NUCLEUS AND CYTOPLASM IN HEREDITY 1 



PROFESSOR MICHAEL F. GUYER 



That there is a physico-chemical basis of heredity and 

 that it is, if not exclusively, at least fundamentally bound 

 up in the proteins of the germ-cells, we know for certain. 

 If there is anything else than this physico-chemical basis 

 we do not know it. But even should there be, it is incon 

 ceivable that it is not subject to physico-chemical agen- 

 cies and limitations, and we are bound, therefore, to con- 

 tinue our search for these material factors as long as we 

 can unearth new facts or arrive at new generalizations. 



Before undertaking a discussion of the germ-cell, how- 

 ever, I wish to call attention to certain chemical facts 

 that are frequently overlooked or slighted by the biologist. 



In chemical reactions we have not only to take into 

 account the initial chemical substances and such external 

 factors as pressure, temperature, etc., but in many in- 

 stances we must reckon also with the quantitative rela- 

 tions, especially the concentrations of the various sub- 

 stances, and the velocities of their reactions, since altera- 

 tions in either of these factors may profoundly modify 

 the end-products of the reactions. A very simple ex- 

 ample of quantitative relations is seen in the combination 

 of carbon and oxygen. If much oxygen is present, C0 2 

 is formed, if little CO, and these are two very different 

 substances, particularly when physiologically considered. 

 Or, when chlorine acts upon methane, ('If,, depending 

 upon purely quantitative relations and physical condi- 

 tions, any one of four different substitution products 

 ranging from CII^Cl to CC1 4 may be secured. 



The questions of quantitative proportions and of veloci- 

 ties are of especially great significance in a sequence of 



1 Read before the American Society of Naturalists, at Ithaca, December 

 30, 1910. 



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