290 Annals EntonwJogical Society of America [Vol. XI, 



far as the rectum, and forms a complete membranous cylinder 

 around the digestive tube. As is the case with all of the muscles 

 of the alimentary canal of this insect (and probably of all 

 others), they are clearly striated. 



THE CROP. 



Transition. The transition from the oesophagus to the crop 

 is gradual. The lumen grows gradually wider, the epithelium 

 becomes thinner and more stretched, and the chitinous folds 

 become less and less pronounced as one traces the oesophagus 

 posteriorly. 



Intima. The intima is very much thinner than in the 

 oesophagus, and while it is thrown into many minute wavy 

 folds, the six large primary folds have disappeared entirely. 

 Both primary and secondary intima may be recognized; they 

 are of the same nature as the corresponding structures in the 

 cesophagus, but are much more delicate. 



EpitheJiiim. In both cross and longitudinal sections, the 

 cells appear as if they were stretched; their bases are long, and 

 their altitude low, so that instead of being cuboidal, they 

 present the aspect of long, narrow rectangles. The oval, 

 granular nuclei stain quite deepl}^ but are not as chromatic as 

 those in the pharyngeo-oesophageal epithelium. The cytoplasm 

 is homogeneous, non-granular and non-vacuolar. 



As in the rest of the fore-intestine, a fibrillar area is devel- 

 oped between the epithelium and the intima previous to each 

 molt. It is much less extensive than in the pharynx and 

 oesophagus, probably because the thin, little folded intima 

 is shed much more easily than the thick, strongly folded intima 

 which lines the other regions. 



A cross-section through the crop is illustrated in figure S. 



Basement membrane. A well developed basement membrane 

 is present. 



Longitudinal muscles. The longitudinal muscles are repre- 

 sented by isolated striated fibres, which continue anteriorly 

 into the pharyngeo-oesophageal region, and posteriorly into 

 the ventriculus. 



Circular muscles. The circular muscles are much stronger 

 than the longitudinal fibres. They appear to be continuous 

 with the muscles of the oesophagus anteriorly and with those 

 of the ventriculus posteriorly, since they all lie in the sam^ con- 

 nective tissue sheath. 



