THE CELL 59 



nucleus e nucleo and even a fourth, postulated 

 by Boveri in 1903, Omne chromosoma e chro- 

 mosomate, for we know that as living thing 

 comes from living thing and cell from cell and 

 not otherwise so nucleus is derived from nucleus 

 and chromosome from chromosome and also 

 not otherwise. 



But though the nucleus is the essential part Relations 

 of the cell and its chromosomes are the most and 1 cell 1 " 

 essential factor of the whole structure it does 

 not follow nor is it the case that the nucleus 

 or its chromosomes are self-sufficing. This has 

 been proved by direct experiment. It is pos- 

 sible for the skilled manipulator to deprive a 

 unicellular organism of its nucleus. What 

 happens? The cell thus emptied of its most 

 important part does not immediately die. 

 For a time it will go on exhibiting what we 

 shall shortly learn is one of the most important 

 and characteristic activities of life, namely 

 irritability. But it has lost, and that per- 

 manently, all its former powers of assimilation, 

 of growth and of repair. It is not dead but it 

 is dying and nothing can hinder or delay its 

 final death. Hence, as Roux and others claim, 

 and it seems justly claim, the nucleus is the 

 controlling agency in the cell. 



But, on the other hand, if the cell cannot 

 g;t on without the nucleus, neither can the 



