XII 



THE SKIN AND THE KIDNEYS 



161 



they take heat from the body and hence lower its tem- 

 perature very fast. All garments worn at night, as 

 well as the bedclothes, should be thoroughly aired and 

 sunned every morning so as to keep them perfectly dry 

 and free from disease germs. 



120. The Kidneys. The kidneys are bean-shaped 

 organs, about four inches long and two inches wide, 

 located in the back part 

 of the abdomen, just be- 

 low the last rib, one on 

 either side of the back- 

 bone. They are covered 

 with a capsule of fat. In 

 appearance the kidneys in 

 man are quite like those 

 of the sheep. There are 

 two quite distinct layers 

 in the kidneys, the cortex 

 on the outside and the 

 medulla on the inside. In 

 structure, the kidney re- 

 sembles the skin in many 

 ways. If you can imag- 

 ine a small piece of skin 

 turned inside out, with the 

 two layers thickened considerably and folded up in the 

 shape of a bean, you have some idea of the real 

 structure of the kidney. Like the skin they contain 

 glands in the cortex, and many long, fine tubules wind- 

 ing back and forth in the cortex and medulla. These 



FlG. 82. A longitudinal section of the 

 kidneys (Huxley) : Cf, cortex; m, me- 

 dulla; Py, pyramid in the medulla; 

 P. pelvis; U, ureters; RA, renal 

 artery. 



