While I do not concur in sundry of the statements and conclusions contained in the article entitled "A Great Confession," contributed by the Duke of Argyll to the last number of this Review, yet I am obliged to him for having raised afresh the question discussed in it. Though the injunction "Rest and be thankful," is one for which in many spheres much may be said—especially in the political, where undue restlessness is proving very mischievous; yet rest and be thankful is an injunction out of place in science. Unhappily, while politicians have not duly regarded it, it appears to have been taken to heart too much by naturalists; in so far, at least, as concerns the question of the origin of species.

The new biological orthodoxy behaves just as the old biological orthodoxy did. In the days before Darwin, those who occupied themselves with the phenomena of life, passed by with unobservant eyes the multitudinous facts which point to an evolutionary origin for plants and animals; and they turned deaf ears to those who insisted on the significance of these facts. Now that they have come to believe in this evolutionary origin, and have at the same time accepted the hypothesis that natural selection has been the sole cause of the evolution, they are similarly unobservant of the multitudinous facts which cannot rationally be ascribed to that cause; and turn deaf ears to those who would draw their attention to them. The attitude is the same; it is only the creed which has changed.

But, as above implied, though the protest of the Duke of Argyll against this attitude is quite justifiable, it seems to me that many of his statements cannot be sustained. Some of these concern me personally, and others are of impersonal concern. I propose to deal with them in the order in which they occur.

On page 144 the Duke of Argyll quotes me as omitting "for the present any consideration of a factor which may be distinguished as primordial;" and he represents me as implying by this "that Darwin's ultimate conception of some primordial 'breathing of the breath of life' is a conception which can be omitted only 'for the present.'" Even had there been no other obvious interpretation, it would have been a somewhat rash assumption that this was my meaning when referring to an omitted factor; and it is surprising that this assumption should have been made after reading the second of the two articles criticised, in which this factor omitted from the first is dealt with: this omitted third factor being the direct physico-chemical action of the medium on the organism. Such a thought as that which the Duke of Argyll ascribes to me, is so incongruous with the beliefs I have in many places expressed that the ascription of it never occurred to me as possible.

Lower down on the same page are some other sentences having personal implications, which I must dispose of before going into the general question. The Duke says "it is more than doubtful whether any value attaches to the new factor with which he [I] desires to supplement it [natural selection]"; and he thinks it "unaccountable" that I "should make so great a fuss about so small a matter as the effect of use and disuse of particular organs as a separate and a newly-recognised factor in the development of varieties." I do not suppose that the Duke of Argyll intended to cast upon me the disagreeable imputation, that I claim as new that which all who are even slightly acquainted with the facts know to be anything rather than new. But his words certainly do this. How he should have thus written in spite of the extensive knowledge of the matter which he evidently has, and how he should have thus written in presence of the evidence contained in the articles he criticizes, I cannot understand. Naturalists, and multitudes besides naturalists, know that the hypothesis which I am represented as putting forward as new, is much older than the hypothesis of natural selection—goes back at least as far as Dr. Erasmus Darwin. My purpose was to bring into the foreground again a factor which has, I think, been of late years improperly ignored; to show that Mr. Darwin recognized this factor in an increasing degree as he grew older (by showing which I should have thought I sufficiently excluded the supposition that I brought it forward as new); to give further evidence that this factor is in operation; to show there are numerous phenomena which cannot be interpreted without it; and to argue that if proved operative in any case, it may be inferred that it is operative on all structures having active functions.

