CHAPTER VIII 
INTESTINAL BACTERIA 
Tue flora of the mouth is dependent upon many factors and is, 
therefore, continually changing. Excluding the various infections of 
the mouth which will not be considered here, the bacteria in the mouth 
are not especially significant. There are, however, several features 
which, compared with other body fluids, are worthy of mention. The 
mouth often contains a large number of bacteria and many kinds. 
Germicidal Action of Saliva. The work which is available on this 
subject is neither conclusive nor extensive. Huggenschmidt (1896) 
studied the various factors which contribute to the protection of the 
oral cavity and from such factors as bactericidal action of the sputum, 
mechanical action of the saliva, action of the mucous membrane and 
bacterial antagonism concluded that the mechanical action of the 
sputum was the most important factor. Sanarelli (1891) filtered saliva 
through a Chamberland filter and tested the bactericidal action of the 
filtrate. He found that saliva did possess a germicidal action quite 
similar to that exhibited by other body fluids, such as blood, aqueous 
humor, etc. The speed of the reaction depended upon the initial num- 
ber of bacteria introduced into the saliva. If a small number of cells 
(three or four hundred) were introduced, all were killed in a short time 
but when a few thousand cells were introduced, there was usually a 
decrease followed by an indefinite increase. With Bacterium diphtherice 
and the pneumococcus no germicidal action was noticed. They were 
found alive after twenty-eight and forty days. The cause of the ger- 
micidal action-was not determined. Gordon (1916) carried out his 
experiments on this subject in culture media and found a germicidal 
action against the meningococcus, which he attributed to the antagon- 
istic effect of other bacteria in the saliva. These were supposed to be 
mixed streptococci. 
Effects of Tobacco Smoke on Bacteria in the Mouth. This is a 
subject of more popular interest and has been of much use to those who 
wish to justify or decry the habit of smoking. Koerner (1896) found 
a decided reduction of bacteria in the mouth due to tobacco smoke. 
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