THE BACTERIA OF THE ALIMENTARY TRACT. 171 



testinal putrefaction, its qualitative and quantitative deter- 

 mination, its physiological and pathological importance, and 

 the means of combating it. Of the nature of these decompo- 

 sitions we know as yet but little. That they are enzymatic 

 in character is proven by numerous experiments and is gen- 

 erally conceded, but of the nature of the individual enzymes 

 which are active we are almost entirely ignorant, as also of 

 the finer chemistry of the changes which occur in the alimen- 

 tary contents in their transformation into the substances 

 which we recognize as the products of bacterial activity. 



When the alimentary contents are analyzed chemically it 

 is found that a fairly distinct division can be made between 

 the nature of the substances found above, and those dis- 

 covered below the ileocsecal valve. The bacterial decom- 

 position products found in the stomach may be dismissed 

 with the statement that under normal conditions none 

 are found. This is dependent upon a number of facts: 

 first of all the high acidity of the gastric juice which lies 

 far above the limits inside of which most fermentative 

 changes can take place, and secondly, the short time (at 

 most a few hours) that the food remains in this viscus. What- 

 ever bacterial decompositions are possible in the stomach 

 can, therefore, never reach a high grade in the limited time 

 allowed for such changes under normal circumstances. The 

 physiological importance of these two circumstances mani- 

 fests itself most clearly when through experiment or disease 

 they are missing. Every day clinical observation suffices to 

 show how the stomach contents of a patient whose gastric 

 juice contains too little acid, or whose stomach does not 

 empty itself except after long intervals, are teeming with 

 bacteria and the products of their enzymatic activities. 

 These products differ and fall into the group of those derived 

 from the fats, carbohydrates, or proteins of the ingested food 

 according to the conditions found in the stomach as deter- 

 mined by the changes in the viscus itself, the food, and the 

 character of the bacteria present. 



