THE PURE LINE 119 



It is interesting to note that Johanssen himself, 

 who has been so prominently concerned in erecting 

 this barrier in the way of the evolutionary derivation 

 of species by natural selection, has recently reported 

 mutations arising within his pure lines of beans. 

 It must be admitted that to the skeptical there is a 

 vicious circle here, for when a variation fails to re- 

 appear in a subsequent generation, it may be ex- 

 plained as the failure of natural selection to act 

 within a pure line, but when a variation does reap- 

 pear it is hailed as a mutation ! 



In any event the way of experiment lies open, 

 and the evidence of investigators in this critical 

 field will be awaited with keen interest. 



