426 F. A. BATHER [december 



through selection will be proportional to the number of variations in 

 the direction of progress. If variations be governed by the laws of 

 chance alone, that number must be less than when variations are 

 determined in the direction of the environment by the inheritance of 

 modification. Fitness would be reached more readily if modifications 

 were inherited. 



The second consideration is more subtle. It is a question whether 

 education or the action of the external world can add anything to the 

 nature of the organism, whether it does not merely unfold and develop 

 the original nature. Here is the old difference between development 

 by epigenesis and by evolution. Dr. Brooks makes a compromise 

 that seems consistent with common sense. The organism, he says, 

 would not develop without the education, but the character of the 

 development is due to its original nature (p. 15). No vital action 

 takes place without a stimulus ; but the stimulus is one thing, the 

 character of the action is another, and is dependent on the nature of 

 the organism. Thus in ontogeny each change may be called forth by 

 some mechanical stimulus, either within the body or without, and yet 

 the nature of the whole may depend on the nature of the germ 

 (p. 59). "External conditions press the button, but it takes all the 

 inherent potency of living matter to do the rest" (p. 61). 



An ingenious application of this conception may be noted in pass- 

 ing. It is that " organs once adjusted to the external world may, 

 after the adjustment has lost its meaning, be still retained, because 

 they furnish physiological stimuli, which excite developmental 

 changes in the organic mechanism" (p. 10). Thus Dr. Brooks 

 accounts for the retention of so-called rudimentary organs and recapitu- 

 latory stages. 



But we have to see how the conception affects the problem of 

 fitness. If it be correct, if, in other words, nurture adds nothing to 

 nature, then there is nothing to be inherited. But the problem does 

 not become easier of solution. It consists of two parts : the adapta- 

 bility of the individual ; and the adaptation of the race. The adapta- 

 bility of the individual resolves itself into the adaptability of 

 protoplasm, and none is so bold as to say he knows the explan- 

 ation of this. Turning to the adaptation of the race ; each new 

 germ would, on this conception, be similar in all respects to the 

 primordial protoplasm, being in fact nothing but an extended part 

 thereof, but gradually becoming more and more gifted with the power 

 of growing into a being modified in accordance with its environment. 

 But it is very difficult to see why or how it should obtain this power, 

 except through education. The faculty of being educated was, we 

 may suppose, present in the original protoplasm ; and it has gone on 

 being educated ever since. Some portions of it, from one cause or 

 another, did not respond so readily to education, and they have been 

 expelled in consequence ; that is what we mean by natural selection. 



