146 



THE BIOLOGY OF INSECTS 



V.d. 



vas deferens. The paired vasa deferentia lead into a median 

 chitin-lined ejaculatory duct, which corresponds to the 

 female's vagina, and has associated with it a seminal vesicle, 

 wherein the sperms often complete their development and 



await the act of pairing, as 

 well as accessory glands ; 

 these secrete a fluid by which, 

 when partially evaporated, 

 the sperms are united in the 

 bundles ready for transference 

 to the sperm reservoir of the 

 female (Fig. 37). In many 

 insects, the drone hive-bee, 

 for example, these accessory 

 glands are of relatively enor- 

 mous size. 



In order to ensure trans- 

 ference of the sperms to the 

 female's spermatheca, male 

 insects are furnished with a 

 cuticular genital armature, 

 corresponding to the female's 

 ovipositor, and used for grasp- 

 ing the female's abdomen in 

 the act of pairing. The 

 ejaculatory duct terminates 

 in an intromittent organ 

 (aedeagus) which may be 

 simply tubular as in bristle- 

 tails, or provided with a 

 basal bulb and a set of paired 

 outgrowths as in bees and 

 flies. Pairs of processes on the 

 After Carpenter eighth and ninth abdominal 

 segments or on one of 

 these, serve as claspers working laterally, while the terminal 

 dorsal and ventral plates of the abdomen may be modified 

 into vertically disposed claspers. It is instructive to 



Fig. 37. — Male Reproductive Or- 

 gans of Warble-fly {Hypoderma 

 bovis). Te, testis; V.d., vas de- 

 ferens ; A.G., accessory glands; 

 £).e., ejaculatory duct; 5. e., ejacu- 

 latory sac ; 6, 9, 10, terga of the 

 sixth, ninth, and tenth abdominal 

 segments. X 8 

 and Hewitt. 



