Modification of Germinal Constitution of Organisms 1 53 



which the father came. He himself was born in a litter which con- 

 tained spotted young, whereas neither the pure-bred black race that 

 furnished the graft, nor the albino race that received it was character- 

 ized by spotting. 



Inasmuch as the offspring of albino parents are in\'ariably albinos, 

 it is certain that the six pigmented offspring of the grafted female were 

 all derived from ova furnished by the introduced ovarian tissue taken 

 from a black guinea-pig. This tissue was introduced while the con- 

 tained ova were still immature, and it persisted in its new environ- 

 ment for nearly a year before the eggs were liberated which produced 

 the last litter of three young. These young, like the earlier litters, 

 gave no indication of foster-mother influence in their coloration. 



The conclusion is forced upon us that the egg cell during its growth 

 does not change in germinal constitution. Its growth is like the 

 growth of a parasite or of a wholly independent organism; what it 

 takes up serves as food; this is not incorporated merely in the growing 

 organism; it is made over into the same kind of living substance as 

 composes the assimilating organism. 



In all of these transplanted germ glands, it is true, as 

 Castle recognizes, that his evidence and that of others does 

 not disprove the possibility of foster-soma influence, but it 

 is certain that the evidence is at present entirely against 

 such influence. There are, however, two possibilities present 

 in these experiments which should be kept clearly in view: 



1. The transmission of some character from the foster 

 soma to the germ and its incorporation therein. 



2 . The power of the foster soma to produce new surround- 

 ings as a result of the transplantation, thereby arousing 

 new physical or chemical activities incident upon the trans- 

 planted germ cells. 



If the first efTect occurs as a result of the transplantation, 

 it is to be expected and must be proven that some essentially 

 entire characters are introduced from the foster soma into 

 the alien germ cell and this seems in all critical experiments 



