PLACENTAE MAMMALIA. 



831 



viscera of the male Hedgehog. The rectum (a) and the neck of the 

 bladder (&) remain in situ ; but the rest of the latter viscus has been 

 removed, and the first portion of the urethra (e) slit open, in order to 

 show the relations of the surrounding parts. 



(2458.) The testes (b 6) present the same structure in all the class, 

 and consist essentially of an immense assemblage of extremely delicate 

 tubuli seminiferi enclosed in a dense albugineous tunic, from which 

 septa pass internally, whereby the seminiferous tubes are divided into 

 several fasciculi : after 

 piercing the proper 

 fibrous tunic of the 

 testes, the sperm-se- 

 creting tubes are col- 

 lected into an ex- 

 tremely tortuous duct, 

 that by its convolu- 

 tions forms the epi- 

 didymis, as in Man, 

 and is then continued, 

 under the name of vas 

 defer ens, to the com- 

 mencement of the ure- 

 thra, into which the 

 two ducts open (B, b b). 

 In the Horse, and 

 many Ruminants, the 

 vas deferens presents 

 a remarkable struc- 

 ture : before its ter- 

 mination it suddenly 

 swells to a consider- 

 able diameter, de- 

 pending upon the increased thickness of the walls of the canal, which at 

 the same time become cellular, and secrete a gelatinous fluid that escapes 

 into the cavity of the duct. 



(2459.) In their situation the testes of placental Mammals are found 

 to offer very striking differences. In the Cetacea, the Elephant, and 

 the Seal, they remain permanently in the abdomen, bound down by a 

 process of the peritoneum. In Man, and most quadrupeds, on the con- 

 trary, they pass out of the abdominal cavity through the inguinal rings, 

 and are suspended in a scrotal pouch formed by the skin, and a cre- 

 master muscle, and lined by a serous prolongation of the peritoneal sac. 

 The spermatic cords, therefore, formed by the vessels and excretory 

 canal of the testes, will take a different course, in conformity with the 

 variable position of these organs, and, where a scrotum exists, must 



Male generative apparatus of the Hedgehog. 



