60 RELATION OF BACTERIA TO DISEASE 



delicacy of the latter renders infection through them quite 

 easy. They may go in through the intestinal tract and be 

 absorbed by its wall. They may go in through the tonsils, 

 larynx, or trachea. In exposure to cold with the congestion 

 and sensitiveness of the larynx produced thereby we have an 

 opportunity for the absorption of bacteria. Not all bacteria 

 can enter by all ways and produce disease. The pus cocci, if 

 swallowed, are destroyed by the gastric juice, while typhoid 

 bacilli usually pass the stomach uninjured. Typhoid bacilli 

 rubbed into the skin would be followed by no disease, but pus 

 cocci so applied would cause boils. Most of the secretions 

 and excretions, except, of course, the feces, may be said to be 

 mildly inhibit! ve to bacterial growth. The defences of the 

 body to a local introduction of bacteria depend upon the 

 healthiness of the skin and mucous membranes. The resist- 

 ance offered has been found to be due to a power supplied by 

 the blood serum This is .discussed later. Any physical 

 condition such as a burn or wound reducing the healthy 

 trim of the body renders invasion easier. Injury and intoxi- 

 cation materially favor the activity of bacteria either pre- 

 viously within the individual or introduced at the time. 

 Normal bodily resistance is impaired by excessive hunger 

 and thirst, by exposure to cold and wet, or by prolonged 

 muscular or mental strains. 



Conditions resulting after the entrance of bacteria into the 

 body may be defined as follows: Infection is best considered 

 as the presence of disease- producing germs and the evidence 

 of their effects. Intoxication is the condition due to the 

 poisons elaborated by bacteria. Bacteremia is the mere 

 presence of bacteria in the blood while septicemia is the circu- 

 lation of bacteria and their products in the blood, with some 

 involvement of all the organs in the body. Pyemia is similar 

 to the last but includes the production of many abscesses 

 throughout the body. Fever may be described as a disturb- 

 ance by bacterial poisons of the mechanism in the brain 

 which controls the heat of the body. 



