14 Annals Entomological Society of America _[Vol. VII, 
reaching beyond the point of union of the mid and fore-intestine 
in the region of the thorax, and are held in place by the fat 
tissue. Ina longitudinal section they appear as in Fig. 47 Pl. VI 
The individual cells consist of a homogeneous cytoplasm in 
which vacuoles are found in the outer portion and also near the 
nucleus. Secretions are sometimes seen in these. The nucleus 
is irregular, and often greatly branched, sending long arms into 
the cytoplasm. It is densely packed with chromatin granules. 
The larva were mostly fixed in Dietrich’s fluid, and stained 
with borax carmine and Lyons blue. This proved very satis- 
factory for general work, but the best results were obtained 
when the larve were fixed in hot Gilson’s fluid. 
The cells are very active in secreting a colorless fluid duding 
the period of gall-formation, which continues from the end of 
June until the middle of August. At this latter time, the larva 
has reached the fourth stage, measuring 134mm. There is 
somewhat of an increase in the size of the cells up to this point, 
which may be in proportion to the demand upon them. After 
this there is a slight decrease to a constant size, which is retained 
until degeneration begins. The following table shows the 
increase. 
TABLE II. 
LENGTH SIZE OF CELLS 
Larva 500u 64u.x72u. molt. 
£ 750u. 64u.x80u. molt. 
e lmm. 72u.x80u. 
144mm. 72u.x82u. molt. 
. 14mm. 72u.x88u. Z 
« 134mm. 112u.x120u. molt. 
o 2mm. 72u.x96u. 
ae 214mm. 72u.x88u. molt. 
246mm. 72u.x88yu. 
As pointed out earlier in this paper, molts occur at 500u, 
750n, 144mm., 134mm., and 214mm. It will be observed that the 
cells reach their maximum at the fourth stage, about which 
time the gall is rapidly maturing. From this time, less and less 
secretion is poured out, and the linings of the cavities begin to 
lose their green appearance, gradually becoming yellowish 
brown, dry, and hard. Further, the larval form rapidly 
changes. The abdomen increases in size, becoming globose, 
while the head and thorax show only small increase. This is 
in striking contrast to the early stages. A larva of the fifth 
stage, measuring 214mm., when placed on glass or any foreign 
substance excretes practically no fluid. 
