146 
Beekeeping 
where the ventriculus and small intestine join, the Mal¬ 
pighian tubes (Mai) empty into the alimentary canal. 
The small intestine is coiled and finally empties into the 
rectal ampulla (Red, rectum or large intestine). The inner 
epithelium of the rectum is thrown into six longitudinal 
folds, the so-called rectal glands (Fig. 77, RGl) of unknown 
function. It is usually believed that they increase the 
absorbing surface but, since they are covered on the inner 
surface with chitin, this explanation seems improbable. 
The rectal ampulla is capable of considerable expansion 
and normally retains the feces when bees are confined to 
the hive, as in winter. It is supposed that most of the 
absorption of food takes place in the hind-intestine. Peter¬ 
sen advances the fantastic theory that the rectal glands 
are the source of the hive odor. 
The food of bees which must be acted upon by the various 
digestive juices to be prepared for absorption have their 
origin in the nectar and pollen collected from flowers. The 
chief food is honey, which consists largely of invert sugar. 
This name is given to a mixture of two sugars, levulose and 
dextrose, which by various means can be made from sucrose 
(cane sugar). In the higher animals, these sugars are ca¬ 
pable of absorption without further change, and this is pre¬ 
sumably true of bees also. The sugar in nectar is probably 
sucrose with some invert sugar. The preparation of this 
material for absorption therefore begins with the ripening 
of nectar into honey. As explained earlier (p. 85), this is 
by the action of an enzyme and, according to Petersen, 
such an enzyme was extracted from the head of the bee by 
Erlenmeyer and by v. Planta, presumably from the salivary 
glands. The absorption of sugars probably occurs in the 
ventriculus and any water in the honey which is not needed 
is ejected. The process of such an ejection is not clear. 
It is also stated by Petersen that the bee produces a diastatic 
ferment by which the digestion of starch is possible, but he 
was never able to prove from experiments that starch is 
changed into dextrin, maltose or dextrose in the honey- 
