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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 proventriculus 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 
