488 GENETICS IN RELATION TO AGRICULTURE 
the transplanted tissue failed to function. Accordingly as the matter 
stands at present with regard to the relation of soma and stirp it has not 
been demonstrated that any mechanism for the direct influence of the 
Fie. 193.—The offspring of the pair of albinos shown in Fig. 192. 4 and 5, young 
black females of the first litter; 6, young black male of the second litter; 7, 8, 9, skins of the 
black males found in utero after the death of No. 24. (After Castle and Phillips.) 
germ cells by the body exists; and such critical experimental evidence 
as has been obtained indicates that probably no such mechanism does 
exist. 
The Isolation of the Germ-plasm.—Many biologists see in the con- 
tinuity of the germ-plasm and in its apparent isolation from the soma an 
Digitized by Microsoft® 
