifications in certain mammals whose structure and mode of life are intimately known, and whose ancestry is little in dispute.33 The most convincing of these lines of evidence are those which are shown to be outside the range of any form of selection, as well as the distributional factors of Mendel and de Vries. It is well to enumerate here the six different factors in organic evolution which might claim a share in the produc­tion of such humble phenomena as form the subject-matter of this volume—they are:

1. Personal Selection of Darwin.
2. Sexual Selection.
3. Histonal or Cellular Selection of Roux.
4. Germinal Selection.
5. Inheritance according to Mendelian principles.
6. Inheritance of Mutations.

There is a somewhat severe and ill-defined condition attached to the formula in question for it demands that such modifications as will satisfy the neo-Darwinians shall not be correlated with any useful character.34 If such a conditio sine quâ non were taken too literally it would at once foreclose the case as to the possibility of transmission of modifications at all, the questions of issue ought in that case never to have been raised—and, cadit quæstio. This cannot be the intention of the biologist who propounds the formula. It could not reasonably be carried so far as to insist that a modifica­tion arising from a certain habit, active or passive, in an animal, and which on that account, and on paper, may loosely be said to be ‘correlated’ with it, is to be ruled out. That would be tantamount to saying for example, that, because an animal must lie down in a certain attitude when it rests, or walk or run in a certain manner, in other words that it is useful to exist, certain modifications claimed to be due to these fundamental parts of existence must be excluded from the inquiry. The neo-Darwinian is not a critic easy to be entreated, but that he would not claim. Let me take one example of what I mean. A short-haired dog will spend a considerable part of its daily life, and presumably a long line of ancestors did so too, lying with its forelegs planted in front of its chest and its head either raised in the air when awake or resting on the upper surface of the forelegs (of course the familiar attitude of a dog with its body and head curled up and fore-legs doubled is not referred to here). If the hairy coat be examined over its neck and jaw, which lie in this attitude, on and against the forelegs, a remarkable reversal of the direction of the hairs is found and the outline of this forms an accurate mould of the surface applied to the forelegs. This is transmitted of course from previous generations of domestic dogs. A precisely analogous reversal of the hairs is found on the under or extensor surfaces of the forelegs, matching with wonderful exactness the area of pressure of these on the ground, and anyone can see it who has a canine friend of the fox-terrier type. Long-haired dogs display it less neatly outlined. An instance such as this cannot be excluded from the evidence forthcoming because it is correlated with the useful “character” of lying in a certain attitude. Such a phenomenon, many similar to which will be seen later, had at any rate an origin de novo at some time in the ancestral stock, and in some way. To discover these is part of my business. The boldest neo-Darwinian will not claim that this arrangement of a dog’s hair arose by selectional processes within the germ either in the initial or completed stages.

Correlation.

The term “correla­tion” is somewhat scornfully said by Weismann to be “unquestionably a fine word,” and it has indeed in biological writings a very varied set of meanings. I will not vex the reader with a reference to our old friend Mesopotamia, but mention what Dr. Vernon in Variation in Animals and Plants says of the term, referring to the relation between stature and head-index in man: “Such a statement must vary according to the notion of the observer as to what does and what does not constitute correla­tion.”35 The most approved and precise meaning of the loose term in question is that associated with the work of the biometricians, and a few examples from Dr. Vernon’s book will show how far this concep­tion of correla­tion is removed from the literal applica­tion of Professor Thomson’s formula. Dr. Vernon treats of such phenomena as the correla­tion of the long heads of greyhounds with length of legs, contrasting them with the shortened heads and legs of bull-dogs. He describes also the correla­tion in man between the stature and length of forearm from elbow to tip of middle finger, correlated measurements of crabs, of external structures of prawns, the tufts of Polish fowls correlated with perforations in the skull, also certain constitutional peculiarities with colour of skin. These few cases are enough to give an idea of the more precise and fairer accepta­tion of the term, but while these form a useful subject for minute study it may be remarked that they agree also with Lamarckian factors as to their origin and development. They are much more in line with Darwin’s use of the word and are strangely reminiscent of the well-known example of the Irish elk with its great head and horns which was brought forward in favour of Lamarckism by Herbert Spencer. They breathe an atmosphere of physiology rather than anatomy, or function than form.

