THE BACTERIA OF THE HUMAN BODY 329 



although digestion of fibrin and conversion of starch into 

 dextrose did take place as a result of bacterial action, the 

 time required for such reactions was so long that there 

 was no basis for assuming that any of the bacteria were 

 concerned in the process of digestion in the normal stomach. 



In the intestine a large variety and an immense number 

 of bacteria are constantly present. Some of these bacteria 

 are present in the intestine constantly, while others occur 

 only occasionally. The intestinal contents being alkaline in 

 reaction and the temperature constant and relatively high, 

 most of the bacteria present find optimum conditions. A 

 great many of the bacteria found in the intestine are the 

 saprogenic or putrefactive organisms. The species of bac- 

 teria encountered in the intestine are for the most part 

 anaerobes or facultative anaerobes. The strict aerobic 

 bacteria are not capable of multiplying to any great extent 

 in the intestine on account of the scarcity of oxygen. On 

 the inside of the intestine, in contact with mucous membrane, 

 aerobic changes may take place to a limited extent. B. coli 

 is one of the many microorganisms which is facultatively 

 anaerobic and a natural inhabitant of the intestinal tract. 



The end-products of the zymogenic and saprogenic processes 

 which take place in the intestine vary with the character of 

 the food in the intestine on which the bacteria are acting. If 

 protein material similar to meat is acted upon, the process is 

 essentially saprogenic, and the end-products produced include 

 amino acids, aromatics, and gases, such as leucin, tyrosin, 



