A frequent and a just objection to the Lamarckian hypothesis of the trans.m.u.tation of species is based upon the absence of transitional forms between many species. But against the Darwinian hypothesis this argument has no force. Indeed, one of the most valuable and suggestive parts of Mr. Darwin"s work is that in which he proves, that the frequent absence of transitions is a necessary consequence of his doctrine, and that the stock whence two or more species have sprung, need in no respect be intermediate between these species. If any two species have arisen from a common stock in the same way as the carrier and the pouter, say, have arisen from the rock-pigeon, then the common stock of these two species need be no more intermediate between the two than the rock-pigeon is between the carrier and pouter. Clearly appreciate the force of this a.n.a.logy, and all the arguments against the origin of species by selection, based on the absence of transitional forms, fall to the ground. And Mr. Darwin"s position might, we think, have been even stronger than it is if he had not embarra.s.sed himself with the aphorism, "_Natura non facit saltum_," which turns up so often in his pages. We believe, as we have said above, that Nature does make jumps now and then, and a recognition of the fact is of no small importance in disposing of many minor objections to the doctrine of trans.m.u.tation.
But we must pause. The discussion of Mr. Darwin"s arguments in detail would lead us far beyond the limits within which we proposed, at starting, to confine this article. Our object has been attained if we have given an intelligible, however brief, account of the established facts connected with species, and of the relation of the explanation of those facts offered by Mr. Darwin to the theoretical views held by his predecessors and his contemporaries, and, above all, to the requirements of scientific logic. We have ventured to point out that it does not, as yet, satisfy all those requirements; but we do not hesitate to a.s.sert that it is as superior to any preceding or contemporary hypothesis, in the extent of observational and experimental basis on which it rests, in its rigorously scientific method, and in its power of explaining biological phaenomena, as was the hypothesis of Copernicus to the speculations of Ptolemy. But the planetary orbits turned out to be not quite circular after all, and, grand as was the service Copernicus rendered to science, Kepler and Newton had to come after him. What if the orbit of Darwinism should be a little too circular? What if species should offer residual phaenomena, here and there, not explicable by natural selection? Twenty years hence naturalists may be in a position to say whether this is, or is not, the case; but in either event they will owe the author of "The Origin of Species" an immense debt of grat.i.tude. We should leave a very wrong impression on the reader"s mind if we permitted him to suppose that the value of that work depends wholly on the ultimate justification of the theoretical views which it contains. On the contrary, if they were disproved to-morrow, the book would still be the best of its kind--the most compendious statement of well-sifted facts bearing on the doctrine of species that has ever appeared. The chapters on Variation, on the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection of the Geological Record, on Geographical Distribution, have not only no equals, but, so far as our knowledge goes, no compet.i.tors, within the range of biological literature. And viewed as a whole, we do not believe that, since the publication of Von Baer"s Researches on Development, thirty years ago, any work has appeared calculated to exert so large an influence, not only on the future of Biology, but in extending the domination of Science over regions of thought into which she has, as yet, hardly penetrated.
FOOTNOTES:
[61] On the Osteology of the Chimpanzees and Orangs: Transactions of the Zoological Society, 1858.
[62] Colonel Humphreys" statements are exceedingly explicit on this point:--"When an Ancon ewe is impregnated by a common ram, the increase resembles wholly either the ewe or the ram. The increase of the common ewe impregnated by an Ancon ram follows entirely the one or the other, without blending any of the distinguishing and essential peculiarities of both. Frequent instances have happened where common ewes have had twins by Ancon rams, when one exhibited the complete marks and features of the ewe, the other of the ram. The contrast has been rendered singularly striking, when one short-legged and one long-legged lamb, produced at a birth, have been seen sucking the dam at the same time."--_Philosophical Transactions_, 1813, Pt. I., pp. 89, 90.
[63] Recent investigations tend to show that this statement is not strictly accurate.--1870.
[64] See Phil. Zoologique, vol. i. p. 222, et seq.
XIII.
CRITICISMS ON "THE ORIGIN OF SPECIES."
1. UEBER DIE DARWIN"SCHE SCHoPFUNGSTHEORIE; EIN VORTAG, VON A.
KoLLIKER. Leipzig, 1864.
2. EXAMINATION DU LIVRE DE M. DARWIN SUR L"ORIGINE DES ESPeCES.
PAR P. FLOURENS. Paris, 1864.