Enough has been said here by way of defining the terms of the issue. The negative we have to sustain is that the following facts and observations declare that certain small modifications cannot be governed by selection and are not correlated with useful characters. It will be shown later that Professor Thomson’s stringent condition is not in all of them compiled with, but that, in spite of this, the probability of their being valid examples of Lamarckism in practice is immense.

CHAPTER IV.
INITIAL VARIATIONS AND TOTAL EXPERIENCE.

The present chapter is on a priori lines and will perhaps be dismissed with a wave of the hand or hurriedly skimmed over, but I pray the reader at least to read the two or three last pages of it. It is at any rate suggestive, and perhaps I may anticipate the comments of the neo-Darwinian and throw myself on his mercy by mentioning a remark of the late Sir Andrew Clark, prince of physicians and genial cynic, which he made to a patient in my presence. A lady not distinguished for depth of thought asked him a rather silly question in medicine. As if offended he drew himself up, holding in his hand a cup of tea which he was enjoying, and replied at once “Madam, you must get a younger and more inexperienced man than I am to answer you that question.”

A very high degree of probability may be attached to the presupposi­tion that Lamarckian factors, even in their humblest form, may enter into the story of the organisms as historical and living beings. Every hypothesis in matters of science, or, to put it at its lowest, every scientific guess must transcend the evidence at the time available.

Total Experience.

The sugges­tion I venture to make here is that if we take a comprehensive view of certain two great groups of phenomena in nature, which may be termed universal in their extent, it is difficult to conceive that they are not causally connected in the sense that one is the universal antecedent of the other. On the one hand are found universal minute differences, not only between any pair of organisms, but of any two corresponding parts of any organism, even to the size and shape of each leaf on each plant. On the other is universal discontinuity of total experience of all organisms. This term includes all the stimuli of use and environment to which an organism is exposed throughout its whole existence, and its response to them. It includes the whole succession of active and passive stimuli which begin with the formation of a zygote in higher forms, for example, and continue till the death or end of reproductive life of the individual. It stands for such stimuli as arise from habitat on or in the earth, in various levels of salt or fresh water, in sea, lake, pool and river, and in the branches of trees, from climate, from degrees of light, temperature, moisture and wind, from presence and activity of enemies and rivals, from supplies of food, from geographical and topographical position. Such an enumera­tion of stimuli might be much extended if it would serve any purpose. But it is enough to say that the number of such stimuli, and the varying degrees in which these are received and responded to, have hardly any limit which we can conceive. It is a very different and harder task to find out the propor­tion in which such stimuli are advantageous, injurious or indifferent to the organisms, but it may be taken as certain that the vast majority are indifferent in the sense of producing structural change, and, that the advantageous stimuli transmit structural effects to offspring, is only a matter of very strong probability. If the above two groups of phenomena are not causally connected they are intertwined with remarkable closeness and perversity. This aspect of the “web of life” has received attention, and deserves more.

Discontinuous Environments.

