NO. 2 RECOGNITION AMONG INSECTS — McINDOO '^'J 



Judging from the morpholog>', we may reasonably conclude that 

 the gland cells secrete a substance throughout their cytoplasm. This 

 substance collects in the ampulla which serves as a reservoir, and 

 from the ampulla the secretion passes through the chitinous tube to 

 the exterior where it runs into the pouch. That the gland cells 

 secrete an odorous substance is shown by the fact that when the 

 articular membranes forming the pouches are excised, they appear 

 wet and give off the characteristic bee odor, while the other articular 

 membranes neither appear wet nor emit an odor. This view is 

 further supported by the following: A virgin queen, emitting a 

 very sweet and pleasant odor, was severed between the thorax and 

 abdomen ; when tested the thorax did not emit the sweet odor, while 

 the abdomen did. The abdomen was then split into dorsal and ventral 

 halves, and when tested only the dorsal half gave off the sweet odor. 

 The dorsal half was next severed between the fourth and fifth terga, 

 and in this case the portion containing the last two terga emitted a 

 sweeter odor than did the other portion. 



The groovelike indentations in the chitin forming the pouch may 

 serve two purposes : ( i ) To give more flexibility to the chitin, and 

 (2) to retain the volatile secretion and to help prevent a too rapid 

 evaporation of it. So long as the abdomen is straight, the pouch is 

 well protected and the liquid can not evaporate rapidly, but when the 

 abdomen is considerably bent, the entire pouch is more or less exposed 

 to the outside air. 



The gland cells in old workers and queens are highly developed 

 and are proportionately the same size, but the size of them increases 

 little after the bees have emerged, and not until a few days later 

 do they function in full capacity, judging from the fact that the 

 odor emitted by workers just emerged gradually becomes more pro- 

 nounced up to the fifth or sixth day. 



The present writer failed to find gland cells connected with 

 the articular membranes in the abdomens of drones, but they were 

 not looked for elsewhere, and it is possible that some kind of a 

 scent-producing organ may yet be found in drones. This assumption 

 seems reasonable for sometimes when the abdomens of young drones 

 are slightly squeezed, a very thin and whitish liquid may be seen 

 on the abdominal articular membranes. At other times a clear liquid 

 may be observed on the articular membranes between the fourth and 

 fifth, and fifth and sixth abdominal terga ; and it has already been 

 stated that drones emit a faint sweetish odor. 



