DEVELOPMENT BY SMALL STEPS. 22Q 



haps a constantly changing one, a change in func- 

 tion accompanying a change in form. In a similar 

 manner Darwin has treated other cases of this kind 

 which have been suggested, and has had remarkable 

 success in showing that it is possible to understand 

 how by a change of function natural selection might 

 extend to organs seemingly of no use except in their 

 highly developed condition. His explanations are, 

 of course, plainly hypothetical. Even granting them 

 sufficient, it still appears that the very first beginning 

 of such organs is difficult to account for. In the 

 case given it may well be that, after the horny pro- 

 jections had become large enough and strong enough 

 to aid materially in seizing and tearing food, they 

 would be preserved by natural selection ; but the 

 ordinary variations are too small to account for the 

 sudden appearance even of such protuberances. It 

 is altogether too much for one's credulity to be- 

 lieve that the presence of one or two accidental 

 roughenings in the mouths of one or two animals 

 would be of enough advantage to lead to the survival 

 of these individuals and the extinction of others 

 which did not chance to possess them. If we can 

 assume that at some time in the past there was a 

 sudden great variation in the mouths of the whales' 

 ancestors, affecting many individuals at once, the 

 solution offered by Darwin may be accepted ; but 

 so long as it is only scattered, indefinite, minute 

 variations which natural selection has to work upon, 

 the difficulty herein lying is very great. 



But even after the beginning of organs is ac- 

 counted for, it is equally difficult to see how they 



