104 THE ANATOMY OF THE HONEY BEE. 



separates itself from the ends of the remaining epithelial cells, which 

 at the same time secrete a new intima over their inner surfaces. The 

 lower part of figure 4G A shows this indisputably. The whole thing, 

 then, finally contracts about the food and, as the digestive cellules 

 give up their contents, shrivels and shrinks and becomes a peritrophic 

 membrane. In figure A the outermost peritrophic layer is still in 

 both conditions — its dorsal part is shrunken to a thin membranous 

 form, while its lower part is gelatinous and filled with secretion 

 cellules, though it is separated from the epithelium by a new intima 

 and is detached at intervals from the latter. Beneath the new intima, 

 furthermore, is seen at places the formation of a new gelatinous mass. 

 Some of the inner peritrophic layers shoAvn in A also retain remnants 

 of cells. 



Figure 46 A is drawn from a specimen which is typical of all in 

 several series of sections through the ventriculus. The peritrophic 

 layer partly adhering to the epithelium is no artifact, because the 

 same condition may often be directly observed in dissections of fresh 

 specimens. In the opposite end of the series from which the specimen 

 was selected this layer is entirely free from the epithelium. 



The peritrophic membrane has been described in some insects as 

 being a prolongation from the intima of the pxoventriculus, the ven- 

 triculus itself being supposed never to secrete an intima. It is per- 

 fectly conceivable that the anterior end of the membranes might be 

 generated by the outer cellular layer of the proventricular funnel and 

 remain attached to it after the rest of it had become free from the 

 ventricular wall, and thus give the appearance of belonging to the 

 proventriculus. The writer, however, has several sets of longitudinal 

 sections through these parts in the bee, but none of them nor any dis- 

 sections made show such a condition. 



Absorption is commonly supposed to take place largely in the ven- 

 triculus. If so, the food must pass through the several peritrophic 

 membranes and then through the thick epithelium. It is entirely 

 possible that it may do so, but the pollen contained in the ventriculus, 

 as already stated, shows little or no evidence yet of digestion and does 

 not begin to do so until it reaches the small intestine. On the other 

 hand, the dark mucilaginous slime of the ventriculus does not appear 

 in any quantity in the much drier contents of the small intestine. 

 Therefore it may be supposed that this slime contains the sugar ele- 

 ments of the food and that the latter are principally digested in, and 

 absorbed from, the ventriculus. The absorption of the proteids and 

 hydrocarbons must take place in the intestine and rectum since these 

 food elements in the bee's diet are derived only from the pollen. 

 However, these conclusions are ])urely tentative, being based on the 

 writer's observation of the contents of the different parts of the ali- 

 mentary tract, which, while fairly extensive and continued through 



