40 



TJie Larva of Chironomiis 



the yolk. In Hydroids, in Echinoderms, and even in 

 vertebrates, cells are known to detacli themselves 

 from an epithelium and to wander about the body, 

 afterwards arranging themselves into an epithelium 

 again ^ 

 Oenocytc?. Closely associated with the epidermis of the Chiro- 

 nomus-larva are some peculiar cells, named oenocytes by 

 Wielowiejski^ from their colour, which is that of yellow 

 wine (figs.30, 31). The oenocytes are of two sizes, one much 

 larger than the other. The large ones occur only in the 



Fic. 31. — Oenocytes and outer fatty layer, as seen in third abdominal 

 segment of living larva, c, cuticle, a, group of oenocytes. &, solitary 

 spherical oenocyte in front of the group, r, outer fatty layer, m, muscles 

 in transverse section. 



a^bdominal segments, rather nearer to the ventral than to 

 the dorsal surface. They form paired and segmentally 

 arranged groups of four cells, which are often, but not 

 uniformly, arranged in a lozenge close together. The 

 cells are oval, nucleated, and attached to the epidermis 

 by threads of protoplasm and fine tracheal branches. 

 The nucleus may occupy nearly half the diameter of the 

 cell, but is sometimes much smaller. The colour is due, 

 according to Wielowiejski, to minute granules ; no oil- 

 drops are present. There is also a fifth cell, of spherical 



' Kleinenberg, 1886, p. 6 ; Met.schnikoff, 1885. 



1886. 



