PROGRESS IN ZOOLOGY — WILSON. 405 



conclusion that the power of adaptation is something given Avith 

 organization itself and as such offers a riddle that is for the present 

 insoluble. In another direction we find attempts to take the prob- 

 lem 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 — hj an author, I 

 hasten to say, who fully accepts both the mechanistic philosophy 

 and the principle of selection — that fitness is a reciprocal relation, 

 involving tlie 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 are 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 tribu- 

 tary to the main function of breathing. Given water, asks the nat- 

 uralist, how has all this come into existence and been perfected? 

 The question is an inevitable product of our common sense. The 

 metaphysician, I think, is not he who asks but he who would sup- 

 press it. 



For all that, it would seem that some persons find the very word 

 adaptation of too questionable a reputation for mention in polite 

 scientific society. Allow me to illustrate by a leaf taken from my 

 own notebook. I once ventured to publish a small experimental 

 work on the movements of the fresh-water hydra with respect to 

 light. \^liat 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 emphasize 

 their evident utility to the animal. I was no doubt too 3^oung 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 tlie 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 youthful 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- 

 styled "scientists" who love to please themselves with the quaint 



