Spirazines 35 



as illustrated in Figs. 4a and 5a. The formation 

 of substances like arginine and uric acid may thus 

 be accounted for in several different ways as 

 shown in the accompanying diagrams. 



In the nucleated cells of plants and animals 

 these urea and guanidine complexes occur princi- 

 pally in the chromatin material of the chromo- 

 somes. This chromatin material has a strong 

 affinity for dyes so that it stands out very promi- 

 nently in stained preparations, but the fact that 

 it is conspicuous in appearance does not prove 

 that it plays an important part in vital processes. 

 If purine derivatives are formed in the manner 

 suggested in the preceding diagrams, then it 

 appears that the chromatin material of the 

 nucleus, which has generally been regarded as the 

 seat of heredity, is actually nothing more than an 

 accumulation of waste material. 



It is a significant fact that after cell division is 

 complete, the chromatin material spreads out 

 into irregular patches over ths surface of the 

 nucleus and is probably absorbed by the cyto- 

 plasm while a new set of chromosomes develops 

 in the interior of the nucleus. In order to ex- 

 plain the supposed genetic continuity of this 

 chromatin material it has usually been assumed, 

 although not supported by a trace of experi- 

 mental evidence, that at least a portion of it is 



