Oenocytes 



4^ 



shape, lying in front of the group ; according to Wielo- 

 wiejski it always contains two nuclei, one large and 

 central, the other very small and peripheral ^ ; it is 

 more distinctly granular than the grouped cells. The 

 twelfth segment (ninth abdominal) has no group of four 

 cells, but one pair of spherical cells, and also a single cell 

 at the base of each anal foot. The large oenocytes do 

 not occur in young larvae, though they are conspicuous in 

 those which are full-grown ; they persist in the pupa 

 and imago, but undergo some reduction in size. Accord- 

 ing to Graber (1891) the oenocytes are developed from 

 the ectoderm. 



Fig. 32. — A solitary 

 spherical oenocyte, 

 with contained gra- 

 n\iles. 



Fig. li. — Small oenocytes, attached 

 to inner face of epidermis, i, svirface 

 view. 2, section. 



The small oenocytes are very numerous on the inner 

 surface of the epidermis of the last thoracic and the 

 abdominal segments, especially towards the ventral 

 surface. They contain yellow granules, like those of 

 the large oenocytes, and often occur in pairs. Both 

 readily stain with carmine. 



Oenocytes occur in Culex, Corethra, and many other 

 Diptera, and also in insects of other orders (Wielowiejski). 

 Nothing has been definitely ascertained respecting their 

 function. "Wielowiejski points out their resemblance to 



1 The same is true of Phalacrocera (^Miall and Shelford, 1897, pi. xi, 

 fig- 33)- 



