6 THE METHODS AND 



been part of the common stock of elementary 

 knowledge of all educated persons for about 

 half a century. The full consequences of this 

 double nature seem nevertheless to have 

 struck nobody before Mendel. Simple though 

 the fact is, I have noticed that to many it is 

 difficult to assimilate as a working idea. We 

 are accustomed to think of a man, a butterfly, 

 or an apple tree as each one thing. In order 

 to understand the significance of Mendelism 

 we must get thoroughly familiar with the fact 

 that they are each livo things, double through- 

 out every part of their composition. There 

 is perhaps no better exercise as a preparation 

 for genetic research than to examine the 

 people one meets in daily life and to try in a 

 rough way to analyse them into the two as- 

 semblages of characters which are united in 

 them. That we are assemblages or medleys 

 of our parental characteristics is obvious. 