Strangely enough, this passage, in which I am represented as implying novelty in a doctrine which I have merely sought to emphasize and extend, is immediately succeeded by a passage in which the Duke of Argyll himself represents the doctrine as being familiar and well established:—

In none of the assertions contained in this passage can I agree. Had the inheritance of "functional and structural decline" been "not generally disputed," half my argument would have been needless; and had the inheritance of "increased strength and development" caused by use been recognized, as "illustrated by many examples," the other half of my argument would have been needless. But both are disputed; and, if not positively denied, are held to be unproved. Greyhounds and pointers do not yield valid evidence, because their peculiarities are more due to artificial selection than to any other cause. It may, indeed, be doubted whether greyhounds use their legs more than other dogs. Dogs of all kinds are daily in the habit of running about and chasing one another at the top of their speed—other dogs more frequently than greyhounds, which are not much given to play. The occasions on which greyhounds exercise their legs in chasing hares, occupy but inconsiderable spaces in their lives, and can play but small parts in developing their legs. And then, how about their long heads and sharp noses? Are these developed by running? The structure of the greyhound is explicable as a result mainly of selection of variations occasionally arising from unknown causes; but it is inexplicable otherwise. Still more obviously invalid is the evidence said to be furnished by pointers and setters. How can these be said to exercise their organs of smell more than other dogs? Do not all dogs occupy themselves in sniffing about here and there all day long: tracing animals of their own kind and of other kinds? Instead of admitting that the olfactory sense is more exercised in pointers and setters than in other dogs, it might, contrariwise, be contended that it is exercised less; seeing that during the greater parts of their lives they are shut up in kennels where the varieties of odours, on which to practise their noses, is but small. Clearly if breeders of sporting dogs have from early days habitually bred from those puppies of each litter which had the keenest noses (and it is undeniable that the puppies of each litter are made different from one another, as are the children in each human family, by unknown combinations of causes), then the existence of such remarkable powers in pointers and setters may be accounted for; while it is otherwise unaccountable. These instances, and many others such, I should have gladly used in support of my argument, had they been available; but unfortunately they are not.

On the next page of the Duke of Argyll's article (page 145), occurs a passage which I must quote at length before I can deal effectually with its various statements. It runs as follows:—

Had there not been the Duke of Argyll's signature to the article, I could scarcely have believed that this passage was written by him. Remembering that on reading his article in the preceding number of this Review, I was struck by the extent of knowledge, clearness of discrimination, and power of exposition, displayed in it, I can scarcely understand how there has come from the same pen a passage in which none of these traits are exhibited. Even one wholly unacquainted with the subject may see in the last two sentences of the above extract, how strangely its propositions are strung together. While in the first of them I am represented as bringing forward a "new factor," I am in the second represented as saying that I mentioned it twenty years ago! In the same breath I am described as claiming it as new and asserting it as old! So, again, the uninstructed reader, on comparing the first words of the extract with the last, will be surprised on seeing in a scientific article statements so manifestly wanting in precision. If "natural selection is a mere phrase," how can Mr. Darwin, who thought it explained the origin of species, be regarded as wise? Surely it must be more than a mere phrase if it is the key to so many otherwise inexplicable facts. These examples of incongruous thoughts I give to prepare the way; and will now go on to examine the chief propositions which the quoted passage contains.

The Duke of Argyll says that "heredity is the central idea of natural selection." Now it would, I think, be concluded that those who possess the central idea of a thing have some consciousness of the thing. Yet men have possessed the idea of heredity for any number of generations and have been quite unconscious of natural selection. Clearly the statement is misleading. It might just as truly be said that the occurrence of structural variations in organisms is the central idea of natural selection. And it might just as truly be said that the action of external agencies in killing some individuals and fostering others is the central idea of natural selection. No such assertions are correct. The process has three factors—heredity, variation, and external action—any one of which being absent, the process ceases. The conception contains three corresponding ideas, and if any one be struck out, the conception cannot be framed. No one of them is the central idea, but they are co-essential ideas.

