36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 68 



certainly is not a good source of odors for insects. At first thought 

 it might be argued that the blood of insects serves as a source for 

 all odors, for the blood of dififerent insects probably gives off slightly 

 different odors, but it has never been shown that the blood of insects 

 actually comes to the surface of the body ; that the blood comes to 

 the surface is more impossible for insects, owing to their chitinous 

 covering, than it is for the higher animals. Of course devices for 

 the blood to come to the surface might have been evolved, but after 

 understanding the structure of the various types of scent-producing 

 organs it will be seen that a much better specialization has been 

 brought about, and instead of an insect pouring its vital fluid upon 

 its external surface, gland cells have been evolved to extract the 

 best constituents from the blood to serve as a source for odors ; 

 according to this specialization a smaller amount of liquid is required, 

 because its volatility and ability to produce effective odors has been 

 many times increased. 



A. Scent-Producing Organ of Honey-Bee 



It is reported that Nassonoff first described the morphology of 

 the scent-producing organ of the honey-bee. His original work in 

 Russian can not be had here, but acording to Zoubareff (1883), 

 Nassonoff did not describe the structure of this organ as seen by 

 the present writer (1914), and he suggested that the gland cells of 

 the organ produce perspiration. Sladen (1902) called this organ a 

 " scent-producing " organ, but did nothing more than to describe the 

 articular membrane between the fifth and sixth abdominal terga 

 (propodeum not counted) of worker bees. 



Externally this- organ appears as a white transverse stripe near 

 the distal end of the abdomen, but is visible externally only in worker 

 bees that are fanning, however, it is present in all workers and 

 queens, but has never been found in drones. The white stripe is 

 the articular membrane and it is so folded that it forms a pouch 

 which encircles about one-half of the abdomen and terminates on 

 either side of the abdomen just above the articulation of the tergum 

 and sternum. Just beneath the pouch lie many unicellular glands, 

 each of which is connected with the bottom of the pouch by means of 

 a chitinous tube through which the secretion passes into the pouch. 

 The gland cells are modified hypodermal cells ; they are granular and 

 have conspicuous nuclei which contain many globular, refractive 

 bodies. Each chitinous tube arises in the cell at the center of a clear 

 area, the ampulla, which contains many radial streaks. 



