REPAIR OF INJURIES 



401 



of the flesh. Then the membrane will be red and tender 

 and possibly swollen. Owing to the thinness of the mem- 

 brane and of its epithelium, the plasma and white blood 

 cells will come to the surface. The matter may collect 

 until it is coughed up and expelled. The nose and throat 

 are the most often affected, but in severe cases it extends 

 to the trachea and lungs. When the matter fills the air 

 sacs of a part of the lung, the disease is called pneumonia. 



59 



The third stage of inflammation, or the formation of an abscess (X 50). 



a epithelium of the skin softened and bursting. 



b white blood cells which have packed the tissues full and shut out nourishment 



c blood tube stopped by white blood cells. 



In order to take cold there must be an injury to the cells, and 

 bacteria must grow upon the injured spot. It often happens that the 

 cells are exposed to injury, and no cold is contracted, for germs do 

 not happen to grow, while on the other hand the exposure may be 

 slight, and yet may enable germs to produce severe cold. 



In colds and in an abscess, the pus and discharged substances are 

 not foul matters which have been circulating in the blood, but consist 

 of the strong blood cells which have died fighting for the defense of the 

 body, and of plasma, which is an efficient protection against the germs. 

 Both being dead and charged with the toxins of the bacteria, they are 

 no longer of use, but should be expelled from the body. 

 ov. PHYSIOL. 26 



