1916] DEV RIES—DIMORPHIC MUTANTS 27% 
cm. ‘The spikes were densely flowered, the flowers a little smaller, 
the fruits thin and long. The production of pollen was insufficient 
in many flowers, but this may have been the effect of the ‘ndi- 
viduals being transplanted from their boxes to the bed in June, 
which is relatively late in the season. The seed developed badly 
and contained only a small percentage of normal grains. 
I have sown the seeds of 8 of the 9 specimens with the parental 
type, and of two of the type of O. biennis Chicago. The first split 
into two types, the second only repeated the form of the parent. 
The splitting percentages were 11, 12, 13, 15, 15, 17, 18, and 25, 
with a mean of 16 per cent, but the germination had been very 
poor, giving only 444 seedlings for the 8 boxes. The progeny of 
the two specimens of the Chicago type was uniform with 252 and 
60 seedlings. I counted them in May and June, and left one group 
of each type to flower. The group from the saligna type contained 
two flowering saligna, identical with those of the second generation; 
that of the atavists 60 flowering plants of the uniform type of 
O. biennis Chicago. From these facts we may conclude that in 
this rdce all of the specimens of the parental type give a dimorphic 
progeny, while the offspring of the plants with an atavistic type 
' Temains uniformly so. Resuming the cultures, we get the follow- 
ing pedigree: 
MOIS oe Mutant Mutant 
Work. Second generation —_50 per cent saligna ome 
IGS Third generation 16 per cent saligna Chicago Chicago 
The behavior is exactly the same as in the dimorphic races 
issued from O. Lamarckiana. 
Crosses of Oenothera Lamarckiana mut. cana.—As indicated 
on p. 258 I chose in 1913 the second generation of a cana mutant 
which arose from O. lata (no. 3) for a series of crosses. This cul- 
ture was the most vigorous one of all my annual cana families, and 
its percentage figures seemed to be more normal than in the other 
cases. The crosses were made in both directions with the pure 
strains of my species and races described in Gruppenweise Art- 
bildung, and the seeds were sown in 1914. This first generation 