Some reference must be made here to observations of Prof. Bateson in his work on variation. In the first place he makes a most valuable statement that “the environment as the directing cause is essential to Lamarck’s theory and as the limiting cause is essential to the doctrine of Natural Selection”36 (which I venture to place in italics on account of its importance to all who seek the pathway of organic evolution) and points out also that “diversity of environment is thus the measure of diversity of specific form. Here then we meet the difficulty that diverse environments often shade into each other insensibly and form a continuous series.”37 This is clearly true and important to the subjects he is discussing. But in regard to the concep­tion with which I am here concerned, that of total experience of organisms, it must be remembered that there is no such thing as an environment apart from the living beings that it environs, and that from this point of view there is no such thing in the world of nature as a continuous environment. The environment of two amœbæ living under a cover-glass is, for them, far from continuous. In their infinitesimal existence the exact position they occupy in the environing drop of fluid, in which the propor­tion of their humble fare at one side of the cover-glass is not the same as that on the opposite side, renders their environments discontinuous, or different from that of another amœba occupying a position and “environment” which we should consider identical. And this considera­tion applies to the other few “tropisms” which enter into their little lives. This statement may be difficult to prove, but it is a necessity of thought. An illustra­tion may assist one in visualizing such discontinuity. A fly is seen crawling at its own pace up one of the great pillars of St. Paul’s Cathedral. It comes to one of the thin layers of cement worn down with age and so delicate that a man can just see it in a good light. The fly pauses, and passes into what is for it a chasm, with as much relative delibera­tion as the man would show in passing across a deep railway cutting. The number of pictures that could be made of cases corresponding to that of the amœba is incalculable. A few will suffice. Two plants of the common nettle are growing on the south side of a ditch in a lane, one rooted a foot higher than the other. The upper one receives throughout its life from wind and sun stimuli slightly different from those received by the lower, and from the soil slightly less moisture. These again receive stimuli very different from another pair on the northern side of the lane. Again in windy weather a clump of sycamores facing the south-west in England, and situated on the ridge of an eminence, will receive very different stimuli from a similar clump on the north-eastern slope of this eminence, and will demonstrate the fact, as to force of wind, by a marked slope to the North East. Even in either of the clumps the individual trees present varying degrees of slope according to their position. The total experience of these two clumps of sycamores and of any two in each clump is obviously different. In a windy situation you can tell in July which is the prevailing wind by noting the main inclina­tion of the ears of corn in a field. Again two male sticklebacks in a pond will make nests for the eggs, there to be deposited, and one will choose a spot on the southern and another on the northern side of a little promontory of soil and stones at the edge of the pond. One will find ready for him materials for building his nest different from those of his rival, and he and his wife and family will receive for that season very different stimuli, and so will the stimuli differ in other phases of their existence in a pond occupying a few square yards. On a sandy bank in a garden facing south you may discover two little caves ingeniously hidden by a small opening, and in each of them you can see a toad. Though these are only a few feet apart one is more widely open to sun and wind than the other and one deeper than the other, and whatever the other activities of the two toads may be in their little shelters, they receive stimuli different in strength and number. On another bank in the same garden less exposed to view, and altogether more sheltered from sun and wind and enemies, a robin has built a well-hidden nest. If the six fledglings in the nest are watched when the mother is absent they are seen to occupy very different positions of comfort, pressure and warmth. When the mother-bird returns from marketing she is hardly impartial in the amount of food she puts into their open beaks. But the slight and perhaps unimportant inequality of their experiences as fledglings is nothing to that which follows when they fly abroad, and which continues to the end of their lives, the life of a robin being somewhere about ten years long. The differences of the total experience of the six young robins is easy to picture. Again, surely, the total experience of two fleas on the body of one plague-rat must be for such small creatures of importance to their welfare, according as their respective “pitches” are on the abdomen, back or legs of the host. When the life-history of a human being is told in full the discontinuity of his total experience needs no proof. The proof is written large before our eyes. But, perhaps, one example may be given. There are two very eminent living writers, whose light has certainly for some years not been hidden under a bushel, Mr. Chesterton and Mr. George Bernard Shaw. We may be said to know them well. Leaving out of sight the Celtic strain claimed by one, and indeed all inherited differences, we see two men of perhaps equal ability, near of an age, both living in London, both living by their pen, both in easy circumstances. When one considers for a moment the different company these two men keep, their different and opposing outlook on life, their different and opposing forms of diet for their minds and bodies (I know which of the two diets of those men I would choose and with which of them I would prefer to be cast on a desert island) one can only say that the total experience of Mr. Chesterton differs from that of Mr. Shaw as cheese from chalk, which things, incidentally, are an allegory in the philosophy of life.

The thought here briefly expressed falls well into line with Prof. Bateson’s statement that the directing cause of the environment is essential to the theory of Lamarck, and I do not hesitate to add to it the assertion that all environment, in the wide sense of total experience, is discontinuous. There are no such phenomena in total experience as unit-characters of allied forms, small variations are the rule. Without doubt a large propor­tion of the stimuli received by an organism are as figures written on a slate and at once wiped off. They are as the snows of yester year. The most they do is to contribute in their measure to the metabolism of the organism, being too numerous and minute to affect any structural change. In a higher form of life none but those which are frequently repeated in the individual and in succeeding generations can effect any structural response.

