EXPERIMENTS WITH WHITE RATS 63 



Benedict's solution were made in connection with the hydrogen ion 

 determinations . 



The results show clearly that, while the hydrogen ion concentration 

 varies normally within certain limits, the figures for the rats harboring 

 a simplified flora strongly dominated by B. acidophilus run almost 

 parallel with those of the animals having the usual mixed flora. The 

 hydrogen ion concentration limits remain practically the same. 



It was found also, in association with the above tests, that the feces 

 of the lactose- and dextrin-fed rats contained reducing carbohydrates 

 and a corresponding flora consisting almost entirely of B. acidophilus, 

 thus further emphasizing the observed relationship existing between in- 

 complete absorption of the carbohydrates and simplification of the flora 

 through dextrin and lactose feeding. 



CONCLUSIONS 



Diet is a controlling factor in the regulation of bacterial activities in 

 the intestinal canal of albino rats. 



B. acidophilus of Moro is a common inhabitant of the alimentary 

 tract of the white rat. 



Lactose and dextrin, when given in sufficient amounts, bring about a 

 marked transformation of the intestinal flora in which B. acidophilus 

 assumes particular prominence and may even completely supplant all 

 other types of bacteria. Maltose, glucose and sucrose, on the other 

 hand, have very little or no tendency to induce such a change. 



The same results are obtained when one gram of lactose or dextrin 

 is reinforced with one cubic centimeter of the standard B. acidophilus 

 suspension as by the daily feeding of two grams of either of these carbo- 

 hydrates alone in conjunction with the basal diet of bread and meat. 

 In both instances the bacterial transformation to the simple aciduric 

 type is practically complete. 



The daily administration of two cubic centimeters of the B. acidoph- 

 ilus suspension (nephelometer five) without the addition of the carbo- 

 hydrates also leads to a profound change in the character of the flora 

 of the white rat, and an implantation of B. acidophilus to the extent of 

 90 to 99 per cent of the total flora is effected. 



The simple character of the new flora persists so long as one or 

 another of the above diets or preparations is continued, but reverts 

 gradually to the normal or usual mixed type within five or six days 

 after a return to the basal diet. 



B. bulgaricus, which is not an intestinal organism, is unable under 

 any circumstance to establish itself in the alimentary canal of the 

 albino rat. Even the daily administration of five cubic centimeters of 

 the B. bulgaricus suspension exerts no influence on the bacterial popu- 

 lation of the intestine. 



