198 COOK 



MENDELISM AS A METHOD OF DESCENT. 



By means of these five categories, it is possible to describe 

 Mendelism, as well as other methods of descent, in a more 

 direct and definite manner. Thus Mendelism may be defined 

 as a method of descent which jnelds conjugates all like one 

 parent, and perjugates like both parents in the proportion of 

 three to one. But to clearly understand the status of Mendelism 

 as a method of descent it is necessary to compare it with other 

 methods, described in corresponding terms. To make formal 

 definitions and laws of Mendelism in the absence of any form- 

 ulation of other methods of descent, is to onl}' ^PPb' another 

 way of claiming unique significance for this one group of phe- 

 nomena, to the exclusion of others equally worthy of our atten- 

 tion. When the matter is thus brought to a definite issue it 

 becomes evident that there are numerous methods of descent 

 instead of one or two. Indeed, so many methods are now 

 known that a general classification or arrangement of them 

 becomes almost necessary. 



Such a classification of methods of descent seems likely to 

 afford a better means of comparison than by attempting to form- 

 ulate a series of new principles to correspond to the more abstract 

 presentations of Mendelism which have been made. Our so- 

 called natural laws and principles represent, after all, only 

 sequences, processes or groups of phenomena. To call any- 

 thing a law or a principle is to bespeak for it a somewhat super- 

 stitious reverence inconsistent with the thoroughly concrete 

 methods of treatment which afford the only assurance of per- 

 manent scientific results. Principles and laws are abstractions, 

 but processes are sequences of relations between tangible things. 

 Mendelism is one of these processes or methods of descent, but 

 it is not the only method, nor the most frequent or important 

 method. Nor does it differ in any very serious or important 

 respect from other methods of descent with which we are all 

 familiar. 



PRIMARY METHODS OF DESCENT. 



The tendency of the past has been to seize upon one or 

 another of the methods of descent as typical, and then to try 

 to prove that it includes or represents all the others. One way 



