THE ALIMENTAEY CANAL AND ITS GLANDS. 99 



The ventricular contents do become slightly milky when treated with 

 a solution of tartaric acid, but they are not changed into anything 

 at all resembling royal jelly. Moreover, a transformation of the 

 brown slimy contents of the ventriculus into the white gummy paste 

 on which the larvae are fed does not seem possible without the addi- 

 tion of much other material. In fact the added material must make 

 up the conspicuous part of the larval foodstuff and, from a purely 

 argumentative standpoint, it would not seem necessary to assume that 

 it contains any " chyle " at all. Again, if it were not for Schonfeld's 

 experiments one could not easily believe that the food could be dis- 

 gorged through the proventricular valve. The conspicuous action of 

 the proventricular mouth is a swallowing motion, and the writer has 

 not been able to induce the ventriculus to disgorge its contents 

 through it in the way that Schonfeld describes, although perhaps 

 suiEcient care was not observed in exposing the organs. Cheshire 

 states that. the proventricular tube (fig. 45, PventVlv) in the ventricu- 

 lus " rather makes regurgitation improbable than impossible," while 

 he argues that the down-pointing bristles of the stomach-mouth would 

 further interfere with this process. Cowan adopts the view of 

 Dufour and Schonfeld that the brood food is of ventricular origin, 

 and says in this connection: ''Although saliva from the glands 

 (especially System I) is probably added to the food, this can not, 

 from its great variability, be entirely a secretion, as stated by 

 Schiemenz. The work of Doctor Planta, we think, conclusively proves 

 that the food is not a secretion, and that the nurses have the power 

 of altering its constituents as may be required for the different bees." 

 If the variation of the food is under the control of the workers pro- 

 ducing it, it does indeed look impossible that it should be produced ' 

 entirely by glands. Cov/an illustrates by a diagram how regurgita- 

 tion through the proventriculus may be possible in spite of the pro- 

 ventricular tube projecting into the ventriculus. Since this tube is 

 simply a cylindrical fold its walls, as shown in figure 45, PventVlv, 

 consist of two layers, and Cowan says that " when the bee wishes to 

 drive the chyle food from the chyle-stomach (Vent) into the cells 

 it forces the stomach-mouth {nn) up to the oesophagus {(E) and the 

 prolongation {PventVlv) unfolds, extending the chyle-stomach to the 

 oesophagus, making a direct communication through which the food 

 is forced by compression of the chyle-stomach by its muscles." The 

 honey-stomach of the worker is much larger than that of the queen, 

 shown by figure 45, in which there is not enough space for the unfold- 

 ing of the proventricular tube. This mechanism suggested by Cowan 

 looks simple and conclusive in a diagram, but when one attempts to 

 unfold the proventricular tube by grasping the stomach-mouth in a 

 pair of fine forceps and pulling the top of the proventriculus upward 

 it is found that, while the tube can be entirely straightened out, doing 



