COCKROACH. 



315 



REPRODUCTIVE SYSTEM. 



OF THE MALE. 



OF THE FEMALE. 



The testes are paired organs, sur- 

 rounded by the fatty body 

 below the 5th and 6th ab- 

 dominal terga. They atrophy 

 in the adult. 



From the testes, two narrow ducts 

 or vasa deferentia lead to two 

 seminal vesicles. 



These seminal vesicles (the ' ' mush- 

 room-shaped gland") open into 

 the top of the ejaculatory duct. 



This duct opens between the 9th 

 and loth sterna. Beside the 

 aperture, there are copulatory 

 structures (gonapophyses). 

 With the ejaculatory duct a 

 gland is associated. 



The ovaries are paired organs, in 

 the posterior abdominal region , 

 each consisting of eight ovarian 

 tubes. These are bead-like 

 strings of ova at various stages 

 of ripeness. 



From the ovarian tubes of each 

 side eight eggs pass at a time 

 into a short wide oviduct. 



The two oviducts unite and open 

 in a median aperture on the 

 8th abdominal sternum. Be- 

 side the aperture are hard 

 structures (gonapophyses) 

 which help in the egg-laying. 

 Here also a pair of " col- 

 leterial " glands pour out their 

 cementing secretion by two 

 apertures. The spermatheca 

 is a paired sac with a single 

 aperture on the gth abdominal 

 sternum. 



Sixteen ova, one from each ovarian tube, are usually 

 enclosed within each egg-capsule. The latter is formed 

 from the secretion of the colleterial glands. Each egg is 

 enclosed in an oval shell, in which there are several little 

 holes (micropyles), through one of which a spermatozoon 

 enters. Spermatozoa, from the store within the spermatheca, 

 are included in the egg-capsule. The development is 

 similar to that of other insects, and it has already been 

 mentioned that there is no metamorphosis. 



At an early stage in development some cells associated with the 

 mesoderm are set apart as reproductive cells, and originally these have 

 a segmental arrangement as in Annelids ; at a later stage other meso- 

 derm cells join these, some forming ova, others epithelial cells around the 

 latter. The distinction between truly reproductive cells and associated 

 epithelial cells, which is said to be late of appearing in some of the 

 higher insects, is established at a very early stage in the cockroach. 



