554 ANTHON. [Vo. XIX. 
Along the heart on the basal side and along the alary 
muscles occur the so-called pericardial cells, which from their 
position would seem to have a close relation to the circulation 
of the blood. Some cenocytes are at times found collected 
along the body wall in the posterior region, as described by 
Bengtsonn. According to Kowalevsky the function of the 
pericardial cells is to remove the foreign or injurious matter 
mingled with the blood. The pericardial cells themselves are 
elliptical in shape and with no easily distinguished cell wall. 
They often have two nuclei lying side by side in the cytoplasm 
and sometimes as many as four without any sign of a sepa- 
rating cell wall. The cell-nuclei stain very heavily, but show 
no distinct chromatic filaments. The pericardial cells are con- 
gregated about the sides of the heart and lie along the alary 
muscles for some distance from the heart. 
The blood proper is a thin whitish fluid which contains the 
very pale oval corpuscles. These corpuscles have a rounded 
nucleus and are covered with fat globules. The fresh blood 
has a slightly alkaline reaction. These leucocytes are seen in 
great numbers at the posterior end of the heart, just in front 
of the stigmata. At the stigmata the blood is passed over the 
tracheal ramifications, so that it tends to traverse the normal 
condition in insects in which the air is always brought to the 
blood; while here the blood seems to be brought to the air. 
VIII. THe FAtT-BODIES. 
The alimentary canal is nearly enclosed in the thin sheet 
of adipose tissue, which is perforated by many small holes. 
This tissue fills in the space between the other organs and so 
occupies a large part of the body cavity. The cells are regu- 
larly polygonal in shape, and possess a central oval nucleus. 
(Figs. 40 and 41.) The fat-bodies are probably reserve food 
material to be used during the rapid pupal metamorphosis, as 
the sheets of adipose tissue are very large and conspicuous in 
larvee which are about to pupate. When the larvz have been 
kept for some time without any adequate food supply the fat- 
bodies are gradually absorbed. 
