410 Experimental Zoology 
view, they will be maternal. At present we lack the data to 
decide between these alternatives. 
In other groups of animals, gynandromorphous forms are 
great rarities. Weber described a finch that had feathers like 
the female on the left side and like the male on the right. There 
was also an ovary on the left side and a testis on the right. Un- 
til we know more of the conditions that determine the sex of 
birds, it is useless to speculate about this case. 
The Sex of Multiple Embryos 
Another group of facts discovered in other hymenoptera seems 
to show that the sex of the embryo is already determined in the 
egg. The chalcid fly (Ageniaspis fuscicollis) lays its eggs in the 
egg of amoth. Both eggs develop, the latter into a caterpillar 
and the former into its parasite. The parasite develops in a 
most remarkable manner. Marchal (1904) found that from a 
single egg a chain of embryos develops, and these embryos are 
all of one sex. Bugnion had already (1891) observed that the 
individuals that emerge from a single caterpillar are generally of 
one sex, and both authors have interpreted the result to mean that 
if the egg has been fertilized, a chain of female individuals is 
formed ; butif the egg is not fertilized, males are produced. More 
recently Silvestri has studied the early development of another 
insect (Litomastix truncatellus), and finds, in fact, evidence 
showing that the eggs may or may not be fertilized, and that it con- 
tinues to develop in either case. Silvestri finds that a single egg 
may produce a thousand sexual individuals, and also several hun- 
dred sexless larve that lack the circulatory and respiratory system. 
The details of the early development of these forms are remark- 
able, but cannot be considered at present. The point of espe- 
cial importance is the conclusion that the sex of the embryo 
must be determined at an early stage, and is not later altered, 
since all the sexual embryos of a chain are of the same sex. 
It is true that there may sometimes emerge from a caterpillar 
both males and females, but this is supposed to be due to two eggs 
—one fertilized, the other not —having been laid in the same egg 
