670 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 microorganisms tested was con- 

 cerned in ordinary stomach digestion. 



In the intestine 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 microorganisms 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 aerobic bacteria could not multiply because of the ab- 

 sence of oxygen, and the species encountered are for the most part 

 anaerobics or facultative anaerobics. 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 anaerobic, 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 anaerobic 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 faeces " 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 aerogenes of Escherich. 

 ( )ther bacilli and cocci are found occasionally in smaller numbers. 

 These bacilli do not liquefy gelatin, and, as a rule, the microor- 

 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 aerogenes 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 



