EVOLUTION 111 



such influence possible." All the young were 

 black. The white body of the foster mother, 

 then, had no influence on the transplanted 

 egg cells, thus demonstrating in this respect 

 the independence of germ cells and somatic 

 cells in one individual. (Plate IV.) 



The evidence from experiments on the in- 

 heritance of mutilations, as well as on the 

 transmission of changes of a more normal 

 kind, and from observations on the effects 

 of a foster parent body on transplanted egg 

 cell, is thus unfavorable to the view that ac- 

 quired characters are heritable. If such char- 

 acters are inherited, it ought to be easy to 

 demonstrate the truth of this proposition, 

 but the fact that there is not a single un- 

 equivocal case in its favor, though the prop- 

 osition has been tested in many ways, is much 

 against it. The adverse evidence is all nega- 

 tive, and though conclusive negative evidence 

 is most difficult to obtain, that which is at 

 hand is so strongly negative that, inviting as 

 the proposition is, the inheritance of acquired 

 characters cannot be said to be supported by 

 present-day biological observation. 



That man is not an exception to the rule 

 just laid down seems at first sight startling, 



