INSECTA 



447 



Organs of reproduction (Fig. 313). In the male the testes are usually 

 small paired organs lying more or less freely in the body cavity. The 

 extent to which they are divided into follicles, and the form of follicle, 

 vary in different orders. Thus, in the Diptera, each testis is unifoUi- 

 cular, while in the Orthoptera a multifollicular condition prevails. 

 Each follicle is divided into Sigermarium or formative zone, a zone of 

 growth and maturation, and a zone in which spermatids are trans- 

 formed into spermatozoa. In multifollicular testes the connection 

 between each follicle and the main duct is known as the vas efferens 



Fig. 313. Diagram of reproductive organs of A, a male, and B, a female honey 

 bee. C, Longitudinal section of an ovariole of Dytisciis marginalis. A and B 

 after Comstock. ac.gl. accessory gland; be. bursa copulatrix; cgl. colleterial 

 gland; ed. ejaculatory duct;/, follicle cells; ge. germarium; ov. ovary; od. ovi- 

 duct ; o. ovum ; sc. spermatheca ; t. testis (multifollicular) ; vd. vas deferens ; 

 V. vagina; ve.se. seminal vesicles. 



and each testis leads to the median ejaculatory duct by a vas deferens 

 which is swollen at some point to form a seminal vesicle. The ejacu- 

 latory duct opens between the 9th and loth abdominal sterna in 

 association with the external genital plates (gonapophyses) of copu- 

 latory significance. Accessory glands of various kinds and little 

 understood function are usually found associated with the genital 

 ducts. 



The female organs (Fig. 313) consist of ovaries, oviducts, sperma- 

 thecae, colleterial glands and a bursa copulatrix. 



