74 



APPLIED PHYSIOLOGY 



germs into the skin. They seldom grow in the blood, for 

 it is in too rapid motion, but they do grow in the lymph 

 and produce millions of new bacteria. They may fall upon 

 a sore spot, or a cut, and so go into the lymph at once. 

 These bacteria live upon the lymph and give out poisons 

 which may make the whole body sick. Typhoid fever, 

 diphtheria, cholera, and erysipelas are kinds of sickness 

 caused by the bacteria. When a cut discharges matter, 

 it is due to the same thing. The growth of these germs, 

 and the effect of the poisons which they make, is what is 

 usually meant by "taking cold." 



Bacteria are always ready to enter the lymph, and the 

 object of the physician and surgeon is to keep them out. 



^ _____ . When the germs are 



a 



kept out, heat and cold 

 and wet will not make 

 a person take cold in a 

 cut or wound of any 

 kind. 



137. Inflammation. 

 Whenever the body is 

 hurt, the first thing it 

 does towards mending 

 the wound is to loosen 

 the muscles of the arte- 

 ries going to the hurt 

 spot, so as to let more 

 blood go there. This makes the part red. Then the 

 white blood cells begin to stick to the sides of the finest 

 blood tubes and to pass through their sides into the 

 lymph spaces. At the same time more of the watery parts 

 of the blood leave the capillaries. This makes a sivelling, 

 while the pressure of the swelling upon the nerves gives 





Beginning of inflammation (x 400). 



a white blood cells adhering to the wall of a 

 capillary and passing through it. 



b white blood cells which have passed out- 

 side of the capillary in order to repair an 

 injury. 



c white blood cells passing through the capil- 

 lary. 



d wall of capillary. 



