ALIMENTARY CANAL IN THE BEE 529 



in experiments no. 1 and no. 2 the difference between the 

 control and experimental solutions in this respect is so insigni- 

 ficant (0-07° and 003°) that it may be ascribed to error in 

 analysis, and it is impossible to draw any definite conclusions 

 from it. However, the great activity of invertase in the remain- 

 ing experiments points to the absence of this ferment in the 

 extracts tested in the experiments discussed. It is characteristic 

 that in regard to the remaining ferments (amylase, inulase, 

 lactase, lipase, pepsin, trypsin, and chimosin) there is no 

 essential difference between these two and the remaining 

 experiments. 



As is seen from the table the two experiments named were 

 conducted late in autumn and early in spring when the bees 

 were in the stage of winter rest and fed on honey which, as is 

 known, consists chiefly of inverted sugar and contains no 

 saccharose at all, or contains it in insignificant quantities. 

 The significance of invertase both in the animal and plant 

 kingdoms lies in its capacity of converting saccharose into 

 inverted sugar directly assimilated by the protoplasm. 



Since the ferment is produced by the cells chiefly when the 

 organism requires it, the absence of invertase in the first two 

 experiments are provisionally explained by the fact that the 

 bees feeding in winter on inverted sugar are not in need of it, 

 and do not therefore produce this ferment. 



Cases in which the same organism is capable, according to 

 conditions, of different ferment-productive activity are not 

 rare ; sometimes the presence of a definite substance specific 

 to the given ferment is quite sufficient to activate it. 



Thus, according to Oppenheiiner, some mucorines produce 

 no ferments when cultivated in media containing substances 

 assimilated by them directly. However, on addition of proteins 

 to the medium the same mucorine produces proteolytic fer- 

 ments on addition of starch-amylase, &c. 



The investigations of Brown and Moris have shown that the 

 germ of malt does not produce amylase if the grains are culti- 

 vated in media containing sugars capable of assimilation. 



Therefore, it is possible that the organism of the bee is also 



