QUESTIONS AND ANSWERS 89 



not open but is thick and solid there as elsewhere. A case of unilat- 

 eral pleurisy in the horse tends to become bilateral because the 

 effusion, and hence the infection, can readily pass from one side to 

 the other. In cattle, localization of the disease in one side is 

 possible. 



Urinary Organs 

 Describe the kidney. 



The kidneys, two in number, are situated in the right and left 

 sublumbar region, against the psoas muscles, usually imbedded in 

 fat, and supported beneath by the peritoneum. The right kidney 

 is heart-shaped and more anterior than the left, which is bean- 

 shaped. Each kidney has a superior and inferior flattened surface, 

 an external convex border and an internal concave one which is 

 deeply notched, the hilimi. In the hilum, the blood-vessels, nerves 

 and beginning of the ureter are lodged. Inside, at the hilum, is a 

 cavity, the pelvis, into which the uriniferous tubules empty and 

 which is the beginning of the ureter. 



The kidney is encapsulated by a fibrous coat which sends pro- 

 longations into its substance. The tissue proper of the kidney is 

 divided into an external or cortical layer and an internal or medul- 

 lary layer. The cortical layer contains the malpighian corpuscles 

 and the medullary layer contains the uriniferous tubules. 



Blood supply: renal artery. 



Nerve supply : branches from the solar plexus. 



Function : secretion of urine. 



Compare the kidney of the horse with that of the ox. 



In the ox, the kidneys are more elongated from before to behind, 

 and are divided into 15 to 20 lobules, the structures of which are 

 comported like so many separate kidneys. 



Describe the ureters. 



The ureters, two in number, are membranous canals, beginning 

 at the pelvis of the kidney and running backward and downward to 

 the upper face of the bladder, which they enter in an oblique direc- 

 tion. Size, about l^ inch in diameter. Structure consists of an 

 external fibrous coat, a middle muscular and an internal mucous. 



Function : to convey urine from the kidneys to the bladder. 



Describe the urinary bladder. 



The bladder is a musctilar bag, situated in the inferior part of 

 the pelvic cavity, and has three openings, viz., the openings of the 

 two ureters and the beginning of the urethra. Its structure is 



