THE BACTERIA OF THE HUMAN BODY 327 



bacteria. The dentine is next decalcified and softened. It 

 is an interesting observation that it takes longer for the bac- 

 teria to produce a complete change in the soft dentine than in 

 the hard enamel. Once the dentine is softened the bacteria 

 follow the tubules and enter the pulp cavity, destroying tissue 

 as they go. It is possible after this stage is reached for vari- 

 ous pathogenic microorganisms, such as the pus cocci, actino- 

 myces, etc., to effect an entrance through the carious por- 

 tions of the teeth and produce a generalized infection in the 

 body. 



Fischer refers to the fact that bacteria not unlike those oc- 

 curring in the mouths of people in this day were found in the 

 hollow teeth of some of the Egyptian mummies, and this goes 

 to show that bacteria have been inhabitants of this region of 

 the human body for centuries. 



Bacteria of the Stomach and Intestines. Since the mouth 

 contains such a large variety of bacteria it is to be expected 

 that some of these organisms will constantly pass down into 

 the stomach with food and drink. 



The bacteria find the healthy stomach an unfavorable place 

 for growth. The gastric juice in the normal stomach con- 

 tains a quantity of free hydrochloric acid (HC1). The ex- 

 periments of Strauss and Wurtz and others demonstrate the 

 fact that the normal gastric juice is decidedly germicidal. It 

 owes this property to the free hydrochloric acid it contains, 

 and not to any ferment. It has been repeatedly demonstrated 

 by different observers that |,he normal gastric juice is free from 



