THE (ENOCYTES 



423 



c. The oenocytes 



These cells (Fig. 386), with the exception of the eggs, are the 

 largest in the body, and occur in most if not all winged insects. 

 They were called oenocytes (oinos, wine ; kustis, cyst), by Wielowiej- 

 ski in allusion to their wine-yellow color. These cells are arranged 

 segmentally (Fig. 387) in clusters, held in place by tracheae, and are 



situated mostly on each side of the ab- 

 domen, rarely being found in the adjoin- 

 ing parts of the thorax. They are more 

 or less intimately associated with the blood 



FIG. 386. Cluster of oenocytes from a nearly mature 

 Phryganeid larva: o, oenocytes; t, large tracheal branch; it, 

 smaller tracheal ramifications ; h, tracheal hypodermis. 



and fat-body. Unlike the fat-body, how- 

 ever, they arise in embryonic life from the 

 ectoderm, either by delamination or by 



FIG. 387. A nearly mature immigration, lUSt behind the tracheal in- 

 embryo otXiphidium ensiferum : 

 o, o, oenocyte clusters seen from the volutions, 

 surface through the integument; 

 a, pleuropodium of the right side 



The separate cells of each cluster are usually 

 separate, but in rare cases may fuse in pairs or 

 form smaller clusters. In shape they are round 

 or oval, often sending out pseudopodia-like processes, by which they are 

 attached to the tracheal twigs or to each other. "The cytoplasm, which is very 

 abundant, is full of yellowish granules and is sometimes radially situated 

 towards its periphery. The large spherical or oval nucleus contains a densely 

 wound and delicate chromatic filament." (Wheeler.) 



Graber first pointed out the identity of these clusters of cells with certain 

 metameric cell-masses in insect embryos, observed by Tichomiroff in those of 

 the silkworm, and by Korotneff in the embryo mole-cricket. 



Although they resemble the blood corpuscles in some insects, they are always 

 much larger, and do not seem to be amoeboid, while they are never seen to 



(appendage of the first abdominal 

 segment); , styli; c, cercopods. 

 This and Fig. 386 after Wheeler. 



