540 K. N. I'AVLOVSKY AND E, J. ZARIN 



and from its contents contained no catalase, whilst the extract 

 from the wall of the posterior part of the dif^estive tract alone 

 contains this ferment, the inevitable conclusion is that catalase 

 is produced by the rectum itself in the bee, and is not brought 

 there from other parts. 



Now the question arises, in what part of the rectum is this 

 ferment produced ? In the first part of the work the structure 

 of the rectum was described in detail, and it was mentioned 

 that the latter differs in structure from the crop of the bee in 

 the presence of eight elongated rectal glands. The wall of both 

 rectum (PI. 17, tig. 20, ep) and crop (PI. 16, tig. 5, ep) is formed 

 by tiat epithelium bearing no characters peculiar to glandular 

 tissue. Therefore it is difficult to ascribe to it the property 

 of producing ferments ; and, indeed, in the crop they are never 

 produced. It may therefore be naturally concluded that the 

 place where catalase is secreted is presented by the rectal glands 

 in the plump epithelial cells of which are found granules of 

 zymogen (PI. 17, fig. 21, ep). The correctness of such a conclu- 

 sion stands somewhat in contradiction to the fact that catalase 

 may also be produced by non-glandular tissue. Thus this 

 ferment is present in the nerve-tissue of some animals. In 

 the near future we shall endeavour to solve the question 

 discussed more precisely. In the dilated rectum of the bee 

 it is possible to separate the anterior part with the rectal glands 

 from the posterior consisting only of flat epithelium. 



An investigation of the extracts from these parts of the 

 rectum will, possibly, be able to give a definite answer to the 

 question regarding the role of the rectal glands which have 

 hitherto been mysterious organs in insects. Concerning their 

 role only suppositions have hitherto been expressed. Berlese 

 supposes that these glands serve to absorb the remains of food, 

 and there may be also present some kind of valve for the retention 

 of the contents of the intestine previously to the final formation 

 of the faeces. N. A. Cholodkovsky (1912) thinks that it is 

 possible to speak only of a sort of excretive function of the 

 rectal glands, under the cuticle of which in Lepidoptera and 

 the cricket (Gryllus domesticus) he observed an accumu- 



