THE BEHAVIOR OF UNIT CHARAC- 

 TERS IN HEREDITY 



BY 

 W. E. CASTLE 



No ONE recognizes more frankly and joyously 

 than would Darwin, were he here to-day, the 

 great advance which has been made in our knowl- 

 edge of heredity since his time. His work and 

 writings have pointed the way to that advance, 

 and it is largely owing to a return to the experi- 

 mental method of testing hypotheses, which Dar- 

 win used so successfully, that the remarkable 

 progress of the last decade has been made pos- 

 sible. We do, therefore, the greatest honor to 

 Darwin if we pause to consider what superstruc- 

 ture of knowledge has been built on the founda- 

 tions which he laid. This superstructure is, in- 

 deed, still in the building, and it is not easy in 

 aU cases to distinguish between the soHd structure 

 of proved fact and the scaffolding of hypothesis. 

 Still, the attempt should be made, and it will 

 give us encouragement to discover that, notwith- 

 standing the considerable amount of rubbish 

 lying about, there is, nevertheless, good con- 

 structive work going on here which gives prom- 

 ise of permanency. 



143 



