THE CELLULAR BASIS 181 



nucleus. Similarly, it may be argued, smaller 

 units of organization such as chromosomes or 

 chromomeres do not in themselves give rise to 

 any adult part, but only as they interact upon 

 other units are new parts formed. 



In many cases the first formation of such 

 new substances appears in the immediate 

 vicinity of the nucleus and, like assimilation 

 itself, is evidently brought about by the inter- 

 action of nucleus and cytoplasm. In certain 

 cases it can be seen that the achromatin and 

 oxychromatin which escape from the nucleus 

 during division take part in the formation of 

 new substances in the cell body, and since the 

 oxychromatin is derived from the chromo- 

 somes of the previous cell division, it is prob- 

 able that the chromosomes are a factor in this 

 process. 



Weismann maintained that the chromo- 

 somes and the inheritance units contained in 

 them undergo differentiation by a process of 

 disintegration and that these disintegrated 

 units escape into the cell body and there pro- 

 duce different kinds of cytoplasm in different 

 cells. A somewhat similar view was advanced 



