52 TRANSFORMATION OF THE INTESTINAL FLORA 



whatever. (See Tables 19 and 20, and Charts 26 and 27.) In both the 

 plates and the Veillon tubes essentially the same colony picture was 

 obtained as in the preliminary tests when the rats were reciving the 

 basal diet alone. Gas formation in the Veillon tubes was very pro- 

 nounced at all times. There was some increase in the relative number 

 of Gram-positive rods in the films prepared from the fecal suspensions 

 directly, due in all probability to the passage through the alimentary 

 canal of dead organisms of the B. bulgaricus type. 



It was impossible, also, to recover B. bulgaricus from the feces of the 

 rats that were fed two cubic centimeters of the living bulgaricus sus- 

 pension together with two grams of the lactose. However, the intestinal 

 flora of these animals was thoroughly simplified, the transformation 

 effect being indistinguishable from that obtained with the feeding of 

 two grams of lactose alone. 



Post-mortem examinations, made twenty-four hours after the last 

 feeding, failed to reveal the presence of B. bulgaricus in the different 

 parts of the digestive tube. (See Table 20.) Not one of the nine rats 

 receiving the suspensions of B. bulgaricus showed any evidence of this 

 organism in any portion of the intestine. On the other hand, all of 

 the animals which received two grams of lactose in connection with two 

 cubic centimeters of the bulgaricus suspension harbored a flora in the 

 feces and at the various levels of the intestinal canal which was wholly 

 dominated by B. acidophilus. (See Tables 21 and 22, and Charts 28 

 and 29.) 



The foregoing results corroborate the earlier findings of Hull and 

 Rettger and in themselves most conclusively demonstrate that B. bul- 

 garicus cannot be implanted in the intestine of the white rat even when 

 administered in enormous numbers. The decisive results obtained with 

 B. acidophilus proved beyond a doubt its adaptability to intestinal 

 conditions and its capability of implantation within the intestinal tract 

 of the albino rat. 



SLOW CARBOHYDRATE ABSORPTION IN THE INTESTINE 



AND ITS RELATION TO B. ACIDOPHILUS 



IMPLANTATION 



Of the various carbohydrates fed to white rats lactose and dextrin 

 alone exerted a simplifying action on the intestinal flora, bringing B. 

 acidophilus into great prominence. Since this organism is a normal 

 inhabitant of the lower intestine, it was thought that perhaps both lac- 

 tose and dextrin, in virtue of their slow absorption, reach the colon 

 where they provide optimum cultural and environmental conditions by 

 serving as readily utilizable sources of energy for B. acidophilus and 

 the closely related B. bifidus of Tissier. According to this theory, the 



