Modification of Germinal Constitution of Organisms 255 



It is clearly shown that in the germ cell before fertilization 

 there is a fundamental symmetry, polarity, from which there 

 arise during ontogeny the symmetries and arrangements 

 existing in the developing individual. This symmetry, 

 as far as there is any evidence, continues back through all 

 the cell generations which arise during gametogenesis, 

 and on the basis of what is known of development in the 

 germ cell, it seems to be a symmetry directly derived from 

 the parent zygote. In other words, in the continuity of 

 the germ cells from generation to generation, there is a 

 continuity of the symmetries and physical constitution 

 characteristic of the germinal material, a continuity of 

 germinal organization. It seems clearly established, espe- 

 cially by the work of Lillie and Morgan, that there is a 

 fundamental background, or matrix, in the germ cell in 

 which the original symmetries are expressed. For the pres- 

 ent the entire germ cell must be regarded as the germinal 

 material or germ plasm, and our problem in the investiga- 

 tion of the origin of germinal variations is to discover 

 by what methods changes in the germ cells are brought 

 about. This is one of the most difficult problems con- 

 fronting biologists, and one which is possibly incapable of 

 solution, at least in the near future, and perhaps may 

 forever remain unsolved. 



The chemical changes which go on in the living sub- 

 stance, especially those which follow in the metabolism of 

 organisms, have been roughly outlined, but these metabolic 

 processes, while they may result in the elaboration of pro- 

 ducts to be incorporated into or removed from the organism 

 in one way or another, do not possess any capacity for 

 carrying on their operations excepting in the living mass. 

 Moreover, we understand in a broad way the mechanical 



