Essays: Scientific, Political, & Speculative Part 21

In his article on Evolution in the _Encyclopaedia Britannica_, Professor Huxley writes as follows:--

"How far 'natural selection' suffices for the production of species remains 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 pa.s.sages 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 a.s.sumed 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.

NOTE.

[_The following pa.s.sages formed part of a preface to the small volume in which the foregoing essay re-appeared. I append them here as they cannot now be conveniently prefixed._]

Though the direct bearings of the arguments contained in this Essay are biological, the argument contained in its first half has indirect bearings upon Psychology, Ethics, and Sociology. My belief in the profound importance of these indirect bearings, was originally a chief prompter to set forth the argument; and it now prompts me to re-issue it in permanent form.

Though mental phenomena of many kinds, and especially of the simpler kinds, are explicable only as resulting from the natural selection of favourable variations; yet there are, I believe, still more numerous mental phenomena, including all those of any considerable complexity, which cannot be explained otherwise than as results of the inheritance of functionally-produced modifications. What theory of psychological evolution is espoused, thus depends on acceptance or rejection of the doctrine that not only in the individual, but in the successions of individuals, use and disuse of parts produce respectively increase and decrease of them.

Of course there are involved the conceptions we form of the genesis and nature of our higher emotions; and, by implication, the conceptions we form of our moral intuitions. If functionally-produced modifications are inheritable, then the mental a.s.sociations habitually produced in individuals by experiences of the relations between actions and their consequences, pleasurable or painful, may, in the successions of individuals, generate innate tendencies to like or dislike such actions.

But if not, the genesis of such tendencies is, as we shall see, not satisfactorily explicable.

That our sociological beliefs must also be profoundly affected by the conclusions we draw on this point, is obvious. If a nation is modified _en ma.s.se_ by transmission of the effects produced on the natures of its members by those modes of daily activity which its inst.i.tutions and circ.u.mstances involve; then we must infer that such inst.i.tutions and circ.u.mstances mould its members far more rapidly and comprehensively than they can do if the solo cause of adaptation to them is the more frequent survival of individuals who happen to have varied in favourable ways.

I will add only that, considering the width and depth of the effects which acceptance of one or other of these hypotheses must have on our views of Life, Mind, Morals, and Politics, the question--Which of them is true? demands, beyond all other questions whatever, the attention of scientific men.

After the above articles were published, I received from Dr. Downes a copy of a paper "On the Influence of Light on Protoplasm," written by himself and Mr. T.P. Blunt, M.A., which was communicated to the Royal Society in 1878. It was a continuation of a preceding paper which, referring chiefly to _Bacteria_, contended that--

"Light is inimical to, and under favourable conditions may wholly prevent, the development of these organisms."

This supplementary paper goes on to show that the injurious effect of light upon protoplasm results only in presence of oxygen. Taking first a comparatively simple type of molecule which enters into the composition of organic matter, the authors say, after detailing experiments:--

"It was evident, therefore, that _oxygen_ was the agent of destruction under the influence of sunlight."

And accounts of experiments upon minute organisms are followed by the sentence--

"It seemed, therefore, that in absence of an atmosphere, light failed entirely to produce any effect on such organisms as were able to appear."

They sum up the results of their experiments in the paragraph--

"We conclude, therefore, both from a.n.a.logy and from direct experiment, that the observed action on these organisms is not dependent on light _per se_, but that the presence of free oxygen is necessary; light and oxygen together accomplis.h.i.+ng what neither can do alone: and the inference seems irresistible that the effect produced is a gradual oxidation of the const.i.tuent protoplasm of these organisms, and that, in this respect, protoplasm, although living, is not exempt from laws which appear to govern the relations of light and oxygen to forms of matter less highly endowed. A force which is indirectly absolutely essential to life as we know it, and matter in the absence of which life has not yet been proved to exist, here unite for its destruction."

What is the obvious implication? If oxygen in presence of light destroys one of these minutest portions of protoplasm, what will be its effect on a larger portion of protoplasm? It will work an effect on the surface instead of on the whole ma.s.s. Not like the minutest ma.s.s made inert all through, the larger ma.s.s will be made inert only on its outside; and, indeed, the like will happen with the minutest ma.s.s if the light or the oxygen is very small in quant.i.ty. Hence there will result an envelope of changed matter, inclosing and protecting the unchanged protoplasm--there will result a rudimentary cell-wall.

FOOTNOTES:

[Footnote 41: It is probable that this shortening has resulted not directly but indirectly, from the selection of individuals which were noted for tenacity of hold; for the bull-dog's peculiarity in this respect seems due to relative shortness of the upper jaw, giving the underhung structure which, involving retreat of the nostrils, enables the dog to continue breathing while holding.]

[Footnote 42: 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. See _Animals and Plants under Domestication_ (first edition) Vol. i, p. 6; and _Origin of Species_ (sixth edition) p.

49.]

[Footnote 43: It is true that while not deliberately admitted by Mr.

Darwin, these effects are not denied by him. In his _Animals and Plants under Domestication_ (vol. ii, 281), he refers to certain chapters in the _Principles 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 a.s.sign 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.]

[Footnote 44: _Text-Book of Botany, &c._ by Julius Sachs. Translated by A. W. Bennett and W. T. T. Dyer.]

[Footnote 45: _A Manual of the Infusoria_, by W. Saville Kent. Vol. i, p. 232.]

[Footnote 46: _Ib._ Vol. i, p. 241.]

[Footnote 47: Kent, Vol. i, p. 56.]

[Footnote 48: _Ib._ Vol. i, p. 57.]

[Footnote 49: _The Elements of Comparative Anatomy_, by T. H. Huxley, pp. 7-9.]

[Footnote 50: _A Treatise on Comparative Embryology_, by F. M. Balfour, Vol. ii, chap. xiii.]

[Footnote 51: Sachs, p. 210.]

[Footnote 52: _Ibid._ pp. 83-4.]

[Footnote 53: _Ibid._ p. 185.]

[Footnote 54: _Ibid._ 80.]

[Footnote 55: Sachs, p. 83.]

[Footnote 56: _Ibid._ p. 147.]

[Footnote 57: _A Treatise on Comparative Embryology._ By Francis M.

Balfour, LL.D., F.R.S. Vol. ii, p. 343 (second edition).]

[Footnote 58: Balfour, l.c. Vol. ii, 400-1.]

[Footnote 59: Balfour, l.c. Vol. ii, p. 401.]

[Footnote 60: For a general delineation of the changes by which the development is effected, see Balfour, l.c. Vol. ii, pp. 401-4.]

[Footnote 61: _See_ Balfour, Vol. i, 149 and Vol. ii, 343-4.]

A COUNTER-CRITICISM.

[_First published in_ The Nineteenth Century_, for February,_ 1888.]