The Life Processes of the Individual 147 



stomach. However, pollen contains no starch so that the 

 breaking down of starch plays a small part in the digestion 

 of the bee. 



The next important constituent of bee food is proteid, 

 derived from pollen. Petersen shows the presence of pro- 

 teolytic ferments in the salivary gland secretions and es- 

 pecially claims that the layers of peritrophic membrane 

 consist largely of such ferments. He also makes the in- 

 teresting observation that the bee is incapable of digesting 

 the proteid from pollen unless the grains are broken before 

 they enter the ventriculus, any ones remaining unbroken 

 simply passing out in the feces. It would therefore seem 

 probable that the pollen is surrounded in the ventriculus 

 with the peritrophic layers containing the ferments and is 

 then passed on to the small intestine without being broken 

 up or absorbed. The use of pollen is more in evidence 

 during brood-rearing and it is usually assumed that the 

 workers predigest this, or perhaps more correctly, secrete 

 a mixture rich in protein for the use of the larvae. However, 

 since the mid-intestine of the older larvae contain consider- 

 able pollen, a large part of their proteid digestion is by their 

 own proteolytic ferments. 



Pollen contains considerable oil but Petersen failed to find 

 that any of it is digested by the bee, at any rate most of it 

 passes through without being broken up or absorbed. 



The retention of feces by bees, so long as they stay in the 

 hive, except when dysentery develops, is of importance 

 in their management. The relation of this retention to 

 the activities of bees in winter is discussed in a previous 

 chapter (p. 91). Usually during the active season, when 

 feces accumulate most rapidly, there are frequent opportu- 

 nities for flight and the ejection of feces. 



For bees living only on honey or perhaps on a syrup of 

 cane sugar, digestion is reduced to a minimum. It remains 

 to be proved whether under such conditions the bees are 

 fully nourished. That bees can live over winter without 

 pollen is of course not proof that they do not need it then. 



