iQiS] BARTLETT— MUTATION IN OENOTHERA lOI 



Some of the progeny of two of the parents from which Fi plants 

 were obtained (Lexington C-17 and Lexington C-21) are shown in 

 figs. 9-1 1. In fig. 9, no. 3 is a young specimen of mut. ioriuosa, 

 as yet only vaguely suggesting the characters which, give this 

 mutation its name. The other 5 plants are t5rpical mut. num- 

 mularia, comparable in state of development with nos. i and 2 in 

 fig. 3, and nos. 10 and 11 in figs. 5 and 6. Fig. 10 shows three of 

 the types which are included in the Fj 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 0. 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." Remaining wild 

 seeds of the original collections gave additional Fi cultures of 

 Lexington C, A, B, and E. Fi 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 Fi cultures, F2 cultures were grown from 

 seeds of 8 self-pollinated Fi sister plants of Lexington C, i self- 

 pollinated plant of Lexington A, and 2 self-polHnated plants of 

 Lexington B. These F2 progenies from guarded seeds were found 

 to contain approximately the same proportion of mutations as 

 the Fi 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. 



