MUTATION 61 



cessful attempt to bring order out of chaos by classi- 

 fying the living world, and it served its purpose well 

 until Darwin's idea of half a century ago, that the 

 origin of all species is from preceding species, put an 

 entirely new face upon the whole matter. Organ- 

 isms of different species were found to be related to 

 one another, and even man could no longer escape 

 acknowledging his poor animal relations. As a 

 consequence, likenesses rather than differences there- 

 after claimed the most attention. 



During the reconstruction of phylogenetic trees, 

 which seized the imagination and became the prin- 

 cipal business of biologists as soon as the ** Origin of 

 Species " was made common property, the crotched 

 sticks in the woodpile of organisms, that had hitherto 

 been largely discarded, were most eagerly sought after. 

 It was just these scraggly sticks, that were neither 

 trunk nor limb-wood but combinations of both, 

 which told the story of continuity and were indis- 

 pensable in building up a reunited whole. 



As the analysis of the living world gradually came 

 to shift from species to individuals, it was shown 

 that individuals may be regarded simply as ag- 

 gregates of unit characters which may combine so 

 variously that it becomes more and more diffi- 

 cult to maintain constant barriers of any kind be- 

 tween the groups of individuals arbitrarily called 

 "species." 



The old species of the systematist, upon analysis 

 into their respective unit characters, dissolve into 

 numerous "elementary species" and "varieties" dif- 



