126 INFECTIONS OF THE DIGESTIVE TRACT 



fermentation tubes was inoculated in a uniform manner. 

 The fermentation tubes contained dextrose bouillon, 

 levulose bouillon (made with Schering's diabetin), lactose 

 bouillon, saccharose bouillon, peptone bouillon and plain 

 bouillon, litmus milk, dextrose bouillon containing methyl- 

 ene blue, dextrose bouillon containing neutral red, and 

 dextrose bouillon containing methyl violet. The tubes 

 containing the dyes were employed to determine the 

 reducing activity of the bacteria. As the information 

 yielded by these color tubes did not appear especially 

 helpful, the method was temporarily abandoned. Far 

 more useful was the study of the gas production in the 

 sugar-bouillon tubes. These tubes contained concen- 

 trations of the sugars already mentioned equal to two 

 per cent, in each case. It was found that the least 

 gas was usually obtained on the saccharose medium, 

 and the most on the dextrose or lactose. The quantity 

 of gas produced in conditions of health by the mixed 

 flora is somewhat variable, but may be roughly stated 

 as varying ordinarily from fifteen to thirty per cent, 

 of the height of the anaerobic limb. This estimate is 

 based not on any one sugar tube, but on the average of 

 the four tubes, the gas production, as already stated, 

 having been unequal in these different tubes. In normal 

 children on a milk diet the gas production is often some- 

 what less than in adults and may be not more than ten 

 to fifteen per cent. In conditions of disease the gas 

 production was found to be usually considerably less 

 than the average production in health. This is true 

 both of adults and of children. In the case of well- 



