514 K. N. PAVLOVSKY AND E. J. ZARIN 



part of the surface of the transverse section of the libre {I'i. 17, 

 tig. 15, mj) at the point where the sarcoplasrn and nuclei are 

 scarce, and half the diameter of the fibre where the sarcoplasrn 

 and nuclei are strongly developed. The nuclei always lie in the 

 sarcoplasrn nearer to the periphery of the muscle-columns 

 (PI. 16, tig. 14 ; PI. 17, fig. 15, 16, sp), and not between the latter 

 as in the analogous membrane of the small intestine (PI. 17, 

 hg. 18). 



Hind -gut. 



The hind-gut is divided into two parts — both in its anatomical 

 and histological structure — the anterior — small intestine (PI. 15, 

 fig. 3 ; PI. 16, fig. 4, it), and posterior — large intestine (Pi. 16, 

 fig. 4, /•). 



Small Intestine. 



The structure of the small intestine has already been estab- 

 lished by previous investigators. We may add to these some 

 details in the microscopical structure of its single-layered 

 cylindrical epithelium. The cells of the latter are covered on 

 their interior surface by a thick chitinous cuticle. The proto- 

 plasm of the cells is divided into two portions, the exterior — 

 granular (PI. 17, hg. 17, d), and interior — characterized by a 

 rod-line striation (PI. 17, fig. 17, ds). 



The fairly large rounded nucleus (n) lies nearer to the base 

 of the cell. Interiorly to it in the layer of granular plasm are 

 found large vacuoles with granules of secretion {vs). Both 

 the protoplasm and secretion of the epithelium of the small 

 intestine are oxyphil. 



The basilary membrane of the intestine (PI. 17, fig. 17, mb) is 

 surrounded by circular muscle-fibres anastomazing with each 

 other. They are thick and their nuclei are disposed along the 

 axis of the fibres surrounded from, all sides by bundles of 

 myofibrils (PI. 17, fig. 18, cmf). 



In general the small intestine of the bee is characterized 

 by the glandular character of its epithelium. The structure 

 of the intestine described may serve as evidence either of its 

 glandular function or of processes of absorption taking place 



