The Chemical Basis of 

 Heredity Determinants 



STEPHEN ZAMENHOF 



Students of the history of science cannot fail to notice how often 

 the issues most essential for our species are continuously avoided. 

 Thus, the science of heredity which affects us more than astronomy 

 was practically non-existent until the second half of the nineteenth 

 century although Mendel's conclusions (1866) were actually much 

 easier to arrive at and to accept than those of Copernicus (1530) or 

 of Harvey (1628). As late as 1872 Spencer writes: "We are obliged 

 to confess that Life in its essence cannot be conceived in physico- 

 chemical terms." 



By the end of the first half of this century the foundations for chemi- 

 cal explanation of several biological phenomena had already been laid. 

 However, the phenomenon of heredity was not attractive to the chemist, 

 perhaps because of a fear of the multitude of substances involved and 

 their insurmountable complexity; indeed, in contrast to simpler bio- 

 chemical functions, nothing less than the whole cell or at least the 

 chromosomal apparatus seemed indispensable as heredity determinant. 

 The remains of this Spencerian attitude still hamper modern research 

 on the chemistry of the transmission of heredity. 



Heredity Determinants 



Although the hypothetical "working gene" may be, indeed, a very 

 complex system, not all the elements of such a system need be essential 

 for the determination of heredity: a few may be actual heredity 

 determinants, and all the others merely auxiliary elements. This 

 essay deals with the search for the decisive factors. 



If one approaches the problem with an unbiased mind one also has 

 to test the possibility that the heredity determinants are not chemical 



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