The Life Processes of the Individual 143 



for criticism. There have been, however, very few in- 

 vestigations of the digestive processes. The digestion of 

 insects is discussed by Biedermann, 1 and more recently 

 Petersen 2 has published a discussion of the processes of 

 digestion in the honeybee. This is the first good paper on 

 this subject and the author is to be commended for taking 

 a stand against the making of comparisons with human 

 physiology. 



The mouth parts have already been described (p. 135), 

 and those glands (1GI, Fig. 59) which are supposed to be 

 concerned in the production of larval food have also been 

 discussed (p. 111). Behind the mouth is an enlargement 

 of the alimentary canal called the pharynx (Phy, Fig. 60), 

 leading to a long narrow tube extending through the thorax, 

 the oesophagus ((E). Behind the constriction between 

 the thorax and abdomen, the alimentary canal widens to 

 form the honey-stomach (HS), homologous to the crop of 

 other insects. This is a thin-walled, muscular organ used 

 by the worker in carrying nectar to the hive. Behind the 

 honey-stomach is a valvular structure, the proventriculus 

 (Pvent, the anterior part being often called the stomach- 

 mouth) which separates the honey-stomach from the ven- 

 triculus (often called the chyle stomach). The proven- 

 triculus is of special interest in the bee, since when closed it 

 prevents the nectar from mixing with the contents of the 

 ventriculus and makes it possible for the honey-stomach to 

 function as a carrying vessel. It is claimed by Schonfeld 

 that the anterior end of the proventricular valve (nn, Fig. 

 61) may be moved forward to touch the posterior end of 

 the oesophagus, so that the contents of the ventriculus 

 may be forced out as larval food. Snodgrass has shown 

 that this cannot happen without tearing the muscles of the 



1 In Winterstein's Handbuch der vergleichenden Physiologie, vol. 2, 

 Heft I. 



* Petersen, Hans, 1912. Beitrage zur vergleichenden Physiologie der 

 Verdauung. V. Die Verdauung der Honigbiene. Pniigers' Arch, fur die 

 gesammte Phys. d. Menschen u. d. Tiere, XLV, pp. 121-151. 



