2 MODES OF RESEARCH IN GENETICS 



methods of research. I shall try to point out, 

 with reference to an old problem, where it would 

 seem that current methods have encountered 

 definite limitations and wherein lies the special 

 value of each. If I can succeed in doing even so 

 much, something will have been gained, even 

 though it is not now possible to show any results 

 achieved by new points of view and new methods 

 in the field to be discussed. 



The problem to which attention is invited is 

 one of the most fundamental of biology, the 

 problem of heredity. In what is to follow I 

 shall try to do three things. 



First: to define the problem in strictly objec- 

 tive terms, free if possible from any implications 

 which have grown out of theories of the hereditary 

 process. 



Second: to examine critically the four chief 

 methods of investigation by which attempts have 

 been made to solve the problem, endeavoring to 

 show in how far each has failed to take us beyond 

 a certain point in our understanding of the matter. 



Third: to draw such conclusions from this 

 methodological critique in regard to the most 

 promising lines for future attack as seem war- 

 ranted by the results. 



I. THE PROBLEM OF HEREDITY 



The problem of heredity can be easily defined 

 in a general way in terms which are perfectly 