In the course of the present year [1864] several foreign commentaries upon Mr. Darwin"s great work have made their appearance. Those who have perused that remarkable chapter of the "Antiquity of Man," in which Sir Charles Lyell draws a parallel between the development of species and that of languages, will be glad to hear that one of the most eminent philologers of Germany, Professor Schleicher, has, independently, published a most instructive and philosophical pamphlet (an excellent notice of which is to be found in the _Reader_, for February 27th of this year) supporting similar views with all the weight of his special knowledge and established authority as a linguist. Professor Haeckel, to whom Schleicher addresses himself, previously took occasion, in his splendid monograph on the _Radiolaria_,[65] to express his high appreciation of, and general concordance with, Mr. Darwin"s views.
But the most elaborate criticisms of the "Origin of Species" which have appeared are two works of very widely different merit, the one by Professor Kolliker, the well-known anatomist and histologist of Wurzburg; the other by M. Flourens, Perpetual Secretary of the French Academy of Sciences.
Professor Kolliker"s critical essay "Upon the Darwinian Theory" is, like all that proceeds from the pen of that thoughtful and accomplished writer, worthy of the most careful consideration. It comprises a brief but clear sketch of Darwin"s views, followed by an enumeration of the leading difficulties in the way of their acceptance; difficulties which would appear to be insurmountable to Professor Kolliker, inasmuch as he proposes to replace Mr. Darwin"s Theory by one which he terms the "Theory of Heterogeneous Generation." We shall proceed to consider first the destructive, and secondly, the constructive portion of the essay.
We regret to find ourselves compelled to dissent very widely from many of Professor Kolliker"s remarks; and from none more thoroughly than from those in which he seeks to define what we may term the philosophical position of Darwinism.
"Darwin," says Professor Kolliker, "is, in the fullest sense of the Word, a Teleologist. He says quite distinctly (First Edition, pp.
199, 200) that every particular in the structure of an animal has been created for its benefit, and he regards the whole series of animal forms only from this point of view."
And again:
"7. The teleological general conception adopted by Darwin is a mistaken one.
"Varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent.
"The a.s.sumption that an organism exists only on account of some definite end in view, and represents something more than the incorporation of a general idea, or law, implies a one-sided conception of the universe. a.s.suredly, every organ has, and every organism fulfils, its end, but its purpose is not the condition of its existence. Every organism is also sufficiently perfect for the purpose it serves, and in that, at least, it is useless to seek for a cause of its improvement."
It is singular how differently one and the same book will impress different minds. That which struck the present writer most forcibly on his first perusal of the "Origin of Species" was the conviction that Teleology, as commonly understood, had received its deathblow at Mr.
Darwin"s hands. For the teleological argument runs thus: an organ or organism (A) is precisely fitted to perform a function or purpose (B); therefore it was specially constructed to perform that function. In Paley"s famous ill.u.s.tration, the adaptation of all the parts of the watch to the function, or purpose, of showing the time, is held to be evidence that the watch was specially contrived to that end; on the ground, that the only cause we know of, competent to produce such an effect as a watch which shall keep time, is a contriving intelligence adapting the means directly to that end.
Suppose, however, that any one had been able to show that the watch had not been made directly by any person, but that it was the result of the modification of another watch which kept time but poorly; and that this again had proceeded from a structure which could hardly be called a watch at all--seeing that it had no figures on the dial and the hands were rudimentary; and that going back and back in time we came at last to a revolving barrel as the earliest traceable rudiment of the whole fabric. And imagine that it had been possible to show that all these changes had resulted, first, from a tendency of the structure to vary indefinitely; and secondly, from something in the surrounding world which helped all variations in the direction of an accurate time-keeper, and checked all those in other directions; then it is obvious that the force of Paley"s argument would be gone. For it would be demonstrated that an apparatus thoroughly well adapted to a particular purpose might be the result of a method of trial and error worked by unintelligent agents, as well as of the direct application of the means appropriate to that end, by an intelligent agent.
Now it appears to us that what we have here, for ill.u.s.tration"s sake, supposed to be done with the watch, is exactly what the establishment of Darwin"s Theory will do for the organic world. For the notion that every organism has been created as it is and launched straight at a purpose, Mr. Darwin subst.i.tutes the conception of something which may fairly be termed a method of trial and error. Organisms vary incessantly; of these variations the few meet with surrounding conditions which suit them and thrive; the many are unsuited and become extinguished.
According to Teleology, each organism is like a rifle bullet fired straight at a mark; according to Darwin, organisms are like grapeshot of which one hits something and the rest fall wide.
For the teleologist an organism exists because it was made for the conditions in which it is found; for the Darwinian an organism exists because, out of many of its kind, it is the only one which has been able to persist in the conditions in which it is found.
Teleology implies that the organs of every organism are perfect and cannot be improved; the Darwinian theory simply affirms that they work well enough to enable the organism to hold its own against such compet.i.tors as it has met with, but admits the possibility of indefinite improvement. But an example may bring into clearer light the profound opposition between the ordinary teleological, and the Darwinian, conception.