From the erroneous belief that "heredity is the central idea of natural selection" the Duke of Argyll draws the conclusion, consequently erroneous, that "natural selection includes and covers all the causes which can possibly operate through inheritance." Had he considered the cases which, in the Principles of Biology, I have cited to illustrate the inheritance of functionally-produced modifications, he would have seen that his inference is far from correct. I have instanced the decrease of the jaw among civilized men as a change of structure which cannot have been produced by the inheritance of spontaneous, or fortuitous, variations. That changes of structure arising from such variations may be maintained and increased in successive generations, it is needful that the individuals in whom they occur shall derive from them advantages in the struggle for existence—advantages, too, sufficiently great to aid their survival and multiplication in considerable degrees. But a decrease of jaw reducing its weight by even an ounce (which would be a large variation), cannot, by either smaller weight carried or smaller nutrition required, have appreciably advantaged any person in the battle of life. Even supposing such diminution of jaw to be beneficial (and in the resulting decay of teeth it entails great evils), the benefit can hardly have been such as to increase the relative multiplication of families in which it occurred generation after generation. Unless it has done this, however, decreased size of the jaw cannot have been produced by the natural selection of favourable variations. How can it then have been produced? Only by decreased function—by the habitual use of soft food, joined, probably, with disuse of the teeth as tools. And now mark that this cause operates on all members of a society which falls into civilized habits. Generation after generation this decreased function changes its component families simultaneously. Natural selection does not cover the case at all—has nothing to do with it. And the like happens in multitudinous other cases. Every species spreading into a new habitat, coming in contact with new food, exposed to a different temperature, to a drier or moister air, to a more irregular surface, to a new soil, &c., &c., has its members one and all subject to various changed actions, which influence its muscular, vascular, respiratory, digestive, and other systems of organs. If there is inheritance of functionally-produced modifications, then all its members will transmit the structural alterations wrought in them, and the species will change as a whole without the supplanting of some stocks by others. Doubtless in respect of certain changes natural selection will co-operate. If the species, being a predacious one, is brought, by migration, into the presence of prey of greater speed than before; then, while all its members will have their limbs strengthened by extra action, those in whom this muscular adaptation is greatest will have their multiplication furthered; and inheritance of the functionally-increased structures will be aided, in successive generations, by survival of the fittest. But it cannot be so with the multitudinous minor changes entailed by the modified life. The majority of these must be of such relative unimportance that one of them cannot give to the individual in which it becomes most marked, advantages which predominate over kindred advantages gained by other individuals from other changes more favourably wrought in them. In respect to these, the inherited effects of use and disuse must accumulate independently of natural selection.

To make clear the relations of these two factors to one another and to heredity, let us take a case in which the operations of all three may be severally identified and distinguished.

Here is one of those persons, occasionally met with, who has an additional finger on each hand, and who, we will suppose, is a blacksmith. He is neither aided nor much hindered by these additional fingers; but, by constant use, he has greatly developed the muscles of his right arm. To avoid a perturbing factor, we will assume that his wife, too, exercises her arms in an unusual degree: keeps a mangle, and has all the custom of the neighbourhood. Such being the circumstances, let us ask what are the established facts, and what are the beliefs and disbeliefs of biologists.

The first fact is that this six-fingered blacksmith will be likely to transmit his peculiarity to some of his children; and some of these, again, to theirs. It is proved that, even in the absence of a like peculiarity in the other parent, this strange variation of structure (which we must ascribe to some fortuitous combination of causes) is often inherited for more than one generation. Now the causes which produce this persistent six-fingeredness are unquestionably causes which "operate through inheritance." The Duke of Argyll says that "natural selection includes and covers all the causes which can possibly operate through inheritance." How does it cover the causes which operate here? Natural selection never comes into play at all. There is no fostering of this peculiarity, since it does not help in the struggle for existence; and there is no reason to suppose it is such a hindrance in the struggle that those who have it disappear in consequence. It simply gets cancelled in the course of generations by the adverse influences of other stocks.

While biologists admit, or rather assert, that the peculiarity in the blacksmith's arm which was born with him is transmissible, they deny, or rather do not admit, that the other peculiarities of his arm, induced by daily labour—its large muscles and strengthened bones—are transmissible. They say that there is no proof. The Duke of Argyll thinks that the inheritance of organs enfeebled by disuse is "not generally disputed;" and he thinks there is clear proof that the converse change—increase of size consequent on use—is also inherited. But biologists dispute both of these alleged kinds of inheritance. If proof is wanted, it will be found in the proceedings at the last meeting of the British Association, in a paper entitled "Are Acquired Characters Hereditary?" by Professor Ray Lankester, and in the discussion raised by that paper. Had this form of inheritance been, as the Duke of Argyll says, "not generally disputed," I should not have written the first of the two articles he criticizes.

