BLEEDING, WOUNDS, AND DISEASE GERMS 75 



pain. The three signs, namely, redness, swelling, and pain, 

 generally mean that a part is inflamed. 



138. Repair of wounds. The object of the increased 

 quantity and action of the blood is to heal the injured part. 

 If some of the cells of a part have been killed by an injury, 

 the white blood cells eat up the dead parts and carry them 

 off with the lymph. Some of the white blood cells become 

 branched, and fit themselves into the spaces between the 

 cells, and so become a part of the flesh. Thus the cut or 

 injured parts are mended. The new flesh does not look 

 like the old, but is puckered and firmer. It is called a 

 scar. 



139. Taking cold. Now suppose bacteria are doing 

 damage to the body, or get into the lymph spaces after it 

 is done. Then they multiply and produce poisons which 

 harm the body far more than the first injury. The white 

 blood cells fight these bacteria. Whole armies of cells 

 rush to the spot and usually soon overcome the germs. 

 But many times the white blood cells are killed in the 

 fight. Then others rush in, until they pack the lymph 

 spaces tightly and fill the ends of the blood tubes and so 

 cut off the supply of food. So the bacteria are besieged 

 until they are starved to death, but the cells of the body 

 also starve. Finally the germs, the white blood cells, and 

 the cells of the body all die and soften and run out as 

 matter, or pus. This is called a gathering, or abscess. A 

 boil is an example of this. ' After the matter has run out, 

 the white cells grow over the bottom and sides of the hole 

 and soon mend it with a scar. So a few of the cells of the 

 body give their lives in order that the rest may be saved. 

 Those that were killed and formed the foul matter were 

 just as good and strong cells as those that were left and 

 healed the wound. They were not impurities in the blood, 



