130 SEX INHERITANCE 
appeared. The results are in many respects like 
those of Goldschmidt. 
Sturtevant has studied a race of intersexes in 
Drosophila simulans. The intersexual individuals 
are all alike, and have parts that are characteristic 
of normal individuals of both sexes (ovipositor, 
seminal receptacle, etc., of female; genital segment, 
claspers, anal plates, etc., of male). Genetic evi- 
dence shows that the intersexes are females, in 
that they have two X-chromosomes, even in the 
male-appearing parts. The result is produced by 
a second-chromosome recessive mutant gene. In 
this case, then, we are dealing with a modification 
of the development of the female,—not with a 
disturbance in the usual sex-determining mechanism. 
In the cases of intersexuality recorded by Gold- 
schmidt, Harrison, and others there seems to be no 
proof that there is a single sex-determining gene that 
has a different ‘‘ potency” in different species. The 
case of Drosophila simulans shows that it is not admis- 
sible to assume such an explanation without proof. 
TRIPLOID INTERSEXES IN DROSOPHILA 
MELANOGASTER 
In Drosophila melanogaster, Bridges has found a 
strain that continually produces individuals that 
are intermediates between males and females. These 
““intersexes”” can always be easily distinguished 
from normal males or females because of their 
larger size, their coarse-textured eyes, and by other 