Mould and Sieve.

It will be remembered that a single example was given of a short-haired dog in which its common habit of lying was associated with a certain pattern of hair. This introduces and illustrates the very wide concep­tion of a moulding process undergone by an organism. It is one familiar to biologists and very much so to Professor Thomson in his various writings. Not less is he an exponent of the metaphorical work of the sieve of natural selection. I therefore claim nothing new when, with the temerity of certain persons treading where others are said to fear to do so, I invent an inclusive term and propose to call the two fundamental factors of organic evolution Plasto-diēthēsis38 in which the conceptions of mould and sieve are included and hyphenated. This word is no more proposed for its elegance than are panmixia, amphimixis and tetraplasty, though perhaps it may be the etymological superior of one or more of these. It is at any rate inclusive and perhaps sufficiently audacious to assure the inventor of the title of Dr. Pangloss of controversial memory. But as hard words break no bones I have taken this risk and it would appear to be a convenient “conceptual counter” and even Professor Karl Pearson could not consistently forbid it. It has at any rate the merit of having a meaning clear to all friends and opponents alike of Lamarckism. It will be observed that the two words are placed in what I take to be their natural order as expressive of the Alpha and Omega of the story of organic evolution. The moulding process is claimed to precede that of the sieve, as physiology precedes anatomy and function structure, in that form of biological specula­tion which is held here to be the soundest.39

So the banns between Lamarck and Darwin are published, not for the first time of asking, and who shall say that there is cause or just impediment why these two should not be joined together in holy matrimony?

I conclude this chapter with a passage from the life of Columbus by Washington Irving which affords a fitting parallel from history in the higher development and union of two formerly hostile Kingdoms, and the moral of it is clear and simple. But as a forensic junior I beg to enter a caveat to the effect that though the name of Columbus occurs no sugges­tion is made of the discovery of a New World.

“It has been well observed of Ferdinand and Isabella that they lived together not like man and wife whose estates are in common, under the orders of the husband, but like two monarchs strictly allied. They had separate claims to sovereignty in virtue of their separate Kingdoms, and held separate councils. Yet they were so happily united by common views, common interests, and a great deference for each other, that this double administra­tion never prevented a unity of purpose and action. All acts of sovereignty were executed in both their names; all public writings subscribed with both their signatures; their likenesses were stamped together on the public coin, and the royal seal displayed the united arms of Castile and Aragon.”

CHAPTER V.
METHOD OF PROOF.

In a matter of scientific inquiry one cannot go far wrong if one follows the advice of Henri Poincaré, who lays down certain principles of method; four of these are the following:—

(1) The most interesting facts are those which can be used several times, those which have a chance of recurring.

(2) The facts which have a chance of recurring are simple facts.

(3) Method is the selection of facts, and accordingly our first care must be to devise a method.

(4) We should look for the cases in which the rule established stands the best chance of being found fault with.

The groups of facts described in the succeeding chapters are in agreement with these principles in the main, and are perhaps like a dust heap for their intrinsic value. But one knows that before now among a good deal of débris a rusty key has been found which has opened a cabinet containing certain treasures, and in the hands of someone else than the finder has produced useful results.

