1918] DEVRIES—MASS MUTATIONS 381 
derived from the number of specimens at the time of planting out, 
minus the number of survivals. The results of the count on 
April 25, 1915, are given in table II. 
TABLE II 
OCHRACEA 
PARENT Tors 1 LOREA 
Living | Dead 
NOT: 340 162 89 | 88 I 
Sup Porn 360 202 93 63 2 
a er oes 120 74 29 16 I 
age eer 240 137 45 55 3 
ee ee 120 25 15 5 
OU co oes 1180 650 518 12 
Percentage. }. 2... «< 55 44 I 
The seedlings of the remaining five parents of 1914 were not 
counted in April, but at the time of flowering in August. Each of 
the groups yielded a large number of ochracea and one or more 
lorea, but the percentage for the first was now only 12. This 
figure is evidently due to the losses mentioned, since even during 
the summer usually many specimens of the type of ochracea are lost 
on account of their weakness. In 1916 I got about the same per- 
centage at the time of flowering, but did not estimate the losses 
during the spring. 
For this reason I repeated the sowing in the spring of 1917 with 
the preserved seeds of the same self-fertilized individual of 1915, 
taking every possible care to avoid the presumed losses. I planted 
out 7o seedlings, only one of which died; 20 were found in May to 
be ochracea, giving a total percentage of 30. This figure, therefore, 
should be substituted in table I for the 15 per cent given for the 
fourth generation. 
Moreover, in 1917 I sowed the seeds of four other self-fertilized 
individuals of 1915, taking the same precautions. The culture 
embraced 224 seedlings, of which 8 per cent were pale and weak and 
died soon after being transplanted, while 31 per cent were recog- 
nized in May.as ochracea. This gives a total of 39 per cent, which 
corresponds to the figures found in the best of the previous trials. 
