530 K. N. PAVLOVSKY AND E. J. ZARIN 



capable of not producing invertasc in detinite conditions. 

 At any rate, as is seen from the table, the tested extracts of 

 the same concentration manifest different activity. 



If circumstances allow we shall dedicate special experiments 

 to the solution of the question discussed. 



A further examination of the data adduced in the table 

 shows that only extracts from the stomach possess considerable 

 power of preventing the rotation of the polarization plane in the 

 suijjar solution, whereas those from the crop, small and large 

 intestines, are either altogether inactive or act very weakly. 

 E\idently these latter portions of the intestine do not produce 

 invertase, the latter penetrating there from the stomach 

 together with the food. 



In experiments nos. 0, 7, S, 19. and 22, invertase was deter- 

 mined in extracts prepared immediately from the crop, small 

 and large intestines, the alteration in the rotation of the 

 plane of polarization being insignificant. 



Tims we have arrived at conclusions coinciding with Axen- 

 feld's opinion regarding the place in which invertase is pro- 

 duced, i.e. that it is produced in the stomach of the bee. 



The data of Erlenmeyer and Planta, according to which 

 greater activity ^^as manifested by extracts from the head 

 and abdomen of the bees than from their thorax, may be 

 explained as follows. 



The origin of invertase from the abdomen should be referred 

 to the stomach of the bee. The greater activity of the extract 

 from the head of the bee, as compared with that from the 

 thorax, is explained by the fact that the salivary glands lying 

 in the head produce invertase, whilst those lying in the thorax 

 do not produce this ferment. Such an explanation is, of course, 

 only probable, and must be verified by special investigations. 



After having ascertained the general relations exliibited by 

 invertase in the ventriculo-intestinal tract of the bee, we have 

 also conducted several preliminary experiments with the view 

 of a special stud}^ of the nature of this ferment. 



Thus it was interesting to determine the influence of the 

 method of preparation of the ferment on the activity of inver- 



