484 MANUAL OF MILK PRODUCTS 



bacteria, which are known to occur normally in the intestines, 

 is so slight that they can be distinguished only with difficulty, 

 and he suggests that belief on the part of some investigators 

 that B. bulgaricus becomes established in the intestines was 

 caused by their inability to distinguish between these two types. 

 His work tends to show that while the B. bulgaricus appears 

 in the feces during the feeding, it persists for only a few days 

 after the ingestion of cultures ceases. 



The situation may, perhaps, be fairly summed up by saying 

 that while there is no conclusive evidence that B. bulgaricus is 

 able to establish itself in the intestines in such a way that other 

 bacteria are driven out, it is undoubtedly true that in many 

 cases marked improvement has resulted from the ingestion of 

 milk cultures made from it. It is by no means certain, how- 

 ever, that the results which have been obtained by the use of 

 milk cultures have been attributable to any peculiar virtue in 

 the organism itself. It has been held by some investigators 

 that the intestinal flora may be radically changed by a funda- 

 mental change in the diet. 



Distaso and Schiller state that when rats were fed a diet 

 of lactose and dextrine the heterogeneous intestinal flora was 

 changed to one consisting almost exclusively of Bacillus 

 bifidus, the characteristic acid-forming bacillus of the intes- 

 tines. This is in accord with the earlier work of Herter and 

 Kendall, who found that the nature of the bacterial flora 

 of the intestines could be promptly and distinctly changed by 

 a radical change from a diet high in protein to one in which 

 carbohydrates predominated, or vice versa. A high-protein 

 diet caused symptoms of intestinal putrefaction. A change 

 to a carbohydrate diet resulted in a reduction of the putrefactive 

 bacteria, an increase in the acid-forming bacteria, and the dis- 

 appearance of the indications of autointoxication. Similar 

 results were obtained in an investigation carried on by Rettger. 



This work was very comprehensive, covering a long series of 



