KIDNEYS. 



421 



vidual to apply to his own case. Bathing, except a sponge- or 

 plunge-bath, should not be practised when the vital powers are low, 

 as early in the morning, nor after a long fast, nor should it be 

 indulged in too soon after eating ; eleven o'clock in the morning 

 is, for the average person, a proper time for a bath of considerable 

 duration. 



THE URINARY APPARATUS. 



The kidneys (Fig. 238) are situated in the lumbar region of 

 the abdominal cavity, one on each side of the spinal column, with 

 the upper border on a level with the twelfth dorsal, and the 



FIG. 238. Longitudinal section through the kidney : 1, cortex ; 1', medullary 

 rays; 1", labyrinth; 2, medulla; 2', papillary portion of medulla; 2", boundary 

 layer of medulla ; 3, transverse section of tubules in the boundary layer ; 4, fat of 

 renal sinus ; 5, artery ; *, transverse medullary rays ; A, branch of renal artery ; C, 

 renal calyx ; U, ureter (after Tyson and Henle). 



lower opposite the third lumbar vertebra. The dimensions of each 

 are approximately : Length, 10 cm. ; breadth, 5 cm. ; thickness, 

 2.5 cm. The weight is from 125 to 180 grams. 



The shape of the kidney is like that of a bean, the internal 



