144 Beekeeping 



honey-stomach, and furthermore, as is shown later, the 

 contents of the ventriculus could not escape were this con- 

 tortion possible. Cheshire claims that the hooks (at nn, 

 Fig. 61) of the pro ventriculus serve to separate the honey 

 and pollen in the honey-stomach, but no proof is presented. 

 The only known function of the proventriculus is that of 

 opening to allow food to pass to the ventriculus. There 

 is no evidence that it assists in the mastication of pollen. 



Behind the proventriculus is the ventriculus (Vent), a 

 thick-walled organ, ringed by numerous constrictions. It 

 consists (Fig. 77) of longitudinal and transverse muscles 

 surrounding a much folded epithelium, the cells of which 

 are supposed to produce some of the digestive enzymes. 

 The inner depressions of this epithelium are filled with a 

 gelatinous mass (pp) which extends into the lumen. The 

 food contents of the ventriculus are surrounded by layers 

 of membrane (peritrophic layers, Fig. 77, Pmb), formed 

 from the gelatinous mass in the enveloping epithelium. 

 The peritrophic layers are often described as chitinous but 

 this, according to Petersen, is an error. These membranes 

 do not seem capable of allowing the passage of the food con- 

 tained in them to the ventriculus wall and probably little 

 or no absorption of food occurs here. Furthermore, pollen 

 is usually found at the posterior end undigested and, ac- 

 cording to Snodgrass, it is not prepared for absorption 

 until it reaches the rectal ampulla. Snodgrass observed 

 in certain parts of the ventriculus wall a sloughing off of 

 the ends of the epithelial cells (Enz), presumably enzymes, 

 which are seen in the gelatinous peritrophic mass. Petersen, 

 in confirmation of this view, found that the peritrophic 

 layers (which come from the peritrophic mass on the epithe- 

 lium) are not chitinous but contain proteolytic ferments. 

 The peritrophic layers and their attachment to the pro- 

 ventricular valve effectually prevent the regurgitation 

 of the contents of the ventriculus into the honey-stomach. 

 The contents of the ventriculus does not at all resemble 

 larval food. It therefore appears clear that the theory that 



