MIRACLES OF SCIENCE 



eould operate to produce new species. Thus the 

 transformation from, let us say, a tall to a dwarf 

 species of evening primrose, instead of requiring 

 centuries might take place in a single year. 



Although the evening primrose is the only plant 

 in which such marked mutations have been observed, 

 it is reasonable to suppose that other plants, and 

 animals as well, may show similar tendency to 

 marked variations under exceptional circumstances 

 (for example, through changed environment). So 

 the evolutionary process might go on with incom- 

 parably greater rapidity than had been supposed 

 possible without involving any force more mys- 

 terious than the accepted Darwinian principle of 

 "natural selection" and the survival of the fittest. 

 Thus any dispute about the adequacy of geological 

 time was shown to be unnecessary. 



THE PRODUCTION OF MUTANTS 



It must be observed that the sudden variations 

 which produced Professor de Vries' new species of 

 evening primrose may be spoken of as "spontaneous" 

 in the original Darwinian use of the word. No one 

 can explain, except in the most general terms, why 

 certain individual plants depart from their hereditary 

 type in so striking a manner. In general terms, how- 

 ever, it might be said that the mutation is doubtless 

 due to some changes of nutrition. In recent years 

 a large number of experimenters have been at work 

 endeavoring to ascertain what manner of influence 

 may be instrumental in causing such mutations as are 

 observed to occur. 



