544. SIDNEY I. KORNHAUSER 
in this assumption since they found no correlation between the 
length of the forceps and the number of gregarines in adult 
insects. It might here be interjected that, since the adult struc- 
tures of insects cannot be altered, it would be necessary to 
know how many gregarines had been present in the alimentary 
tract previous to the final molt, at which time their presence 
might influence the imaginal structure. 
3. MATERIAL AND METHODS 
A brief description of the life history and habits of Thelia and 
its parasite Aphelopus will be given in parts 4 and 5. The 
principal collecting ground was situated about two and a half 
miles from the laboratory, and material was procured practi- 
cally every second day and brought in alive. For further obser- 
vations on living specimens, the insects were placed in cages on 
cut locust branches or put upon branches of locust trees growing 
near by, and enclosed in bags of cheese-cloth or mosquito net- 
ting. The branches in the cages must have the cut ends in 
water and the leaf surface reduced to remain fresh. They must 
be renewed every second or third day to keep the animals in 
good condition so that they will grow and molt. 
For a study of the parasitized adults and normal individuals, 
first the pronotum with head and prothorax attached was re- 
moved, pinned, numbered, and shielded from the light to pro- 
tect the colors, which fortunately keep well in dried specimens. 
The body was placed immediately in a dish of physiological salt 
solution or in Ringer-Locke solution, and dissected under a 
binocular microscope. The abdomens were cut open dorsally 
with a fine microscissors so as not to injure the genitalia. A 
careful search was then made for any remnants of gonads in 
parasitized individuals. The light from a Nernst glower directed 
upon the interior of the animal by a condensing flask added 
greatly in discovering any minute gonads which might be pres- 
ent. The gonads discovered were removed and fixed for section- 
ing: testes in Bouin’s fluid, ovaries in Gilson’s fluid. The body 
and parasites were separately preserved for further study, usu- 
ally being put into 80 per cent alcohol. Body, pronotum, and 
