BACTERIA OF THE COLON TYPE IN HUMAN INTESTINES 251 

 SUMMARY 



A collection of 177 cultures of the colon-aerogenes type was 

 made from human feces. 



These were examined for pigment formation, indol production, 

 liquefaction of gelatin, the acid fermentation of glucose, lactose, 

 sucrose, raffinose, melibiose, arabinose, inulin, mannitol, dulcitol, 

 adonitol, and glycerol, the methyl red test, the carbinol or 

 Voges-Proskauer reaction and the anaerobic production of gas 

 from glucose as determined by exact methods. 



Of the 177 cultures studied, 131 gave a CO^/Ho ratio of approx- 

 imately 1.06. The remaining 46 cultures gave ratios varying 

 from 1.5 to 2.7. 



The methyl red tests correlated perfectly with the gas ratios. 



None of these cultures fermented inulin but practically all 

 fermented mannitol and glycerol. Nearly all of the low ratio 

 cultures formed indol but all were negative to the carbinol reac- 

 action. A relatively small percentage fermented sucrose, raffi- 

 nose, dulcitol and adonitol. 



The high ratio cultures included a small percentage of indol 

 producers but all gave a positive carbinol reaction. All of them 

 fermented sucrose, raffinose, and adonitol. Only a small number 

 fermented dulcitol. 



The high ratio group agreed very closely with a group repre- 

 sented by a small number of cultures isolated from grains and 

 described in an earlier paper. The greater number of the grain 

 cultures differed from the fecal cultures in their ability to ferment 

 alcohols, particularly adonitol. 



A tentative scheme of classification for the typhoid colon 

 group is presented in which the primary divisions are based on the 

 nature of the metabolism as indicated by the gases evolved. 



The gas analysis of a few available cultures of the paratyphoid 

 group gave a gas volume and ratio agreeing with that of the 

 colon type. 



REFERENCES 



Ateks and Johnson 1915 A bacteriological study of retail ice cream. U. S. 

 Dept- of Agric. Bull. 303. 



