660 BACTERIA OF THE STOMACH AND INTESTINE. 
into glucose, etc., was found to be so long that there was no reason 
to suppose that any one of the microérganisms tested was con- 
cerned in ordinary stomach digestion. 
In the zntestine conditions are favorable for the development of 
many species of saprophytic bacteria, and the smallest quantity of 
excrementitious material from the bowels, spread upon a glass slide 
and stained with one of the aniline colors, will be found to contain 
a multitude of microédrganisms of this class, of various forms. 
Among these are certain species which have their normal habitat in 
the intestine, and which may always be obtained in cultures from 
this source, while others, having been present in food or water in- 
gested, and having escaped destruction in the acid juices of the 
stomach, are accidentally and temporarily present. These latter 
may or may not increase in the organic pabulum which abounds in 
the intestine, according as the conditions are favorable or otherwise. 
The strictly aérobic bacteria could not multiply because of the ab- 
sence of oxygen, and the species encountered are for the most part 
anaérobics or facultative anaérobics. The Bacillus coli communis 
of Escherich, which is the most constant and abundant species found 
in the intestine of man and of certain of the lower animals, is a facul- 
tative anaérobic, which grows readily in the ordinary culture media, 
either in the presence of oxygen or in an atmosphere of hydrogen. 
But certain other bacteria of the intestine are strictly anaérobic and 
do not grow readily in the media commonly employed by bacteri- 
ologists. 
Escherich has shown that in new-born infants the meconium is 
free from bacteria. At the end of twelve to eighteen hours after 
birth bacteria appear in the alvine discharges, and the number is 
already considerable at the expiration of the first twenty-four hours 
of independent existence. The species first found are cocci and yeast 
cells which no doubt come from the atmosphere, having been de- 
posited upon the moist mucous membrane of the mouth and swal- 
lowed with the buccal secretions. When the meconium is replaced 
by “‘milk feeces” these contain in large numbers the Bacillus coli 
communis, heretofore spoken of as the most common species found in 
the intestine of adults. Another species associated with this, but 
not so abundant, is the Bacillus lactis aérogenes of Escherich. 
Other bacilli and cocci are found occasionally in smaller numbers. 
These bacilli do not liquefy gelatin, and, as a rule, the microér- 
ganisms found in the alvine discharges of healthy persons are non- 
liquefying bacteria. Escherich’s researches led him to the conclu- 
sion that the Bacillus lactis aérogenes is constantly present in the 
small intestine of milk-fed children as the most prominent species, 
and that its multiplication there is favored by the presence of milk 
