EXPERIMENTS WITH WHITE RATS 



41 



When, however, the diets furnishing only one gram of lactose or dex- 

 trin were reinforced with one cubic centimeter of the standard suspen- 

 sion of B. acidophilus, a very marked transformation of the intestinal 

 flora from the mixed type to one completely dominated by B. acidoph- 

 ilus was effected. Within six to eight days after the administration of 

 these diets this organism constituted 90 to 99 per cent of the total flora. 

 The Veillon tubes contained numerous colonies of B. acidophilus, and 

 no gas, while the stained films revealed a picture of practically all Gram- 

 positive acidophilus-like bacilli. (See Tables 15 to 18, and Charts 

 19 to 22.) 



The following experiments which extended over a period of thirty 

 days were undertaken to determine whether the ingestion of one cubic 

 centimeter of B. acidophilus suspension alone would maintain the sim- 

 plified character of a flora already established by the feeding of two 

 grams of lactose or dextrin, or the above-mentioned combination of 

 sugar and B. acidophilus suspension. Nine rats which had been on the 

 basic diet for five days and had developed the typical mixed flora were 

 divided into three lots of three each. The first lot was given two grams 

 of lactose daily ; the second, one gram of lactose and one cubic centi- 

 meter of the bacterial suspension ; and the third, two cubic centimeters 



CHART 19 



Curve indicating average percentages of B. acidoph- 

 ilus appearing in fecal specimens from rats 

 fed on a diet containing lactose and 

 B. acidophilus 



C>/c/- m grams 

 /OO Bread lo . OGeiS, Laci-o-sG J 

 S-acidojohi/c/s 1 c. 



So 



70 

 60 



s50 



40 



20 



ire.MS'O'4 Ift S^ 



z A e e /o /s 14 



