THE CELLULAR BASIS 163 



differentiation and that neither is capable of 

 embryonic development in the absence of the 

 other. Differentiation is indeed the result of 

 the interaction of nucleus and cytoplasm, and 

 how then can it be said that the nucleus is the 

 only seat of the inheritance material? If held 

 rigidly, this theory involves the assumption 

 that the cytoplasm and all other parts of the 

 cell are the products of the chromosomes, and 

 that therefore the chromosome and not the cell 

 is the ultimate independent unit of structure 

 and function; an assumption which is con- 

 trary to fact. Furthermore, since heredity in- 

 cludes a series of fundamental vital processes 

 such as assimilation, growth, division and dif- 

 ferentiation, there is something primitive and 

 naive in the view that this most general pro- 

 cess can be localized in one specific part of the 

 cell, something which recalls the long-past 

 doctrine that the life was located in the heart 

 or in the blood, or the ancient attempts to find 

 the seat of the soul in the pineal gland or in the 

 ventricles of the brain. 



On the other hand it is objected by certain 

 investigators, notably by Child, Foot and Stro- 



