THE OCCURRENCE AND INHERITANCE OF SEX INTERGRADA- 
TION IN PLANTS 
Cecil Yampolsky 
In a previous paper (1919) I have called attention to sex intergradation in 
Mercurialis annua in both male and female cultures. It is my purpose here 
to discuss the general question of sex intergrades as they occur in the flower- 
ing plants. This discussion is based in a large measure upon the results 
reported in the paper mentioned above. 
There can be no question from the data at hand that sex in Mercurialis 
is a fluctuating rather than a fixed character expressing itself in a wide range 
of sex intergrades, including as the extremes some pure male and some pure 
female plants and midway between the extremes highly fertile monoecious 
forms. The sex intergrades here are all highly and equally fertile, and no 
suspicion of abnormality or of pathological conditions can attach to them. 
That there is a tendency to pure dioecism seems highly probable, but the 
transition from hermaphroditism is still represented by all possible grada- 
tions, showing most convincingly that theories of sex determination based 
on the segregation of fixed unit factors can have no significance for such 
types. 
Sex Intergrades 
Goldschmidt (1916a) reports in a preliminary paper upon the sex ratios 
in crosses between the European and Japanese races of the gypsy moth, 
Lymantria dispar. He obtains various gradations in the sexual condition 
unlike the well known gynandromorphs. His individuals do not, as in the 
case of the gynandromorphs, show a sectorial arrangement of the characters 
of the two sexes, but they do show different gradations between the ex- 
tremes of femaleness and maleness. His females show all the transition 
stages, such as feathered antennae, male wing pigmentation, the transi- 
tion of ovaries into testes, and the loss of the power to lay eggs. His males- 
show tendencies towards femaleness in a similar manner. For these in- 
dividuals he proposes the term intersexes. He finds that as his sex inter- 
grades approach the middle line between maleness and femaleness, they 
become more and more sterile, that is he obtains no fertile hermaphrodites 
such as occur for example in Mercurialis annua. In fact, although his 
forms show morphological intersexualism, they are functionally sexless in 
many instances. To be sure, he secures his intergrades by using as parents 
forms which in themselves possess functional sexual intergradation. As 
noted in my previous paper, there is a tendency in plant forms that exhibit 
gradations in sex (judged by the proportion of male, female, and hermaphro- 
