106 TRANSFORMATION OF THE INTESTINAL FLORA 



CHART 42A 



Curves indicating percentage of B. bulgaricus appearing in fecal specimens from 



human subjects. 



Diet 



Ordinary daily diet 



B. bulgaricus 300 c.c. 



(Whey broth culture Neph. 5.) 



Ordinates — Per cent of B. bidgaricus. 



Abscissae — Number of days after administration of diet. 



INCOMPLETE ABSORPTION OF LACTOSE FROM THE 



INTESTINE 



In the feeding experiments with rats a direct correlation was estab- 

 lished between the transforming influence of lactose and dextrin on 

 the intestinal flora and the presence of a reducing substance in the 

 large intestine and in the feces. It was assumed, therefore, that these 

 carbohydrates owed their Bacillus acidop}iilus-?,imm[3iimg influence to 

 their incomplete absorption from the enteric tract. This view was 

 strengthened by our failure to determine the presence of reducing sub- 

 stances after the feeding of the other carbohydrates, glucose, maltose 

 and sucrose, which lacked the power of in any way effecting a change 

 in the flora. 



Since lactose and dextrin so readily effect a simplification of the 

 intestinal flora in man also, attempts were made to demonstrate their 

 presence in the stools of subjects receiving them. The experiments on 

 lactose alone have been carried to completion, and are presented here. 



The stools of four subjects (A, C, D and L) who received 300 

 grams, and of a fifth who took 400 grams, of lactose daily for ten days, 

 in addition to the daily diet, were studied at some length. Besides the 

 usual bacteriological examinations for the determination of type dis- 



