S62 MAMMALS. 



The kidneys are dark-red ovoid bodies lying on the dorsal 

 wall of the abdomen ; the one on the left is further down 

 than that on the right because of the position of the stomach 

 on the left side. When a kidney is dissected, a marked differ- 

 ence is seen between the superficial cortical part and the 

 deeper medullary substance. On papillae or pyramids in the 

 very centre, the coiled excretory tubules open, and empty 

 the water and waste-products which they contain into the 

 " pelvis " or mouth of the ureter. 



The ureters run backward along the dorsal wall of the 

 abdomen, and open into the bladder, a thin- walled sac lying 

 in front of the pelvic girdle. 



In front of each kidney lies a yellow adrenal body, of 

 unknown physiological significance. 



Reproductive Organs. — (a) Male. The testes arise on 

 the dorsal abdominal wall near the kidney, but as the rabbit 

 becomes sexually mature, they are loosened from their 

 original attachment, and pass out on the ventral surface, as 

 if by a kind of normal rupture, into the scrotal sacs. 



Each testis is moored to the base of the muscular scrotal 

 sac, and is bordered by a mass of convoluted tubes— the 

 epididymis, consisting of the caput epididymis anteriorly, 

 the larger cauda epididymis posteriorly, and a narrow band 

 between them. 



Through the tubes of the epididymis (the modified meso- 

 nephros), the spermatozoa developed in the testes are col- 

 lected into the vas deferens (the modified Wolffian duct), 

 which arises from the cauda epididymis, ascends to the 

 abdomen, extends round to the dorsal surface of the neck of 

 the bladder, and there opens beside its fellow into a median 

 sac called the uterus masculinus. In many Mammals paired 

 diverticula, known as seminal vesicles, are connected with 

 the ends of the vasa deferentia, but they are not developed 

 in the rabbit. 



The uterus masculinus is the homologue of the vagina in 

 the female, and seems to arise from the Miillerian ducts. It 

 opens into the urethra which runs backwards from the bladder, 

 and the urinogenital canal thus formed is continued through 

 the penis. 



Beside the uterus masculinus and the vasa deferentia, 

 there are lobed prostate glands opening by several ducts 



