No. 533] NUCLEUS AND CYTOPLASM IN HEREDITY 



287 



catalysis, therefore, we have at the same time doubtless 



We know that different ferments act differently on the 

 same substance and that the same ferments may act on 

 different substances within certain limits. To realize the 

 truth of the first proposition we have only to compare the 

 results of the butyric, the lactic and the alcoholic fer- 

 mentations of grape sugar. As to examples of the same 

 ferment acting on different substances, we may point to 

 the fact that some varieties of yeast will act readily on 

 '/-fructose, r/-glucoso, and r/mannose. They will not act 

 on '/-galactose, however. Furthermore, none of the other 

 known aldose hexoses and ketose hexoses are acted upon 

 by yeasts. In the case of yeast, then, where a given 

 enzyme acts on more than one substance, the molecular 

 configuration of the respective substances must be closely 

 similar. This seems to be a general rule. We do not 

 find the proteolvtic enzvme trypsin attacking anything 

 but proteids, although it operates on different kinds of 

 proteids. Even oxidizing ferments are not exceptions 

 in this respect, for certain of them will yield oxidations 

 in some compounds and not in others that are readily 

 oxidizable under the influence of a different oxidizing 

 ferment. 



But granted that in living protoplasm ferments play the 

 important role of velocity regulators and consequently of 



where should we look for then in the germ-cellf It is 

 now a matter of common knowledge that probably many 

 ferments are closely associated with nuclear activity and 

 presumably originate within the nucleus. The present 

 tendency is to regard the dissolution of the nuclear mem- 

 brane from time to time as a means of distributing sub- 

 -b-niees to the cytoplasm. Particularly in the case of the 

 germinal vesicle of the egg, upon dissolution of the mem- 

 hrail «'. there is a copious discharge of nuclear material 

 into the cytoplasm, and one would naturally infer that 

 this is in some way a preparation for the subsequent rapid 

 differentiation which will occur. 