But supposing it proved, as it may hereafter be, that such a functionally-produced change of structure as the blacksmith's arm shows us, is transmissible, the persistent inheritance is again of a kind with which natural selection has nothing to do. If the greatly strengthened arm enabled the blacksmith and his descendants, having like strengthened arms, to carry on the battle of life in a much more successful way than it was carried on by other men, survival of the fittest would ensure the maintenance and increase of this trait in successive generations. But the skill of the carpenter enables him to earn quite as much as his stronger neighbour. By the various arts he has been taught, the plumber gets as large a weekly wage. The small shopkeeper by his foresight in buying and prudence in selling, the village-schoolmaster by his knowledge, the farm-bailiff by his diligence and care, succeed in the struggle for existence equally well. The advantage of a strong arm does not predominate over the advantages which other men gain by their innate or acquired powers of other kinds; and therefore natural selection cannot operate so as to increase the trait. Before it can be increased, it is neutralized by the unions of those who have it with those who have other traits. To whatever extent, therefore, inheritance of this functionally-produced modification operates, it operates independently of natural selection.

One other point has to be noted—the relative importance of this factor. If additional developments of muscles and bones may be transmitted—if, as Mr. Darwin held, there are various other structural modifications caused by use and disuse which imply inheritance of this kind—if acquired characters are hereditary, as the Duke of Argyll believes; then the area over which this factor of organic evolution operates is enormous. Not every muscle only, but every nerve and nerve-centre, every blood-vessel, every viscus, and nearly every bone, may be increased or decreased by its influence. Excepting parts which have passive functions, such as dermal appendages and the bones which form the skull, the implication is that nearly every organ in the body may be modified in successive generations by the augmented or diminished activity required of it; and, save in the few cases where the change caused is one which conduces to survival in a pre-eminent degree, it will be thus modified independently of natural selection. Though this factor can operate but little in the vegetal world, and can play but a subordinate part in the lowest animal world; yet, seeing that all the active organs of all animals are subject to its influence, it has an immense sphere. The Duke of Argyll compares the claim made for this factor to "some bit of Bumbledom setting up for Home Rule—some parochial vestry claiming independence of a universal empire." But, far from this, the claim made for it is to an empire, less indeed than that of natural selection, and over a small part of which natural selection exercises concurrent power; but of which the independent part has an area that is immense.

It seems to me, then, that the Duke of Argyll is mistaken in four of the propositions contained in the passages I have quoted. The inheritance of acquired characters is disputed by biologists, though he thinks it is not. It is not true that "heredity is the central idea of natural selection." The statement that natural selection includes and covers all the causes which can possibly operate through inheritance, is quite erroneous. And if the inheritance of acquired characters is a factor at all, the dominion it rules over is not insignificant but vast.

Here I must break off, after dealing with a page and a half of the Duke of Argyll's article. A state of health which has prevented me from publishing anything since "The Factors of Organic Evolution," now nearly two years ago, prevents me from carrying the matter further. Could I have pursued the argument it would, I believe, have been practicable to show that various other positions taken up by the Duke of Argyll do not admit of effectual defence. But whether or not this is probable, the reader must be left to judge for himself. On one further point only will I say a word; and this chiefly because, if I pass it by, a mistaken impression of a serious kind may be diffused. The Duke of Argyll represents me as "giving up" the "famous phrase" "survival of the fittest," and wishing "to abandon it." He does this because I have pointed out that its words have connotations against which we must be on our guard, if we would avoid certain distortions of thought. With equal propriety he might say that an astronomer abandons the statement that the planets move in elliptic orbits, because he warns his readers that in the heavens there exist no such things as orbits, but that the planets sweep on through a pathless void, in directions perpetually changed by gravitation.

