THE RABBIT 283 



the neck of the bladder opens into the urogenital sinus, or vesti- 

 bule, a short wide space which receives also the vagina and is 

 equivalent to the urogenital canal of the male; it opens to the 

 outside through the vulva. Note the mesenteries which join the 

 bladder with the ventral and dorsal abdominal walls. 



Exercise 9. Draw a semidiagrammatic sketch of the urinary system. 



Remove one of the kidneys from the body, split it longitudi- 

 nally, and study the cut surface. The kidney will be seen to be 

 made up of a light-colored, peripheral portion, which is called the 

 cortical substance, and a darker, central mass, called the medullary 

 substance. The kidney tubules will be seen as fine lines which 

 converge to a large space near the concave side called the sinus ; 

 this contains the wide, funnel-shaped anterior end of the ureter, 

 which, as we have already learned, is called the pelvis ; the opening 

 of the sinus through which the ureter emerges is the hilus. 



Exercise 10. Make a drawing of the cut surface of the kidney. 



Note the suprarenal glands, which are a pair of yellowish ovoid 

 bodies lying, often embedded in fat, near the medial side of the 

 anterior portion of the kidneys ; each is about half an inch long. 



The genital organs in the male are the following : a pair of geni- 

 tal glands called the testes, which lie in an integumental pouch, 

 called the scrotum, situated just ventral to the anus; a pair of 

 efferent canals, through which the spermatozoa are conducted 

 away from the testes to the urogenital canal ; two sets of glands, 

 the prostate gland and Cowper's glands, which furnish the fluid in 

 which the spermatozoa are suspended ; and ' the penis, through 

 which the urogenital canal, or urethra, passes to the external 

 opening at its distal end. 



Each efferent canal is made up of two portions, the epididymis 

 and the vas deferens. The vasa deferentia have already been seen ; 

 each appears as a long white cord which forms a loop around the 

 ureter and lies along the dorsal surface of the neck of the bladder, 

 finally terminating in the seminal vesicle. This is a large flattened 

 sac, slightly bilobed at its anterior end, lying between the rectum 

 and the neck of the bladder, with which it communicates at its 



