ANATOMY. 59 



The trachea is small, and anyone who has at- 

 tempted to inject gasoline into it will concur in 

 the statement that it is very mobile. 



The thoracic cavity is small, and the pleura 

 thick. 



The lungs are very unequal in size, the right 

 one being the larger. The left one has three lobes, 

 and the right has four or five. 



The thyroid is very extensive, being largely 

 utilized in the manufacture of a biological product. 



The thymus is very pale and delicate. 



THE URINARY ORGANS. 



The kidneys weigh about four ounces, and are 

 bean-shaped. The right kidney lies under the 

 first three lumbar vertebrae, while the left one 

 is usually further forward. In the adult sheep, 

 when the rumen becomes distended with food, the 

 left kidney is pushed back several inches. 



The ureter of the left kidney has a peculiar 

 course, due to the movable position of the kidney. 

 It curves upward and inward, and crossing the 

 median plane, runs backward on the left side. 

 The right ureter runs back in a relatively straight 

 line. 



The bladder is long and narrow, and extends 

 rather far forward on the abdominal floor. 



The adrenals are bean-shaped. The right one 

 lies along the inner border of the kidney and is 

 about an inch long and wide. The left one is 

 somewhat longer and slightly bent in shape. It 

 lies across the left renal vein, and is not in con- 

 tact with the kidney. 



