OENOTHERA RUBRINERVIS, A HALF MUTANT. 



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these sowings in 1916 from preserved seeds, giving them all the 

 care which the previous cultures and the first ones of 1916 had 

 shown to be necessaiy. Moreover, in 1913 I had self-fertilized a 

 third plant, besides the two mentioned in the table, and also sowed 

 its seeds. In this way I got in 1916 the following percentages for 

 the seeds of the three self-fertilized plants of 1913: 



Percentages of 0. deserens in cultures of 0. rubrinervis, strain B 



The result confirms the expectation and shows that the figures 

 given in the former table, although they give proof of the occurrence 

 of mass mutation among the offspring of every plant of rubrinervis, 

 are too low for the appreciation of the exact percentage of deserens. 

 This must be estimated at about 30 per cent, or almost one-third 

 of the whole progeny. In this race I self-fertilized three mutants 

 in 1913 and two specimens of deserens among their offspring in 1915. 

 I cultivated 150+84 + 180 specimens of the first group and left 

 about one-half of them to flower, and 70+89 plants of the second 

 group, all of which flowered in 1916. I had 573 plants in all, among 

 which 319 bore flowers and fruits. They were all uniformly deserens, 

 showing the marks of the type as previously described. No speci- 

 mens of rubrinervis and no new mutants were observed among 

 them. For one mutant of 1913 and for two plants of the second 

 generation in 1915 I determined the amount of germs in the seeds 

 and found 97—96 and 98 per cent, or an almost total absence of 

 empty grains. 



Besides the two described families of 0. rubrinervis I have con- 

 trolled the seeds of some mutants in order to know whether all of 

 them contained specimens of 0. deserens and in percentages point- 

 ing to mass mutation. I found the following figures: 



Percentage or deserens among the offspring of 

 Mutants 



