Ovaries 



animals, the union of two dissimilar 

 cells — a small active (male) sperm- 

 cell {spermatozooti) with a large, 

 passive (female) egg-cell {ovum) — • 

 is necessary for the development of 

 a new individual ; that is to say, 

 reproduction is sexual. 



Ovaries, &c. — The egg-cells 

 are formed in the ovaries of the 

 female. In the Cockroach there is 

 a pair of ovaries (fig. 49) situated 

 towards the hinder end of the 

 abdomen. Each ovary consists of 

 eight ovarian tubes, four above 

 and four below. At their forward 

 ends the tubes of each ovary are 

 exceedingly narrow, and unite into 

 a slender, solid thread, which is 

 attached to the fat-body. In its 

 hinder region each tube swells into 

 a tapering oval form and is often 

 beaded in appearance on account of 

 the eggs which it contains. The 

 eight tubes of each ovary open into 

 an oviduct, and the two oviducts 

 unite centrally to form a short pas- 

 sage (vagina) which opens to the 

 outside through a special sclerite 

 situated between the seventh and 

 eiglith sternites of the abdomen 

 (fig._52)(i, 51). 



Microscopical examination shows 

 that the wall of an ovarian tube 

 consists of a transparent elastic 

 membrane with cellular lining. In 

 the upper, narrow portion of the 



^'^'IU>*«»'"* 



Fig. 50. — Ovarian tube 

 of Cockroach, with 

 scattered nuclei (upper 

 figure) which form 

 follicles round the eggs 

 (lower figure). Highly 

 magnified. Fro'mMiall 

 &Denny(after Brandt). 



