120 TRANSFORMATION OF THE INTESTINAL FLORA 



for B. acidophilus. As this organism is normally present in the intes- 

 tine, though usually in small numbers, and merely requires a stimulus 

 to further development, which is furnished by the dextrin and lactose, 

 the conditions for its development upon the administration of these 

 carbohydrates become even more favorable than for any of the other 

 intestinal organisms. This theory was advanced by Hull and Rettger 

 (1917) who also reported the presence of a reducing substance in the 

 feces of rats fed on lactose. The other carbohydrates used in this 

 investigation, on the other hand, do not reach the large intestine, where 

 bacterial activities are at their greatest, and hence are unable to exert 

 any influence on the putrefactive processes going on here. 



That the stimulating influence of lactose and dextrin is not due to 

 acids produced from these substances is strongly indicated by the 

 absence of increased hydrogen ion concentration in the fecal materials 

 from the caecum and colon of rats and from the feces of men receiving 

 these carbohydrates. This observation is in harmony with those of 

 other investigators. Hirschler (1886) concluded that the presence of 

 acid in the intestine is not in itself sufficient to prevent putrefaction. 

 Winternitz (1892) claimed that lactose when fed to animals or man 

 exerted an inhibitory influence on putrefaction, but that this action 

 was due to the sugar itself, and not the lactic acid formed from it. 

 Rovighi (1892) pointed out that the ingestion of lactic acid had only 

 a very slight influence on intestinal putrefaction, and Fischer (1915) 

 observed that acid played no part in inhibiting indol formation. 



While the multiplication of B. acidophilus is stimulated to a greater 

 or less extent, the transformation brought about by the feeding of one 

 gram of lactose or dextrin to white rats or 150 grams to man seldom 

 amounted to more than 50 per cent, and with a few exceptions in man, 

 there was no radical suppression of other types of bacteria developing 

 in the intestinal tract. In order to obtain complete transformation 

 two grams of lactose are required for rats, and as a rule 300 grams 

 for man. This is in accord with findings of Hull and Rettger (1917), 

 who showed further that with increases of lactose beyond two grams 

 daily B. bifidus tended more and more to acquire prominence in the 

 feces of white rats, and that when as much as three grams was fed 

 daily the Tissier organism assumed the chief role, in place of B. 

 acidophilus. 



The successful transformation brought about in rats by the com- 

 bined action of one gram of lactose or dextrin and one cubic centimeter 

 of B. acidophilus suspension, and of 150 grams of lactose and 150 cubic 

 centimeters of culture in man offers a new avenue of approach to the 

 intricate field of bacterial implantation within the intestinal tract. 



What appears to us to be of no less significance is the demonstration 

 in the present investigation that the administration of the acidophilus 

 suspension alone, that is, without added carbohydrates, results in the 

 implantation of B. acidophilus and suppression of the other bacterial 