The headings of the chapters describe the facts, and there is no need to enumerate them here. The first and largest group is studied according to a method which is in a measure applied to all the others. Most of them are external or superficial phenomena and accordingly are open to others beside the expert for observa­tion and corrobora­tion, or the reverse. The typical plan adopted is as follows: a large number of related phenomena are chosen, and the more prominent of these are observed and described. Keeping in mind the two plain issues laid down, the origin of initial modifications and their transmission, I have selected the facts because, especially such as those of the hair, they are very simple, of wide distribu­tion in animals well known to us, such as the domestic horse and man, and none are brought forward which any other observer cannot study for himself if he has some anatomical and physiological knowledge, some training and care in recording observations. In most centres of popula­tion there are still left a good supply of horses in streets and stables, of preserved specimens in museums and living ones in zoological gardens, and of hairy young men who will hardly refuse a polite request to examine the minute hairs clothing their trunks and limbs. One has to pursue a certain amount of that study which may be called the sister of plant-ecology, that is, animal-ecology or the behaviour of animals at home. The student of these matters, it may be freely admitted, will complain, unless he has some hypothesis or line of thought to follow, that he has been set down in a valley in which the bones are very many and very dry. But, armed or primed with an hypothesis, he may find an affirmative answer to his question “Can these bones live?” Every group of natural phenomena, without exception, has some meaning for those who will interpret nature rather than bully and slight her, and whatever anointed king may claim sovereignty over it the humble fact cannot be denied that “whatever phenomenon is, is.”40 Again I would refer to Howes’ inspiring note: “We live by ideas; we advance by a knowledge of the facts; content to discover the meaning of phenomena, since the nature of things will be for ever beyond our grasp.”41 The facts adduced are simple, have a chance of recurring and are widely distributed among multicellular animals—the botanists and plants can very well take care of themselves. I must once more state that I am attaching to the considered facts a value of a somewhat unusual kind—their intrinsic unimportance. For anyone who has had to encounter the skilful dialectics and counter-attacks of a well-equipped neo-Darwinian it is well that he should remember the maxim of Napoleon, “Be vulnerable nowhere.” It is necessary to show evidence for Lamarckian factors in which no degree of selective value, survival-value, can be seen by hostile sharp-shooter while he works in his trench. The main line of defence, or more correctly what Hindenburg would call “offensive-defence,” is therefore made to rest on the phenomena of hair-direction, which, I submit, are impregnable to the forces of selection, probably in all the hairy mammals, but certainly in that hairy animal called Man.

Thesis.

If these groups of phenomena were being studied apart from the hypothesis they support, a much more full treatment of all of them would be required, such as I have given to those of hair-direction in a book published in 1903 on Direction of Hair in Animals and Man. The limited thesis, however, here upheld is that the phenomena are produced by the factors of stimuli and response in the course of the total experience of the organism, that the essence of the matter is the produc­tion of initial modifications, that instances of these in well-known animals are produced before our eyes by ascertainable mechanical stimuli, and that, especially in those of hair-direction, experiment is adduced in proof of the thesis that some modifications are transmitted.

Procedure.

The order of proceedings may be tabulated thus:—

(1) Observation of selected facts.

(2) Evidence that certain of these are produced in the lifetime of the individual.

(3) Evidence that among the facts of direction of hair and others there is to be seen an orderly evolution rather than a casual appearance of the changes noted.

(4) An hypothesis as to their production.

(5) Exclusion of selection as a possible cause of these, and of correla­tion as properly understood.

(6) Experiment in verification of the Lamarckian interpreta­tion of the phenomena.

And here, before I hear some Prince Henry of the genus Weismann, Mendel or Gallio groan aloud: “This intolerable amount of sack,” I proceed to offer him a few loaves of home-made bread.

CHAPTER VI.
EVIDENCE FROM ARRANGEMENT OF HAIR.

Ex Uno Disce Omnes.

The singular arrangement of hair on the forearm of man is the subject of some curious statements by Darwin, Wallace and Romanes, and these suggested to me twenty years ago the following line of thought. To many minds the text will appear a humble one, but it opens many avenues of inquiry.

These three illustrious men are all more or less inaccurate and incomplete in their descriptions of the hair on man’s forearm, though Romanes42 gives a drawing which supplements his written account. They looked upon it as a vestige of the pattern of hair on the forearm of existing anthropoid apes, especially the orang, in whom its fully-developed form was an adapta­tion governed by Natural Selection. Of the three, Wallace is the most uncompromising on behalf of this view, Romanes rather accepts it en passant, and Darwin in a long passage43 adopts it with some reserve and his usual respect for the work of his great co-worker, as the most probable explana­tion of a fact which lay heavy on his scientific conscience. Indeed, for all these great men it was a crux, though Romanes, with his Lamarckian views, need not have found much difficulty with an alternative account of it.44

