1915] BARTLETT—MUTATION IN OENOTHERA IOI 
Some of the progeny of two of the parents from which F, plants 
were obtained (Lexington C-17 and Lexington C-21) are shown in 
figs. 9-11. In fig. 9, no. 3 is a young specimen of mut. fortuosa, 
as yet only vaguely suggesting the characters: which give this 
mutation its name. The other 5 plants are typical.mut. num- 
mularia, comparable in state of development with nos.:1 and 2 in 
fig. 3, and nos. 10 and 11 in figs. 5 and 6. Fig. ro-shows three of 
the types which are included in the F, cultures from mut. num- 
mularia. Nos. 8 and 15 are characteristic plants of mut. tortuosa; 
nos. 13 and 16 are mut. rubricentra; nos. 35 and 36 are typical mut. 
nummularia. In order to show the striking uniformity of the 
nummularia plants 6 more of them are shown in fig. 11. 
The frequency of mut. nummularia 
In order to determine the frequency with which O. pratincola 
gives rise to mut. nummularia, large cultures were grown in the 
greenhouse during the winter of 1913-14. As usual, the seeds 
were sown on sterilized soil and transplanted to seed pans as soon 
after germination as circumstances permitted.2 Remaining wild 
seeds of the original collections gave additional F, cultures of 
Lexington C, A, B, and E. F, cultures were also grown from the 
wild seeds of Lexington F, G, H, and I, which had not been previ- 
ously planted. It will be remembered that mutations had been 
detected during the first year of cultivation only in Lexington C, 
and in this strain only because of the accidental application of 
the method of selective germination. The other strains were found 
to be quite as mutable as Lexington C when all of the seedlings 
were retained until old enough to show their distinctive character- 
istics. In addition to the F; cultures, F, cultures were grown from 
seeds of 8 self-pollinated F, sister plants of Lexington C, 1 self- 
pollinated plant of Lexington A, and 2 self-pollinated plants of 
Lexington B. These F, progenies from guarded seeds were found 
to contain approximately the same proportion of mutations as 
the F, progenies from unguarded wild seeds. 
* The writer wishes to express here his appreciation of Mr. Martin BiLon’s 
painstaking and efficient care of the germination pans and the young seedlings. 
