76 PATHOGENIC BACTERIA. 



men concerning the presence of the pyogenic cocci which 

 Miller rarely found in healthy mouths, and among which 

 Vignal failed to find the streptococcus in his extensive 

 researches. Block, on the other hand, found the strepto- 

 coccus three times and the staphylococcus four times in 

 the healthy human mouth. 



The small number of pathogens that flourish in the 

 mouth may depend upon an antiseptic action of the 

 saliva. Sanarelli endeavored to prove that such an action 

 existed, and found that when Staphylococcus pyogenes, 

 Streptococcus pyogenes, Micrococcus tetragenus, and the 

 typhoid and cholera germs were added in very small 

 amounts to filtered saliva, they did not grow, but in 

 twenty-four hours had died. If more plentiful inocula- 

 tions were made, enough of the germs survived to give 

 an abundant development. 



The stomach, in spite of the fact that it constantly re- 

 ceives myriads of bacteria from the ingested foods and 

 drinks, and is always receiving saliva containing bacteria, 

 is not a favorable environment for bacterial growth be- 

 cause of the acidity of its secretion. In health very few 

 bacteria live in the stomach, and in all probability a large 

 majority of those ingested die in the presence of the acid 

 secretions. The micro-organism most frequently observed 

 in gastric contents is a yellow sarcina, probably identical 

 with the Sarcina ventriculi of the older writers. It is not 

 known to have any pathogenic powers, though such have 

 been attributed to it, because in all cases in which the 

 gastric secretions are disturbed and alkalinity or exces- 

 sive acidity is present this sarcina is observed in increased 

 numbers. 



In the diseased stomach the bacteria vary according to 

 the existing conditions. Thus, if the secretions be alka- 

 line, any of the bacteria that happen to be swallowed may 

 thrive and the gastric flora become quite extensive. The 

 most frequent bacteria observed in disease-conditions are 

 those of lactic and butyric acid fermentation. 



The Oppler-Boas has attained to some reputation as an 