At the time when these statements were made, the lineal ancestors of man were much more definite personages than they are now, as Arthur, the legendary Celtic hero, was formerly held to be an historical personage more than is the case now. These ancestors were generally believed then to be found among the four existing anthropoid apes. The picture of our ancestor among the apes, as given by Wallace, in connec­tion with this state of the hair on his forearm, represents him as spending much of his time like the gorilla, who, according to Livingstone, “sits in pelting rain with his hands over his head.” He would no doubt find the thatch-like arrangement of the hair a tolerably efficient umbrella, but one may doubt very much if so clever a denizen of the tropics would fail to find under the great branches of trees, in a tropical forest, a better covering and one more like the roofs of our houses. But when we cannot find a roof to our heads we—and the orang or gorilla—naturally employ a substitute, and not otherwise. Be that as it may, it is doubtful if the thatch of his forearms would supply him with that survival value on which the theory of Selection depends, to say nothing of the fact that in its incipient stage the reversal of the slope of hair, inherited from the lemur stock, would be trivial and useless.

But one must ask: “Did man’s Simian ancestor really loaf away so much of his time in this dull manner? and was the running-off of rain so frequent and imperative a need as to make him set to work to invent this special adapta­tion?”

After some millions of years have passed since his day we are not in a position to go beyond speculations, and this one seems barely credible, moreover, it is quite unnecessary, as certain following facts will show.

Steps of the Inquiry.

Having expounded the text and its context, I would mention that in 1897 I came across these views of biologists as to the very strange arrangement of hair on man’s forearm, and was struck with the inadequacy of the theory of Darwin, Wallace and Romanes to account for the state of things which every man can find, if he looks for it, on his own forearm. I examined a large number of apes and monkeys so as to test the theory, and the results were published in Nature, Vol. 55, under the title “Certain vestigial characters in Man.” Suffice it to say that from the evidence I brought forward one had to choose between two heresies: either to deny the Simian ancestry of man or to affirm the inheritance of some acquired characters; and I chose the latter. The choice of “evils” or heresies which had to be made then will serve as an introduc­tion to all that follows.

This article was followed by a paper at the Zoological Society of London on “The Hair-Slope in certain Typical Mammals,” and after this came a paper at the same Society, giving evidence and reason why certain patterns of hair in some mammals should rank as specific characters. Various other papers at the Anatomical Society of Great Britain and Ireland were read and published and others at the Zoological Society, in which different regions of the hairy coat of man and lower mammals were dealt with. In 1903 the whole subject of the Direction of Hair in Animals and Man was treated in a book freely illustrated.

I then followed the advice of Horace and left the subject alone for nine years, during which time my further observations and reflections served but to confirm, except in two or three unimportant details, the results and conclusions in the book and papers of an earlier date. The connec­tion between the habits of an animal and the distribu­tion of its hairy coat were always cropping up, and I saw then and see now no possible explana­tion of the connec­tion than that the former is the efficient cause of the latter.

How the Hair is Arranged on the Forearm.

Returning now to the text, the remarkable arrangement of hair on man’s forearm, attention may be directed to the accompanying figure of the forearm of a lemur, an ape and man, in which the extensor or back view of this limb-segment is shown, the heavy “war-arrows” being employed to direct the attention of the reader to the main lines in which the hair-streams flow. The front or flexor surfaces in the lemur and ape are not shown because they are precisely like the corresponding back surfaces, and the flexor surface in man is shown in the figure. The figures are so much like diagrams that a very little detailed descrip­tion will suffice. For the examina­tion of the hair on man’s forearm the best subject is a dark-haired youth, and it is easily traced, though in any hairy subject it can be shown up well by placing the forearm in water for a minute and allowing the water to drain off. The normal and congenital hair-slope on the forearm is then well displayed.

On the front surface of man’s forearm the hairs point away from the elbow and divide in the middle of the surface into two streams, one passing to the outer and the other to the inner border in a downward gentle curve, and they join the streams of hair on the back surface. In this pattern there is nothing very peculiar, for it is shared by many monkeys.

When the back surface is examined it is found to present an arrangement of the hair which is unique among hairy mammals. The figure shows the eccentric course taken by the hair on the back surface. In the centre, exactly along the extensor border of the ulna, from the wrist to the point of the elbow, the hair-stream has been bold enough to turn straight upwards in a narrow line, and it was here that our three great leaders saw their chance of claiming for Selection a tiny bit of territory, a kind of Duchy of Luxembourg between two great States, though, as I proceed to show, the claim is disallowed and untenable.