336 DISSECTION OF THE BABBIT 



a separate opening to the exterior, through which the urinary 

 and genital products leave the body. 



It is convenient to describe the two sexes separately, as 

 they differ very greatly ; and to include in the account certain 

 glands in the neighbourhood of the rectum. 



A. The Male Babbit. 

 1. The renal system. 



a. The kidneys are a pair of dark red bodies about an 



inch and a quarter long, imbedded in fat in the 

 dorsal wall of the abdomen, outside the peri- 

 toneum. Each is of a flattened ovoid shape, with 

 a notch, the hilus, on its inner side where the 

 ureter and blood-vessels enter and leave it. 



Bisect one of the kidneys longitudinally, from its outer 

 edge; and turn the ventral half inwards, so as to expose the 

 cut surfaces. 



i. The cortical substance forms the superficial 

 layer of the kidney ; the Malpighian bodies, 

 which are confined to it, give it a dotted 

 appearance. 



ii. The medullary substance, forming the deeper 

 part of the kidney, is radially striated, and 

 consists mainly of the non-glandular parts of 

 the tubules. The inner surface of the medul- 

 lary substance is raised into a number of conical 

 papillag or pyramids, on which the tubules open. 



iii. The pelvis is the expanded anterior end of the 

 ureter, which lies in the cavity of the kidney, 

 and receives the urine from the apertures on 

 the pyramids. 



b. The ureters are a pair of slender tubes, running 



back from the kidneys along the dorsal wall of 

 the abdomen, a short distance from the middle 

 line. At the hinder end of the abdomen, they 

 turn inwards and open into the bladder, opposite 

 the anterior border of the pubic symphysis. 



