The Process of Heredity 561 



ing factors of a similarity of process are, first a similarity of ger- 

 minal substance, and second a similarity of external conditions. 

 Whether these determining factors are of equal or unequal potency 

 is a question that scarcely requires an answer. Neither is opera- 

 tive without the other, and in this sense they are of equal potency. 

 Any change in either will produce a change in the process of 

 heredity, and to that extent a dissimilarity between parent and 

 offspring, which means a failure to accomplish an ideal heredity. 

 Ideal heredity can never be realized because of the inherent vari- 

 ability of things. No two organisms ever start out from identical 

 germ cells, nor do they develop under identical external conditions. 

 Therefore a striking degree of similarity between parent and 

 offspring is all that is ever realized. 



If then we admit that the essence of heredity is the similarity 

 of developmental process, we must come to the conclusion that 

 the study of development and of heredity are identical, except in 

 that the latter is a comparative study, the object of which is to 

 determine to what extent the developmental phases of offspring 

 resemble those of parent, or as in the present work to determine 

 what relative influence is to be attributed to either parent. 



Heredity has long been studied as a static condition instead of 

 a dynamic process, and it is the hope of the writer that the work 

 here presented (itself somewhat crude and incomplete) may open 

 the way to more and better researches in this most interesting 

 field. 



