FACTS 205 



animal lives under conditions to which its species has long 

 been habituated, the [variations of the hereditary patri- 

 mony may be 1 considered null. Without appreciable 

 error we may admit that the hereditary patrimony of the 

 child-egg is identical with that of the parent-egg. 



But when important modifications are produced in the 

 life conditions of the species, some new adaptation will be 

 necessary under pain of death. The animal, therefore, 

 if it does not die, will vary by functional assimilation, that 

 is, certain of its constituent parts will be developed more 

 than others and these, on the contrary, will grow less. 

 These variations in the general structure of a being are 

 commonly called acquired characters. 



In reality, in strictness of speech, we ought to say that 

 every character is an acquired character, for, no matter 

 how small the variations in the educative factors B may 

 be, they are never null. We must not forget our symbolic 

 formula 



A n _, + (A H _! x E n _ i )=A n . 



But, under conditions considered normal for a species 

 because of prolonged habit, the variations may be neglected, 

 since the children are always, at any determined age, very 

 nearly what their parents were at the same age. In other 

 words, the series of the factors B t , B 2 , . . . B n , is very 

 nearly the same for the children as it was for the parents. 



In cases where new factors B 1 are introduced into the 

 education of the children, these, if they do not die, will 

 adapt themselves by functional assimilation ; and by 

 such adaptation they become different from their parents. 



The problem of the heredity of acquired characters is 

 the following : 



1 These B factors may be anything at all, sickness, mutilation, 

 passage from land life to aquatic life, etc. Our reasoning is general. 



