No. 554] ADAPTATION AND THE PHYSIOLOGIST 91 



expression in ordinary language, of the apparent com- 

 plexities of evolution. I avow myself as a physiologist to 

 be a follower of Darwin, admiring his methods of careful 

 experiment and observation, his long cogitations, and 

 with confidence in the soundness of his judgment. There 

 has been a tendency of recent years in certain quarters 

 to belittle his work, to make fun of his conclusions, to 

 deny that evolution has been a slow and steady continu- 

 ous process, as the rocks show, and to assert that it has 

 taken place by a hop, skip and a jump, and that it would 

 have taken place anyway without natural selection. 

 Physics and chemistry have attempted to express the 

 physical world in terms of matter and energy, and many 

 biologists are attempting to extend this method to the 

 living world. While this is a necessary and admirable 

 thing to do, it must not be forgotten that in doing so 

 they are neglecting the main fact of life, consciousness, 

 and that the phenomena of life can not be accounted for 

 if this is neglected. It is obvious, too, that the physicist, 

 with his present conception of matter and energy, is mak- 

 ing as great a mistake in neglecting the psychical side of 

 matter as the biologist would make if he neglected the 

 physical side. For the psychical, like the physical, must 

 be due to the properties of the atoms, or at least is asso- 

 ciated always with them. For the atoms are the same in 

 living and lifeless, their properties are inherent in them 

 and can not be taken away and added to them as if they 

 were wagons, which changed horses, as Du Bois Ray- 

 mond has put it. 



It is my opinion that physiology comes powerfully to 

 the support of Darwin's conclusions ; that it shows clearly 

 that there are no such tilings as independently variable, 

 unit characters ; that a jump is a physiological impossi- 

 bility; and that most so-called mutations are in reality 

 reversions, as Darwin thought ; and in this position physi- 

 ology i s , I believe, supported by paleontology. 



But while accepting many of Darwin's conclusions, we 

 must all admit that many phenomena are very hard 



