578 



NATURE 



[January 21, 19 15 



earliest of our ancestors) embodied in some sense or 

 other all the potentialities, for better or for worse, 

 that are realised before us at this moment in the 

 American Association for the Advancement of Science. 

 But if we ask ourselves exactly what we mean by 

 this we discover our total inability to answer in more 

 intelligible terms. We cannot, it is true, even if we 

 would, conquer the temptation now and then to spread 

 the wings of our imagination in the thin atmosphere 

 of these upper regions ; and this is no doubt an excel- 

 lent tonic for the cerebrum provided we cherish no 

 illusions as to what we are about. No embryologist, 

 for example, can help puzzling over what I have 

 called the problem of the microcosm ; but he should 

 be perfectly well aware that in striving to picture to 

 his imagination the ultimate organisation of the ^^%i 

 of the embryological germ, that is actually in his 

 hands for observation and experiment, he is perilously 

 near to the habitat of the mystic and the 

 transcendentalist. The student of evolution is far 

 over the frontier of that forbidden land, in any present 

 attack upon the corresponding problem of the 

 macrocosm ; for the primordial Amoeba, the evolu- 

 tionary germ, is inconceivably far out of our reach, 

 hidden behind the veil of a past the beginnings of 

 which lie wholly beyond our ken. And why, after all, 

 should we as yet attempt the exploration of a region 

 which still remains so barren and remote? Surely 

 not for the lack of accessible fields of genetic research 

 that are fertile and varied enough to reward our best 

 efforts, as no one has more forcibly urged or more 

 brilliantly demonstrated by his own example than 

 Prof. Bateson himself. 



Perhaps it would be the part of discretion to go no 

 further. But the remarkable questions that Prof. 

 Bateson has raised concerning the nature of evolution 

 leave almost untouched the equally momentous 

 problem as to what has guided its actual course. In 

 approaching my close I shall be bold enough to 

 venture a step in this direction, even one that will 

 bring us upon the hazardous ground of organic 

 adaptations and the theory of natural selection. I 

 need not say that this subject is beset by intricate 

 and baffling difficulties which have made it a veritable 

 bone of contention among naturalists in recent years. 

 In our attempts to meet them we have gone to some 

 curious extremes. On the one hand, some naturalists 

 have in effect abandoned the problem, cutting the 

 Gordian knot with the conclusion that the power of 

 adaptation is something given with organisation itself 

 and as such offers a riddle that is for the present 

 insoluble. In another direction we find attempts to 

 take the problem in flank, to restate it, to ignore it — 

 sometimes, it would almost seem to argue it out of 

 existence. It has been urged in a recent valuable 

 work — by an author, I hasten to say, who fully 

 accepts both the mechanistic philosophy and the prin- 

 ciple of selection — that fitness is a reciprocal relation, 

 involving the environment no less than the organism. 

 This is both a true and a suggestive thought ; but 

 does it not leave the naturalist floundering amid the 

 same old quicksands? The historical problem with 

 which he has to deal must be grappled at closer 

 quarters. He is everywhere confronted with specific 

 devices in the organism that must have arisen long 

 after the conditions of environment to which they 

 adjusted. Animals that live in water are provided 

 with gills. Were this all we could probably muddle 

 along with the notion that gills are no more than 

 lucky accidents. But we encounter a sticking point in 

 the fact that gills are so often accompanied by a 

 variety of ingenious devices, such as reservoirs, tubes, 

 valves, pumps, strainers, scrubbing brushes, and the 

 like, that are obviously tributary to the main function 



NO. 2360, VOL. 94] 



of breathing. Given water, asks the naturalist, how 

 has all this come into existence and been perfected? 

 The question is an inevitable product of our common 

 sense. The metaphvsician, I think, is not he who 

 asks but he who would suppress it. 



For all that it would seem that some persons find 

 the very word adaptation of too questionable a repu- 

 tation for mention in polite scientific society. Allow 

 me to illustrate by a leaf taken from my own note- 

 book. I once ventured to publish a small experi- 

 mental work on the movements of the fresh-water 

 Hydra with respect to light. What was my surprise 

 to receive a reproof from a friendly critic, because I 

 had not been content with an objective description of 

 the movements but had also been so indiscreet as to 

 emphasise their evident utility to the animal. I was 

 no doubt too young then — I fear I am too old now — 

 to comprehend in what respect I had sinned against 

 the light. That was long ago. I will cite a more 

 recent example from a public discussion on adaptation 

 that took place before the American Society of 

 Naturalists a year or two since. "The dominance of 

 the concept of adaptation," said one naturalist, 

 " which now distinguishes our science from the non- 

 biological ones, is related to the comparatively j'outh- 

 ful stage of development so far attained by biology, 

 and not to any observed character in the living objects 

 with which we deal.'' Here, we almost seem to catch 

 an echo from the utterances of a certain sect of self- 

 stvled " scientists " who love to please themselves 

 with the quaint fancy that physical disease is but one 

 of the "errors of mortal mind." 



Now, it is undoubtedly true that many adaptations, 

 to cite Prof. Bateson once more, are " not in practice 

 a very close fit." Even the eye, as Helmholtz long 

 ago taught us, has some defects as an optical instru- 

 ment ; nevertheless, it enables us to see well enough 

 to discern some food for reflection concerning adapta- 

 tions among living things. And it is my impression 

 that efforts to explain adaptations are likely to con- 

 tinue for the reason that naturalists as a body, perhaps 

 influenced by Huxlev's definition of science, have an 

 obstinate habit of clinging to their common sense. 



At the present day there is no longer the smallest 

 doubt of the great outstanding fact that many complex 

 structural adaptations — it would probably be correct 

 to say all such — have not come into existence at a 

 single stroke but have moved forward step by step 

 to the attainment of their full degree of perfection. 

 What has dominated the direction and final outcome 

 of such advancing lines? We cannot yet answer this 

 question with any degree of assurance ; but pro- 

 crastinate as we mav, it must in the end squarely be 

 faced. We have seen one theory after another forced 

 back within narrower lines or crumbling away before 

 the adverse fire of criticism. I will not pause to 

 recount the heavy losses that must be placed to the 

 account of sexual selection, of neo-Lamarckism, of 

 orthogenesis. Some naturalists, no doubt, would 

 assign a prominent place in this list of casualties to 

 natural selection; but probably there are none who 

 would hold that it has been destroyed utterly. The 

 crux lies in the degree of its efficacy. Stated as an 

 irreducible minimum the survival of the fit is an 

 evident fact. Individuals that are unfitted to live, or 

 to reproduce, leave few or no descendants — so much, 

 at least, must be admitted by all. But does this 

 colourless and trite conclusion end the matter or 

 adequatelv place before us the significance of the 

 facts ? Jiist here lies the whole issue. Does destruc- 

 tion of the unfit accomplish no other result than to 

 maintain the status quo, or has it conditioned the 

 direction of progress? Accepting the second of these 

 alternatives, Darwin went so far as to assign to it a 



