72 



Plant-Breeding 



At this stage of the experiment, de Vries became expert 

 in detecting variations at an early period. This accounts 

 in part for the large number of mutants found in the 

 fourth generation. By being able to pick out the mutat- 

 ing forms at an early age, a much larger number of the 

 diverging types could be obtained in proportion to the 

 total number of individuals. 



De Vries gives the following table which represents 

 graphically the results from eight generations of a mutating 

 strain of (E. Lamarkiana : 



MUTATING STRAINS OF (E. LAMARKIANA 



De Vries' laws of mutability of the evening-primroses. 

 de Vries deduced certain laws from the mutations in these 

 (Enotheras. " Obviously," he says, "they apply not only 

 to our evening-primroses, but may be expected to be of 

 general validity." 



These laws are as follows : 



1. New elementary species appear suddenly, without 

 intermediate steps. 



