370 



OENOTHERA RUBRINERVIS, A HALF MUTANT. 



and so I studied in 1916 the progeny of three specimens of lucida 

 from previous crosses. 



Splitting progeny of 0. hybr. lucida; cultures of 1916 



Moreover, in 1916 I self-fertilized some specimens of lucida taken 

 in the first generations of the crosses mentioned, sowed their seeds 

 in 1917, cultivated all the seedlings until the time of ripening their 

 first fruits, and counted them repeatedly during the summer. The 

 difference between the deserens and the lucida was very striking, 

 the first reaching only half the height of the lattei. I have broken 

 the stems of all the plants in August, at the time of the last counting, 

 and found all the deserens brittle and all the tall ones tough. The 

 first were evidently deserens and not rubrinervis, as seen by the 

 characters described for these two types. Among the tall ones, 

 however, I have not succeeded in finding any difference, the type 

 of lucida prevailing to the apparent exclusion of that of 0. Lamarcki- 

 ana. For each of the crosses mentioned in the following table I had 

 58—60 flowering specimens in August. 



Splitting progeny of hybrid lucida; culture of 1917 



Oenothera Lamarckiana mut. oblonga and mut. nanella 



Our conception of Oenothera rubrinervis as a half mutant may 

 be applied to 0. oblonga, and explain its behavior in crosses in an 