Cats catch mice, small birds and the like, very well. Teleology tells us that they do so because they were expressly constructed for so doing--that they are perfect mousing apparatuses, so perfect and so delicately adjusted that no one of their organs could be altered, without the change involving the alteration of all the rest. Darwinism affirms, on the contrary, that there was no express construction concerned in the matter; but that among the mult.i.tudinous variations of the Feline stock, many of which died out from want of power to resist opposing influences, some, the cats, were better fitted to catch mice than others, whence they throve and persisted, in proportion to the advantage over their fellows thus offered to them.
Far from imagining that cats exist _in order_ to catch mice well, Darwinism supposes that cats exist _because_ they catch mice well--mousing being not the end, but the condition, of their existence.
And if the cat-type has long persisted as we know it, the interpretation of the fact upon Darwinian principles would be, not that the cats have remained invariable, but that such varieties as have incessantly occurred have been, on the whole, less fitted to get on in the world than the existing stock.
If we apprehend the spirit of the "Origin of Species" rightly, then, nothing can be more entirely and absolutely opposed to Teleology, as it is commonly understood, than the Darwinian Theory. So far from being a "Teleologist in the fullest sense of the word," we should deny that he is a Teleologist in the ordinary sense at all; and we should say that, apart from his merits as a naturalist, he has rendered a most remarkable service to philosophical thought by enabling the student of Nature to recognise, to their fullest extent, those adaptations to purpose which are so striking in the organic world, and which Teleology has done good service in keeping before our minds, without being false to the fundamental principles of a scientific conception of the universe. The apparently diverging teachings of the Teleologist and of the Morphologist are reconciled by the Darwinian hypothesis.
But leaving our own impressions of the "Origin of Species," and turning to those pa.s.sages specially cited by Professor Kolliker, we cannot admit that they bear the interpretation he puts upon them. Darwin, if we read him rightly, does _not_ affirm that every detail in the structure of an animal has been created for its benefit. His words are (p. 199):--
"The foregoing remarks lead me to say a few words on the protest lately made by some naturalists against the utilitarian doctrine that every detail of structure has been produced for the good of its possessor. They believe that very many structures have been created for beauty in the eyes of man, or for mere variety. This doctrine, if true, would be absolutely fatal to my theory--yet I fully admit that many structures are of no direct use to their possessor."
And after sundry ill.u.s.trations and qualifications, he concludes (p.
200):--
"Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form--either directly, or indirectly, through the complex laws of growth."
But it is one thing to say, Darwinically, that every detail observed in an animal"s structure is of use to it, or has been of use to its ancestors; and quite another to affirm, teleologically, that every detail of an animal"s structure has been created for its benefit. On the former hypothesis, for example, the teeth of the foetal _Balaena_ have a meaning; on the latter, none. So far as we are aware, there is not a phrase in the "Origin of Species," inconsistent with Professor Kolliker"s position, that "varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent."
On the contrary, Mr. Darwin writes (Summary of Chap. V.):--
"Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to a.s.sign any reason why this or that part varies more or less from the same part in the parents.... The external conditions of life, as climate and food, &c. seem to have induced some slight modifications. Habit, in producing const.i.tutional differences, and use, in strengthening, and disuse, in weakening and diminishing organs, seem to have been more potent in their effects."
And finally, as if to prevent all possible misconception, Mr. Darwin concludes his Chapter on Variation with these pregnant words:--
"Whatever the cause may be of each slight difference in the offspring from their parents--and a cause for each must exist--it is the steady acc.u.mulation, through natural selection of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure, by which the innumerable beings on the face of the earth are enabled to struggle with each other, and the best adapted to survive."
We have dwelt at length upon this subject, because of its great general importance, and because we believe that Professor Kolliker"s criticisms on this head are based upon a misapprehension of Mr. Darwin"s views--substantially they appear to us to coincide with his own. The other objections which Professor Kolliker enumerates and discusses are the following:[66]--
"1. No transitional forms between existing species are known; and known varieties, whether selected or spontaneous, never go so far as to establish new species."
To this Professor Kolliker appears to attach some weight. He makes the suggestion that the short-faced tumbler pigeon may be a pathological product.
"2. No transitional forms of animals are met with among the organic remains of earlier epochs."
Upon this, Professor Kolliker remarks that the absence of transitional forms in the fossil world, though not necessarily fatal to Darwin"s views, weakens his case.
"3. The struggle for existence does not take place."
To this objection, urged by Pelzeln, Kolliker, very justly, attaches no weight.