Igto] SHULLIL—INHERITANCE OF SEX IN LYCHNIS 117 
Lychnis, the difference between Bryonia and Lychnis is reduced to a 
question of dominance of the hermaphrodite (or modified male) 
condition. In order that Bryonia alba should breed true, the monoe- 
cious (or modified male) character must be homozygous. The fact 
that in Bryonia a cross between the female B. dioica and the monoe- 
cious B. alba produces only females, indicates that the monoecious 
character is capable of coming to full expression only when present 
in the homozygous state. In other words, while the monoecists are 
modified positive male homozygotes, absence of this modified male 
character is almost perfectly dominant over its presence, so that the 
heterozygous individuals which constitute the F, of this cross almost 
or quite completely lack the male character. In this connection the 
occurrence of occasional male flowers on a few of these females of 
the F, may be of interest as showing a slight influence of the ee 
gene for the modified male or monoecious sex. 
In Lychnis, on the other hand, the presence of the hermaphrodite 
character is dominant over its absence, as demonstrated by the fact 
that the hermaphrodite mutants are heterozygous with respect to 
sex. In the following table a comparison may be made between the 
two methods of explaining the character of the F, hybrid generation: 
TABLE III 
ASSUMPTION: The female is a positive homozygote 
BRYONIA LycHNIs 
Cross Assumed : 
ed Resultant Somatic 
char paces ter of jue pore a composition of type of 
parental gametes offspring offspri gametes offspring offspring 
gx Sox 2 92 and¢ gands | 92°X9 9¢and ¢ gand 4 
ex BEX 32 andy Qand 4 oo | 9gand¢ gand ¢ 
Xs 92X98 O38 2 gexXe~ | Qvandy gand % 
3X SOX 88 fe} i] 9oxXeY | andy gand ¥ 
ASSUMPTION: The female is a negative homozygote 
gxXs * 294 ae and ¢ sands | 9929s | ¢2@and99s | Gandé 
ox<s 2293 294 and ae gandé | 92x9es | @2@and¢es | Sands 
exe 82 K99Ry 2 99998 | 92andeey | Gandy 
Xe POSE X 2989 See % ge oey | 99and 99% and 3 
No decision can be made between the two methods of explanation 
contrasted in this table until the F, has shown the dependence or 
