SEXUAL CHARACTERISTICS OF THELIA 543 
88), Potts (06), and Smith (10) show conclusively that in- 
fected males develop the secondary sexual characteristics of the 
female. The abdomen assumes the general form characteristic 
of the female, even bearing biramous abdominal appendages. 
The large chela of the male is replaced by the slender claw of 
the female. Smith (11, ‘13) and Robson (11) have studied the 
effect of the parasite on the lipochromes, fats, and glycogen 
content of Carcinus and Inachus. In parasitized Carcinus males 
the yellow lipochrome characteristic of the female blood ap- 
peared. The fat content of the blood and liver increased, whereas 
the glycogen content decreased. These changes show that 
the metabolism of the parasitized animals had become female. 
Smith believed that the roots of the parasites made a demand 
upon the soma of the host similar to the demand for fat made by 
an ovary. The response to this demand, the assumption of 
female metabolism, carried with it the production of female 
secondary sexual characters in the morphology of the host. 
Altered metabolism brought about changes in the blood of the 
male which stimulated the development of the latent female 
characteristics. It is not the absence of the testes, but the 
presence of the parasite acting like an ovary which brings about 
the changes in the males. 
Not only rhizocephalans, but also protozoa may alter sexual 
characteristics. Thus Smith (’05) described changes in the crab 
Inachus due to a gregarine. The abdomen and claw of the 
male were altered much as described above for the barnacles. 
Only those individuals in which sporozoites were liberated in 
the haemolymph showed modifications. No case exactly parallel 
to this is known in insects. Grassi and Sandias (’93) maintained 
that the presence of Protozoa in the intestinal caecum prevents 
the full development of both internal and external genitalia in 
termite workers. When the Protozoa are killed or removed by 
feeding saliva, the purged individuals become sexually mature 
substitute kings and queens. Wheeler (’10) was inclined to 
believe that the dimorphism in the males of Forficula, based on 
length of the forceps, might be due to the gregarines infesting 
their alimentary tracts. Brindley and Potts (’10) do not believe 
