OF ENVIRONMENT 133 



which mutation rests ensue previous to the reduc- 

 tion divisions leading to the formation of the 

 reproductive nuclei, some new methods of experi- 

 mentation were developed. Among other opera- 

 tions, solutions of sugar, calcium, potassiimi, and 

 zinc were injected by the use of hypodermic 

 syringes into the developing ovaries of Baiman- 

 niuj one of the evening primroses, early in 1905, 

 with the result that out of the several hundreds" 

 of seeds borne by the treated ovaries sixteen in- 

 dividuals were found to be notably atypic, among 

 other characters lacking the trichomes which are 

 so conspicuous with the parental form. These 

 reproduced themselves in the second and third 

 generations, coming true to the newly assumed 

 characters. 



The same method was tried with Oenothera 

 biennis (Plate II), the common evening prim- 

 rose of waste lands in eastern United States, with 

 the result that two individuals were found among 

 the seedUngs which were different from the par- 

 ents in a series of characters so distributed 

 through the ontogenetic period that the deriva- 

 tives ^ could be recognized by the first two leaves, 

 while the cotyledons were still waxing. This 

 form is now being cultivated at the Desert Lab- 

 oratory in the fifth generation, and is being 

 thrown against the climatic selective factors in 

 the mountain plantations at various altitudes. 



' The derivatives, lettered D in Plate II, are to be "compared 

 with the typical young plants, lettered T. 



