432 BOTANICAL GAZETTE [DECEMBER 
large number of zygotes to develop, for the number of ovules in all 
capsules appears to be about the same. Probably the zygotes 
which fail to develop into embryos represent the weaker individuals 
of mut. setacea, or perhaps some still more reduced mutation which 
is incapable of development. The problem, however, must be 
attacked by cytological methods. It is interesting to observe that 
the F;, with an average seed germination of 70 per cent, contained 
75 per cent of mutations. If all the seeds had germinated, and 
the additional plants had all been f. typica, there would still have 
been more than 50 per cent of mutations. It seems far more likely, 
however, that the seeds which did not germinate were either empty 
or else that they were the weak mut. sefacea. 
A comparable degree of mutability to that of Lexington E is 
known only in the case of O. Reynoldsii, in which mass mutation 
was first described. In O. Reynoldsii, also, the great increase in 
mutability is associated with an enormously increased degree of 
sterility. The data in regard to the latter species will soon be 
published elsewhere. 
A number of photographs were made to record the appearance 
of the mutations at various stages of growth. Figs. 1-5 show a 
portion of the F, progeny from F, parent Lexington E-5, recorded 
in table II. All of the characteristic mutations are shown, as well 
as several plants which became the parents of subsequent cultures. 
Fig. 6 shows 6 rosettes of mut. setacea, one of which will be found in 
fig. 3. Fig."7 shows two mature plants of the same mutation, of 
which one is shown in fig. 5. Fig. 8 shows 4 rosettes of mut. 
revoluta, 3 of which are likewise shown in figs. 4 and 5. A mature 
plant is shown in fig. 9. Fig. 10 shows 6 rosettes of mut. albicans, 
3 of which will be found in figs. 2, 3, and 4. Fig. 11 shows two 
cauline plants of the same form. The one on the left is just begin- 
ning to flower; the one on the right lingered in the rosette condition 
and would therefore have matured as a stronger plant than its 
sister. Rosettes of mut. formosa are shown in fig. 12. The main 
stem of the mature plant is shown in fig. 13, and the identical cross 
mut. formosaXf. typica in fig. 14. Fig. 15 shows young rosettes 
of f. typica and mut. gigas. The gigas plant was the particular 
individual in which E. G. ARzBERGER determined the chromosome 
