STRUCTURE, GROWTH AND ECONOMICS OF INSECTS 29 



domen— never in the last. In most insects there is in the female a 

 seminal receptacle, a dorsal pouch of the vagina, and in the male a 

 seminal vesicle, a dilated portion of the vas deferens. The ova are 

 formed in the ovarian tubes in different stages of growth, the largest 

 and oldest being nearest the oviduct. The spermatozoa arise in the 



-susp. 



-5usp. 



ov. 



ubr 



-~ed. 



sp.c. 

 -int. 



Fig. 32. Fig. 33. 



Fig. 32. — Male reproductive organs of Gryllus pennsylvanicus. T., Testis; Susp., 

 suspensorium of testis; vd., vas deferens; ubr., u.maj., accessory glands on surface 

 of seminal vesicle; ed., ejaculatory duct; sp.c, spermatophore cup; int., intromittent 

 organ or penis. 



Fig. 33. — Female reproductive organs of Gryllus pennsylvanicus. Susp., Sus- 

 pensorium of ovaries; O., ovaries; ov., ovarian eggs; od., oviduct; C cercus; r.s., 

 seminal receptacle; d., duct of seminal receptacle; vag., vagina; be, copulatory 

 pouch; Ovp., ovipositor. 



follicles of the testes. There are also usually accessory glands which 

 secrete mucus that envelopes the spermatozoa and ova (Figs. 32 and 



33)- 



Parthenogenesis, or reproduction without fertilization, occurs in 

 many insects — in aphids, Cynips, Lasius (Ant), and some Coccids. 



