ATAVISM : MUTILATIONS 153 



surrounding conditions are unaltered the idioplasm is unchanged ; 

 alter these conditions and the idioplasm is liable to variation in 

 constitution. 



Atavism. Lastly, in regard to atavism and reversionary 

 degeneration of the cells of the individual, this conception of 

 the idioplasm with attached side-chains, which are more firmly 

 or more loosely attached, affords a perfectly adequate explana- 

 tion. The more advanced the organism, the greater number of 

 these attached side-chains ; the more recent the attachment of 

 a side-chain, the more unstable that attachment. As a conse- 

 quence, any profound disturbance will, according to its intensity, 

 tend to cause the loosening and removal of the more unstable 

 side-chains, in general in the order of their stability of attach- 

 ment. And as the structure of the individual and of the 

 individual cells is the expression of the constitution of the 

 idioplasm, of the germinal idioplasm, and of the idioplasm of the 

 individual cells, so according to the intensity of the disturbance 

 will there be greater or less reversion to an earlier stage in the 

 developmental history. 



Let us now apply this theory to those special problems 

 which I have referred to as being of peculiar interest to us as 

 medical men. Can acquired defects be transmitted ? In 

 seeking to answer this question, at least three orders of pheno- 

 mena have to be recognized and distinguished. These are : 



1. The Non-Inheritance of Acquired Mutilations. To these 

 I have already referred. We cannot conceive of the direct 

 transmission of identical lesions of this order from parent to 

 offspring. At most we can conceive of the possibility of indirect 

 effect where the mutilation is extensive or affects organs playing 

 an important part in general nutrition. If there is impoverished 

 general nutrition we can understand that this can affect the 

 germ cells along with the other cells of the organism, that the 

 lack of due assimilation or the excess of sundry internal secretions 

 which, in consequence of lowered general metabolism, have been 

 imperfectly neutralized, by telling upon the blood and lymph, 

 may lead to modification of the idioplasm of those germ cells, 

 with the possible resultant imperfections in the growth of the 

 fertilized germ, everything depending here upon the combination 

 of the modified germ plasm of the mutilated individual with 

 that of the other parent. If the number of molecules of this 



