A CRITICAL EXAMINATION 23 



those fundamental statistical laws to which other 

 natural phenomena in general conform. 



The most important achievement of the Men- 

 delian method has been, I think, the demonstra- 

 tion that, on the one hand, hereditary differences 

 behave, in the main, as discrete units, which are 

 shuffled about and redistributed to individuals in 

 the course of the hereditary process, to a consider- 

 able degree independently of each other; and on 

 the other hand, that in typical cases this redistri- 

 bution follows the simplest of statistical laws of 

 dispersal, the point binomial. 



Mendelism finds its limitations, just as did the 

 biometric method, in the fact that from the logical 

 standpoint it is essentially a statistical method 

 which studies only the laws of distribution of 

 things given or assumed. It examines only the 

 distribution of hereditary specificities, and not at 

 all, directly, their origin or determination. The 

 former aim cannot be the goal of genetic science. 

 A method which can travel only so far cannot 

 hope to say the last word in the discussion of the 

 problem of heredity. As a mode of research the 

 Mendelian method of analyzing the progeny dis- 

 tributions rather than the ancestral will always 

 be used. It was indeed one of the most brilliant 

 methodological discoveries in the history of 

 science. But it has limitations in the direction 

 of what it can accomplish per se in elucidating the 

 problem of heredity. Already Mendelian workers 



