40 MODES OF RESEARCH IN GENETICS 



nomenon of heredity. The distribution of heredi- 

 tary specificities, their putative morphological 

 "bearers," and many other things about them 

 have been studied more or less exhaustively. The 

 things themselves have been speculated about, but 

 not investigated to any but the slightest extent. 



It is, however, plain, I think, what must be 

 the mode of attack on this outstanding problem of 

 genetics. In the present state of knowledge it is 

 beyond dispute that the basis of the specificity 

 of living substances lies in its chemistry. This 

 plain fact has long been recognized by biologists, 

 but until very recently this recognition has been 

 equivalent practically to an Ignorahimus. The 

 obvious complexity of the chemical processes 

 going on in living material has made any direct 

 investigation of the problem from this side seem 

 hopeless to the biologist. But this period of 

 despairing wonderment is passing, and that 

 rapidly. The remarkable development of bio- 

 chemistry in the last twenty years has put at the 

 disposal of the geneticist a new technical equip- 

 ment with which he may directly attack problems 

 which formerly seemed impossible of approach. 

 To mention but a single instance by way of illus- 

 tration, the science of serology, which has so far 

 been developed almost exclusively as an adjunct to 

 medicine, puts into the hands of the biologist a 

 technique of enormous possibilities in solving the 

 most fundamental problem of genetics. 



