446 MANUAL OF ELEMENTARY ZOOLOGY 



embryo of the rabbit a somewhat similar condition is found. 

 A strip of kidney tissue — the mesonephros — lying in front 

 of that which becomes the kidney of the adult, is served by 

 a Wolffian duct. In the adult male the mesonephros 

 becomes attached to the testis and the Wolffian duct 

 becomes the vas deferens. In the female these structures 

 are aborted. The adult kidneys of both sexes represent 

 only the metanephros or hinder part of the embryonic 

 kidney, which, instead of discharging through the Wolffian 

 duct, has a duct of its own, the ureter. From the con- 

 cavity or Atlus the ureter runs back to open into the 

 bladder. In the early stages of development this organ 

 joins the rectum in a cloaca, but later the latter becomes 

 divided, so that the urinary and generative organs discharge 

 by an independent passage through the vulva or the penis. 

 In front of each kidney lies a small, yellow, suprarenal 

 gland. The testes are a pair of ovoid bodies which arise 

 in the course of development on the dorsal wall of the 

 peritoneal cavity near the kidney, but later become free 

 and pass backward into two pouches of the body-wall at the 

 sides of the penis known as the scrotal sacs. Each testis 

 remains connected with its original position by a spermatic 

 cord, which consists of connective tissue with an artery 

 and vein. In passing backwards it carries with it the 

 mesonephros, which in the adult may be seen as the 

 epididymis, lying along the side of the testis and enlarged 

 at the front and hind ends into a caput and cauda 

 respectively. The cauda epididymis is connected to 

 the scrotal sac by a short, elastic cord known as the 

 gubernaculum. Each epididymis consists of a mass of 

 twisted tubules joining into a single, much-coiled tube 

 which becomes continuous at the cauda with the vas 

 deferens (or ductus deferens). This passes forwards out of 

 the scrotal sac, curves over the ureter, and passes backwards 

 again to open into a small median sac known as the uterus 

 masculinus, which lies above the neck of the bladder within 

 the pelvic girdle. The uterus masculinus opens into the 

 neck of the bladder, which is known after their junction as 

 the urinogenital canal or urethra, and passes backwards into 

 the penis, at the end of which it opens. Beside the uterus 

 masculinus lie the prostate glands which pass their secretion 



