I 7 ELEMENTS OF MAMMALIAN ANATOMY. 



The mammary glands of the adult female cat reach 

 their full development when it gives birth to young. They 

 may be seen by carefully removing the skin from the ven- 

 tral aspect of the body, when they will appear somewhat 

 like a thin layer of adipose tissue extending from near the 

 axilla to the pubic symphysis. There are four teats or 

 nipples on each side. In some mammals the nipples are 

 less numerous and confined either to the thoracic or inguinal 

 region. In the elephant, Chiroptera, and Primates there 

 are but two nipples, and they are thoracic. In most 

 Ungulates' the nipples are inguinal. 



THE MALE REPRODUCTIVE SYSTEM. 



The organs of generation in the male consist of the 

 testes, the ducts leading from the testes to the urethra, the 

 prostate gland, Cowper's gland, and the penis. 



The testes are two in number, contained in a pouch of 

 integument called the scrotum, which hangs beneath the 

 anus. Internally the scrotum is divided into two chambers. 

 By dissecting away the adipose tissue covering the spermatic 

 cord in the inguinal region (Fig. 51) it may be seen that 

 the cord and the testes are enveloped by a tough sheath. 

 This is composed of cremasteric fascia derived from the 

 aponeurosis of the external oblique muscle, and of the tunica 

 vaginalis. 



During the fetal life the testes lie in the abdominal cavity, 

 and when they descend into the scrotum about the time of 

 birth, a double layer of peritoneum is pushed down before 

 them through the inguinal canal, forming a diverticulum 

 whose blind end lies within the scrotum, while the con- 

 stricted portion forms a channel for the vas deferens, 

 spermatic nerve, and vessels. These three structures form 

 the spermatic cord (Fig. 51). The fascia propria (tunica 

 vaginalis communis) is inseparably united with the adjacent 



