the foods in the digestive tract. Sherman holds
that there are three main types having this property: "(1) the
bacteria of fermentation, such, for example, as the lactic acid
bacteria; (2) the putrefactive bacteria, such as the anaerobic B.
aerogenes capsulatus; (3) bacteria of the B. coli type, showing the
character of both the fermentative and putrefactive organisms but
tending in general to antagonize the putrefactive anaerobes."[57]

~Fermentation in the Stomach.~--In the stomach, fermentation of the
carbohydrates with the production of organic acids, and at times
alcohol, occurs. The types of fermentation taking place in the stomach
are alcoholic, lactic, butyric, acetic, formic, oxalic, and cellulose.
The bacteria inhabiting the gastric organs are dependent upon air for
existence, while those in the intestines are not.

~Factors Influencing Excessive Fermentation.~--The factors influencing
excessive fermentation in the stomach are lack of "tone" and motility
in the organ, insufficient amount or absence of free hydrochloric acid
in the gastric secretion, dilatation of the stomach, and an excess of
carbohydrate foods in the diet. Of the latter, sucrose and glucose are
especially susceptible to the action of fermentative bacteria. Under
normal conditions, that is, in health, the conditions prevailing in
the stomach are very unfavorable to the development of bacteria of the
putrefactive type, the gastric juice exhibiting decided germicidal
properties. Then, too, the presence of air acts against their
development. Much of the so-called gastric fermentation does not occur
in the stomach but rather in the duodenum.

~Bacterial Action in the Intestines.~--In the lower part of the small
and in the large intestines, the bacteria of the anaerobic type
increase, conditions more favorable to their development existing
there than farther up in the intestinal tract. However, there are a
great many bacteria in the whole of the small intestine. Those
producing decomposition of the unabsorbed proteins are especially
prominent in the colon.

Herter[58] states that "the presence in the colon of immense numbers
of obligate micro-organisms of the B. coli type may be an important
defense of the organism in the sense that they hinder the development
of that putrefactive decomposition which, if prolonged, is so
injurious to the organism as a whole. We have in this adaptation the
most rational explanation of the meaning of the myriads