536 
STRUCTURE AND LIFE HISTORIES 
tion. The great contribution of de Vries is that he demon- 
strated that evolution may be studied by the method of 
experimentation. The next step for him to take after 
discovering the two forms that he supposed to be mutants, 
was to breed them in carefully guarded, pedigreed cultures 
FIG. 402. Giant evening-primrose (Enothera gigas, a mutant from 
(Enothera Lamarcklana, originated in 1895. (Cf. Fig. 401.) (After de 
Vries.) 
in his garden, and also to breed the parent form, (Enothera 
Lamarckiana, and see if he could observe the two forms 
above mentioned, or other mutants, arise from seed pro- 
duced without crossing with any other species. 
The entire story of this classical series of experiments 
is too long to be told here. Suffice it to say that de Vries 
did observe numerous other aberrant forms arise, and also 
