608 SIDNEY I. KORNHAUSER 
Thus, as adults, the metabolism of the two sexes stands in con- 
trast: the female is continually storing food material in the for- 
mation of ova, the male is using up available material faster 
than it is being supplied by intake of food. With this difference 
in metabolism, it is clear that, while the adult female can supply 
the growing Aphelopus larvae which may happen to be present 
in her abdomen, the male is not so well equipped by nature. 
The male tissues must change their metabolic level if the host 
itself is to survive and if the parasites are to obtain sufficient 
food for their growth. This changed metabolism expresses 
itself in various ways. As was stated on page 546, parasitized 
adult males make their appearance in the field along with the 
females, a week or two later than normal males, indicating that 
their development has been retarded. They are less active 
than normal males, sitting immovable on the branches and feed- 
ing continuously. They become animals of high storage capac- 
ity, as is indicated by the increase in adipose tissue. The portion 
of the abdomen normally occupied by the testes is filled with a 
mass of greenish or yellowish fat, often containing remnants of 
testicular tissue. The parasites themselves are literally im- 
bedded in fat, and a comparison of histological cross-sections of 
abdomens of parasitized and normal males shows the great 
increase of adipose tissue in the former. I am greatly indebted 
to Dr. Oscar Riddle for a quantitative chemical analysis of the 
alecohol-soluble substances in normal and parasitized Thelia. 
Lots of ten individuals minus pronotum and head were preserved 
in alcohol for analysis. Two lots of parasitized males and one 
lot of normal males were analyzed. The parasitized males 
showed on the average an increase of 47 per cent of lipoids over 
the normal males. While the samples analyzed were too small 
and too few in number to be entirely satisfactory, yet they 
indicate the true state of affairs. 
Another change brought about by the parasites is seen in the 
production of melanin, which is reduced over the entire body of 
males with the exception of the punctures on the vitta. These 
are pigmented in parasitized, but not in normal males. This 
general reduction of melanin may be due to a decrease in the 
