INFECTIONS. 1 1 



of body tissues. The more common general reactions are fever, 

 digestive disturbances, effects on the nervous system, leucocytosis, 

 anaemia, and enlargement of the spleen and oilier glands. 



Infections and infectious diseases may be divided into two 

 classes; one in which the disease runs a self-limited course, recovery 

 coming after a definite period of time has elapsed, while in the 

 other class the course may be extended over a very indefinite 

 period of time. 



The elimination of the casual or etiological factor of infections 

 and infectious diseases occurs in various ways. When the seat 

 of the disease is on the surface of the body, the organisms are elim- 

 inated with the diseased tissues, but when the organisms are 

 found in parts of the body where this is impossible, the microor- 

 ganisms must enter the general circulation, be allowed to pass 

 through the glandular tissues and be eliminated with the secretions 

 and excretions. In the blood and the body tissues, bacteria 

 are in many cases destroyed by bacteriolytic and bactericidal sub- 

 stances. Sometimes after an apparent recovery from the disease, 

 viable organisms may remain and at a later time again give rise 

 to disease. 



