No. 480] BLOOD GILLS OF SIMULIUM 



without apparent structure. The epithehuni is a layer 

 in thickness from 5/t to 18^, composed of large, distinct, so 

 flattened cells well filled with cytoplasm, and containing? 

 single large nucleus, in which the nucleolus and chroniatii 

 ings are very distinct. The chromatin occurs tliroui^lic 

 nucleus but is distributed a little more ilnckl,\ around il 

 phery (Fig. 3, A and C). The basement uicnibn.nc v 

 and much like that found under the li\ [mm. i im . 1 i^. 



At the point of union be 

 tween the body wall and tlit 

 rectum there is a marked (1» 

 crease in the thickness of tin 

 layers, the intima and epitiieli 

 um being much more delicat( 

 than the cuticle and hypoder 

 mis; and this condition u 

 continued to a point 



