238 FINE-STRUCTURE OF PROTOPLASM II 



Moreover, Caspersson's measurements show that their appearance is 

 transitory and that they afterwards largely disappear. For this reason 

 Kiesel (1930, p. 185) stigmatizes as downright paradoxical the fact 

 that cytologists pay such conscientious attention to an unspecific 

 material like the desoxyribose nucleic acids, yet ignore the proteins, 

 with their specific structure, merely because constituents do not bind 

 the basic dyes used for staining cell nuclei. Posternak (1929) goes to 

 the length of relegating the nucleic acids to the rank of degradation 

 products of organic phosphorus compounds ; but this view is invalid- 

 ated by the morphological behaviour of the desoxyribose nucleic 

 acids during karyokinesis and the interesting fact that many co- 

 enzymes consist of nucleotides (co-dehydrogenase II and others, see 

 p. 208). 



I have therefore suggested the following hypothesis respecting the 

 function of the desoxyribose nucleic acids : The genes play no active 

 part during karyokinesis, but 2it& passive and in this state are distributed 

 by some process among the daughter nuclei. Their operative groups 

 must therefore be reactive in the active nucleus to fulfil their task, 

 but they must be screened off during nuclear division. This might be 

 effected by a loose binding of desoxyribose nucleic acid groups. It was 

 pointed out in the discussion of the phosphatides that, in the respira- 

 tory combustion of carbohydrates, those hydroxyl groups of the sugar 

 which are not subject to degradation are screened by phosphorylation 

 and are thus temporarily protected. Similarly, the phosphoric groups 

 of the nucleic acids might for the time screen the specific groups of 

 the genes during mitosis. This would account for the localization of 

 the desoxyribose nucleic acids in certain places only, viz., where the 

 genetically active groups are to be found in the fundamental protein 

 substance. They thus give a true picture of the distribution of genes 

 as proved by cytology. There is, then, nothing "paradoxical" about 

 the attempts to establish the distribution of the desoxyribose nucleic 

 acids in the chromonema down to the finest detail, since these are the 

 indicators, as it were, of the specific groups through which the genes 

 operate. 



The assumption that the desoxyribose nucleic acids accumulate only 

 in those parts which contain genes, and protect their active groups, 

 integrates the conflicting views championed by the theorists of he- 

 redity, one being founded on the structural chemical specificity of the 



