18 
SIDNEY I. KORNHAUSER 
that the genes for the male secondary sexual characteristics 
fail to find the necessary conditions for their expression in the 
developing soma. 
7 . GYNANDROMORPHS AND MOSAICS 
In insects and Crustacea there occasionally appear abnormal 
individuals which are mixtures of male and female individuals. 
Sometimes the demarcation is exactly median, one half being 
male, and the other half female. These are true gynandromorphs. 
There are, however, cases where the division is dorso-ventral or 
anterio-posterior, and again the individual may be a ^ ^patch-quilt’^ 
of male and female parts, these latter being mosaics or intersex 
individuals such as described for moths by Goldschmidt and for 
daphnids by Banta. 
Insect gynandromorphs do not necessarily have the gonad of the 
corresponding sex in their respective halves, showing that the 
soma is not moulded by sex hormones. The cause of gynan- 
dromorphism was studied by Boveri and also by Morgan. Bo- 
veri claimed for gynandromorph bees of crossed races that the 
male half was maternal, and the female half hybrid. If after 
the division of the egg nucleus a sperm united with one of the 
two daughter nuclei, that half would be female, whereas the 
sister nucleus developing parthenogenetically would form a 
male half which would be purely maternal. This explana- 
tion holds good for some cases, but Morgan finds in Drosophila 
that the male portions often bear paternal characteristics due 
to genes lying in chromosomes other than the X-chromosome. 
He, therefore, concludes .that at times an X-chromosome is lost 
in the mitosis of a (female) zygote, and the nucleus which fails 
to get two X-chromosomes develops into the male portion of the 
gynandromorph. A misplaced X-chromosome in a primary 
germ cell may cause testes to form in a female. Such a case was 
found in Thelia where an actual chromosome count proved an 
X-chromosome to be missing in all the countable metaphase 
plates. The soma of the individual was purely female, however. 
It is rather difficult to offer any simple mechanical explanation 
for the mosaics or sex intergrades of moths and daphnids. Gold- 
