1916] DEVRIES—DIMORPHIC MUTANTS 263 
specimen of O. Lamarckiana mut. semigigas described by Stomps,® 
-and a narrow leaved specimen, exactly resembling the type described 
and figured by GAGER? for a derivative of O. biennis. The speci- 
men of pallescens was discovered by chance, since almost none but 
mutants and a number of doubtful specimens had been planted 
out; it occurred among the latter and was distinguished as a new 
type only at the time of flowering. Thereupon, another part of 
the same sample of seeds was sown in 1911 and yielded two more 
specimens of pallescens, among about 250 flowering individuals. 
The self-fertilized seeds of these three mutants gave rise to a 
mixed progeny, the smaller half of which resembled the parent, 
whereas the remainder presented the type of O. Lamarckiana, 
duplicating this in all of its special marks and during all the stages 
of their development. In the following description I will, there- 
fore, indicate them simply as Lamarckiana, without discussing the 
question whether some internal characters might perhaps be differ- 
ent. But externally there is no difference; moreover, the progeny 
of this derivative Lamarckiana behaves exactly like that of normal 
ones. This splitting into these two types has repeated itself in 
the following generations and in all of the cases investigated 
Moreover, the pallescens seems to be mutable to a higher degree 
than O. Lamarckiana itself; for, although my cultures have been 
necessarily small, the number of mutants is very striking, reaching 
20 among about 500 specimens, or 4percent. From the first three 
mutants I have derived three pedigree families, which I will now 
briefly describe. 
PEDIGREE OF MUT. pallescens NO. 1 
IMO aoe Mutant Mutant 
IQII, 1913 ....Second generation 42 per cent pallescens Lamarckiana 1 mutant rubrinervis 
sg he ee Third generation 23-43 per cent em Lamarckiana Lamarckiana rubrinervis 
ie 
IONE 55. Fourth generation 24 per cent pallescens Lamarckiana Lamarckiana 
BOS ete aeec. Fifth generation 38 per cent pallescens Lamarckiana 
* Stomps, THEO. = ons Entstehung von Oenothera gigas DeVries. Ber. Deutsch. 
Bot. Gesells. 30:406. 
9GAGER, STUAR a iy Coe omeric inheritance in Onagra. Contrib. Brooklyn 
Bot. Gaiden: no. 3, Bull Torr. Bot. Club 38: 461-471. figs. 2. 1911. 
