50 TRANSFORMATION OF THE INTESTINAL FLORA 



ingestion of one gram of lactose in connection with one cubic centimeter 

 of the bacterial suspension there was an increase in the number of 

 aciduric bacteria in the same way and to the same extent as in the 

 experiments in which one gram of lactose or dextrin alone was fed. 

 The aciduric organisms were found to be B. acidophilus, and not 

 B. hvlgaricus. (See Charts 24 and 25.) The characteristic fluffy 

 colonies were picked off the whey agar plates and inoculated into the 

 maltose broth. 



The stimulation of the proliferation of B. acidophilus, and not of 

 B. hulgaricus, as the result of the ingestion of one gram of lactose and 

 one cubic centimeter of the standard bulgaricus bacillus suspension, is 

 a clear indication that B. hulgaricus is incapable of adapting itself to 

 the intestinal environment of the white rat. The intestinal flora of the 

 control rats receiving two cubic centimeters of B. acidophilus suspen- 

 sion or one cubic centimeter of the suspension plus one gram of lactose 

 was completely transformed from the complex to the simple aciduric 



In order to determine whether any of the ingested bulgaricus bacilli 

 survive for any length of time in the intestine, the test animals were 

 killed twenty-four hours after the last feeding of B. hvlgaricus material, 

 and bacteriological examinations of the different sections of the intes- 

 tine made. It became quite apparent that B. hulgaricus did not sur- 

 vive in any portion of the enteric tract, and the results were the same as 

 when one gram of lactose or dextrin alone was fed. 



CHART 24 



Curves indicating average percentages of B. hul- 

 garicus and B. acidophilus appearing in fecal 

 specimens from rats fed on a diet con- 

 taining lactose and B. bulgaricus 



6o 



40 

 JO 

 SO 

 lO 



Dief 



\ ^roms. 



BreQ<i /O 



c LacTos^ / 



fn e.bulooncus ICC 



2 4 e O /O 12 14 



