220 VERTEBRATE ZOOLOGY 



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 layer, 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. 

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

 which, as we have already learned, is called the pelvis. The open- 

 ing of the sinus to the outside, through which the ureter emerges, 

 is the hilus. 

 Exercise 13. Make a drawing of the cut surface of the kidney. 



The suprarenal, or adrenal, bodies are a pair of ovoid bodies 

 which lie embedded in fat immediately in front of the kidneys. 



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

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

 called the scrotal sac, 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 bilobed prostate gland and the paired 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 enters the neck of the bladder. Follow one of them to 

 the bladder. Follow it in the opposite direction ; it may be traced 

 back to the muscular wall of the abdominal cavity, through which 

 it passes by a small opening called the inguinal canal, and finally 

 enters the spermatic cord and proceeds to the testis. Carefully 

 remove the skin from the scrotal sac, and from the penis, which 

 lies between the testes. 



The scrotal sac will be seen to contain two compartments, in 

 each of which lies a testis. Expose one of the testes. It is a 

 compact elliptical body composed of a mass of tubules, which may 

 be seen through the outer covering; these are the seminiferous 



