1914.] NATURAL SCIENCES OF PHILADELPHIA. 551 



of which is located in the articular membrane between the fifth and 

 sixth and the other between the sixth and seventh abdominal terga. 

 These pouches are not lined with hairs. The tubes from the uni- 

 cellular glands carry the secretion directly to the pouch where it is 

 forced to the exterior by muscles constricting the lumen of the pouch 

 (Oettingcr, 190()). In the female moth Orgyia anliqua the scent- 

 producing organ is a shallow pouch in the articular membrane 

 between the eighth and ninth abdominal terga. The unicellular 

 glands lie in groups like several bunches of grapes just beneath the 

 thin membrane. Freiling (1909) saw no tubes connecting the 

 gland cells with this membrane. He thinks that the secretion 

 passes through the membrane by infiltration. In the petiole of 

 the worker ant of Myrmica rubra, Janet (1898) found an invaginated 

 chamber. At the bottom of the chamber may be seen the exits of 

 the tubes which lead to the launch of unicellular glands. He also 

 found in the same ant two small groups of unicellular glands beneath 

 the articular membrane between the ninth and tenth abdominal 

 terga. These glands are also connected with tubes which run to 

 the exterior. Both of these organs may possibly be scent-producing 

 organs. The wax glands of young worker l^ees may also have such 

 a function. Each of these unicellular glands is nothing more than 

 a hypodermal cell modified for secreting a substance which passes 

 through many minute pores in the thick chitin of the abdominal 

 segment. After coming in contact with the external air the substance 

 changes to wax. In Apis these glands lie beneath the second, 

 third, fourth, and fifth al)donnnal sterna, in Melipona beneath the 

 last four abdominal terga, in Trigona beneath the last five abdominal 

 terga, but in Bombus beneath both the abdominal sterna and terga 

 (Dreyling, 1906). 



The scent-producing organ of the honey bee belongs to the fourth 

 type, and it is probably the most highly developed organ of this type. 

 Nassonoff thought that the chitinous tubes ran into the bottom of 

 the canal, chiefly formed by the anterior portion of the articular 

 membrane, instead of them uniting with the posterior wall of the 

 canal. If they united with the bottom of the canal, they would 

 materially affect the flexibility of the membrane. Zoubareff (1883) 

 imagines that the gland cells in this organ of the bee secrete the 

 little drops of liquid which bees are said to let fall when flying. He 

 thinks that these drops represent the excess of water contained in 

 freshly gathered nectar over that in ripened honey. 



In regard to storing and discharging the secretion as a means of 