I regret that I should have had thus to dissent so entirely from various of the statements made, and conclusions drawn, by the Duke of Argyll, because, as I have already implied, I think he has done good service by raising afresh the question he has dealt with. Though the advantages which he hopes may result from the discussion are widely unlike the advantages which I hope may result from it, yet we agree in the belief that advantages may be looked for.

END OF VOL. I.

Minor punctuation errors have been changed without notice. Printer errors have been changed and are listed below. All other inconsistencies are as in the original.

The following changes have been made to the text:

Page 21: Was 'heterogeenity' (between man and man which are not regulated by civil and religious law. Moreover, it is to be observed that this increasing heterogeneity in the governmental appliances of each nation, has been accompanied by an)

Page 47: Was multipled (Medicines, special foods, better air, might in like manner be instanced as producing multiplied results. Now it needs only to consider that the many changes thus wrought by one force upon an adult organism, will be)

Page 59: Was Raffaelites (other. The influence which a new school of Painting—as that of the pre-Raphaelites—exercises upon other schools; the hints which all kinds of pictorial art are deriving from Photography; the complex results of)

Page 84: Was 'heretogeneity' (equilibrium. It will have a quite special liability to lapse into a non-homogeneous state. It will rapidly gravitate towards heterogeneity.)

Page 94: Was 'observedcoexistences' (physiology we are unable in many cases to trace this necessary correlation, and are obliged to base our conclusions upon observed coexistences, of which we do not understand the reason, but which we)

Page 97: Was 'Cirrhipoedia' (supposed that every eye must be external. Nevertheless it is a fact that there are creatures, as the Cirrhipedia, having eyes (not very efficient ones, it may be) deeply imbedded within the body. Again, a)

Page 108: Was 'prim facie' (Inquiring into the pedigree of an idea is not a bad means of roughly estimating its value. To have come of respectable ancestry, is prima facie evidence of worth in a belief as in a person; while to be)

Page 112: Was 'À fortioria' ("The spaces which precede or which follow simple nebulÆ," says Arago, "and a fortiori, groups of nebulÆ, contain generally few stars. Herschel found this rule to be invariable. Thus every time)

Page 124: Was 'irreconcileable' (stars like those which make up our own Milky Way, is totally irreconcilable with the facts—involves us in sundry absurdities. On the other hand, we see that the hypothesis of nebular condensation)

Page 140: Was 'some thing' (Mars a large error in my calculation had arisen from accepting Arago's statement of his density (0·95), which proves to be something like double what it should be. Here a curious incident may be named. When, in)

Page 216: Was 'representive' (less strange; and among the fish there exists a species of shark, which is the only living representative of a genus that flourished in early geologic epochs. If, now, the modern fossiliferous deposits of Australia)

Page 291: Was 'inbibe' (concentrated and purified nutriment, and distributing it among the component units; but these component units directly imbibe the unprepared nutriment, either from the digestive cavity or from one)

Page 306: Was 'whic hthey' (their units appear and disappear; are broad peculiarities which bodies-politic display in common with all living bodies; and in which they and living bodies differ from everything else. And on carrying out)

Page 359: Was 'not' (mind fitted neither for the kind of life led by the higher of the two races, nor for that led by the lower—a mind out of adjustment to all conditions of life. Contrariwise, we find that peoples of the same)

Page 393: Was 'parenthethic' (Returning from this parenthetic remark, we are concerned here chiefly to remember that, as said at the outset, there existed thirty years ago, no)

Page 411: Was 'hypertropic' (palsy, in a scarcely credible number of cases, are directly dependent on hypertrophic enlargement of the heart." And in other cases, asthma, dropsy, and epilepsy are caused. Now if a result of this)

Footnotes have been moved to end of the chapters. The page number for the correction on Page 140 is the original one, but the link points to the new location.