438 BOTANICAL GAZETTE [December 



(This plant is shown in figs. 5 and 14.) All three mutations are 

 discussed here, but full data and illustrations are reserved for a 

 paper entitled "Certain mutations and hybrids of Oenothera 

 pratincola," to appear later in this journal. 



Mut. angustifolia. — It has been found that mut. angustifolia 

 from ordinary strains gives no descendants resembling itself; aside 

 from the usual small proportion of other mutational tjrpes, the 

 progeny consisting of f. typica only. The variation, although 

 striking and entirely discontinuous, appears to be somatic. In this 

 connection it is interesting to note that a perfect branch of f . typica 

 has been observed as a bud sport on mut. angustifolia. As would 

 be expected, mut. angustifolia crossed reciprocally with f. typica 

 gives f. typica together with the usual few mutations. The 

 hereditary behavior may be stated: 



mut. angustifoliaXxant. angustifolia -> f. typica 

 mut. angustifoliaXi. typical' f. typica 

 f. typicaX^oiut. angustifolia-^ f. typica 



The behavior of mut. angustifolia from Lexington E is most 

 remarkable. The parent plant was a sister of the typica plant whose 

 progeny is analyzed in table III, but the degree of mutability proved 

 to be much more extreme than in the case of the typica sister. 

 Only two plants in the progeny, out of a total of 505, were f. typica; 

 the other 503 plants, 99 . 6 per cent of the progeny, were mutations 

 belonging to the group characteristic of Lexington E. The results 

 are summarized in table IV. 



The cross mut. angustifoliaXi- typica and the reciprocal gave 

 respectively 100 per cent and 91 . 5 per cent of mutations. By com- 

 parison with table III it will be seen that each of the reciprocal 

 crosses tends to show the same degree of mutability as the female 

 parent. To be sure, there would seem to be a considerable dis- 

 crepancy between 74.3 per cent, representing the mutability of 

 f. typica, and 91.5 per cent, representing the mutabiUty of f . typica 

 Xmut. angustifolia. No significance can be urged for this dis- 

 crepancy, however, when we consider that one of the cultures from 

 a single capsule of f . typica contained 92.2 per cent of mutations 

 among 102 plants, as compared with 91.5 per cent of mutations 



