Chapter 6

But gradually with that increase of activity which we see on ascending to successively higher grades of animals, and especially with that increased complexity of life which we also see, there came more and more into play as a factor, the inheritance of those modifications of structure caused by modifications of function. Eventually, among creatures of high organization, this factor became an important one; and I think there is reason to conclude that, in the case of the highest of creatures, civilized men, among whom the kinds of variation which affect survival are too multitudinous to permit easy selection of any one, and among whom survival of the fittest is greatly interfered with, it has become the chief factor: such aid as survival of the fittest gives, being usually limited to the preservation of those in whom the totality of the faculties has been most favourably moulded by functional changes.

Of course this sketch of the relations among the factors must be taken as in large measure a speculation. We are now too far removed from the beginnings of life to obtain data for anything more than tentative conclusions respecting its earliest stages; especially in the absence of any clue to the mode in which multiplication, first agamogenetic and then gamogenetic, was initiated. But it has seemed to me not amiss to present this general conception, by way of showing how the deductive interpretation harmonizes with the several inferences reached by induction.

In his article on Evolution in theEncyclopædia Britannica, Professor Huxley writes as follows:—

“How far 'natural selection' suffices for the production of speciesremains to be seen. Few can doubt that, if not the whole cause, it is a very important factor in that operation.... On the evidence of palaeontology, the evolution of many existing forms of animal life from their predecessors is no longer an hypothesis, but an historical fact; it is only the nature of the physiological factors to which that evolution is due which is still open to discussion.”

With these passages I may fitly join a remark made in the admirable address Prof. Huxley delivered before unveiling the statue of Mr. Darwin in the Museum at South Kensington. Deprecating the supposition that an authoritative sanction was given by the ceremony to the current ideas concerning organic evolution, he said that “science commits suicide when it adopts a creed.”

Along with larger motives, one motive which has joined in prompting the foregoing articles, has been the desire to point out that already among biologists, the beliefs concerning the origin of species have assumed too much the character of a creed; and that while becoming settled they have been narrowed. So far from further broadening that broader view which Mr. Darwin reached as he grew older, his followers appear to have retrograded towards a more restricted view than he ever expressed. Thus there seems occasion for recognizing the warning uttered by Prof. Huxley, as not uncalled for.

Whatever may be thought of the arguments and conclusions set forth in this article and the preceding one, they will perhaps serve to show that it is as yet far too soon to close the inquiry concerning the causes of organic evolution.

2.Though Mr. Darwin approved of this expression and occasionally employed it, he did not adopt it for general use; contending, very truly, that the expression Natural Selection is in some cases more convenient. SeeAnimals and Plants under Domestication(first edition) Vol. i, p. 6; andOrigin of Species(sixth edition) p. 49.

3.It is true that while not deliberately admitted by Mr. Darwin, these effects are not denied by him. In hisAnimals and Plants under Domestication(vol. ii, 281), he refers to certain chapters in thePrinciples of Biology, in which I have discussed this general inter-action of the medium and the organism, and ascribed certain most general traits to it. But though, by his expressions, he implies a sympathetic attention to the argument, he does not in such way adopt the conclusion as to assign to this factor any share in the genesis of organic structures—much less that large share which I believe it has had. I did not myself at that time, nor indeed until quite recently, see how extensive and profound have been the influences on organization which, as we shall presently see, are traceable to the early results of this fundamental relation between organism and medium. I may add that it is in an essay on “Transcendental Physiology,” first published in 1857, that the line of thought here followed out in its wider bearings, was first entered upon.

4.Text-Book of Botany, &c. by Julius Sachs. Translated by A. W. Bennett and W. T. T. Dyer.

5.A Manual of the Infusoria, by W. Saville Kent. Vol. i, p. 232.

6.Ib.Vol. i, p. 241.

7.Kent, Vol. i, p. 56.

8.Ib.Vol. i, p. 57.

9.The Elements of Comparative Anatomy, by T. H. Huxley, pp. 7-9.

10.A Treatise on Comparative Embryology, by F. M. Balfour, Vol. ii, chap. xiii.

11.Sachs, p. 210.

12.Ibid.pp. 83-4.

13.Ibid.p. 185.

14.Ibid.p. 80.

15.Sachs, p. 83.

16.Ibid.p. 147.

17.A Treatise on Comparative Embryology.By Francis M. Balfour,LL.D., F.R.S.Vol. ii, p. 343 (second edition).

18.Balfour, l.c. Vol. ii, 400-1.

19.Balfour, l.c. Vol. ii, p. 401.

20.For a general delineation of the changes by which the development is effected, see Balfour, l.c. Vol. ii, pp. 401-4.

21.SeeBalfour, Vol. i, 149 and Vol. ii, 313-4.

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