8 TRANSFORMATION OF THE INTESTINAL FLORA 



one of a more complex character, which eventually resembles the mixed 

 flora of an ordinary adult. 



Moro (1900a) claimed that his Bacillus acidophilus was the pre- 

 dominating organism in nurselings' stools, but later admitted Tissier's 

 claims. Passini (1903), Moro (1905), Tissier (1905), Rodella (1905), 

 Sittler (1908) and Bahrdt and Beifeld (1910) concluded that diet 

 plays an important role in determining the types of intestinal micro- 

 organisms. They corroborated Tissier's earlier observation, namely 

 that Bacillus bifidus is the predominant organism in the stools of breast- 

 fed infants and that there is a more varied and less constant flora in 

 the feces of bottle-fed babies. Spiegelberg (1899) reported a scarcity 

 or absence of liquefying bacteria in the stools of normal nurselings. 



Rettger and Horton (1914) noted a marked simplification of the 

 intestinal flora of white rats soon after they were shifted from the 

 usual mixed diet of grains and vegetables to one containing starch, lard, 

 protein-free milk and purified proteins, the Gram-positive organisms 

 of the acidophilus and bifidus types constituting eighty-five to one hun- 

 dred per cent of the flora. Hull and Rettger (1914) observed that 

 mixed grain feed tends to transform the flora of the rat, but that no 

 profound change takes place until milk or lactose is administered in 

 addition to the regular diet. The preponderance of B. acidophilus 

 over other organisms was brought about within three days after a diet 

 of vegetables and bread was followed by one of mixed grain and milk. 

 When lactose was fed in appreciable amounts the transformation period 

 was very short, and the change in type of bacteria was practically 100 

 per cent. It was noted, however, that the B. acidophilus phase was 

 often more or less temporary, this organism giving way to B. bifidus. 

 In the milk-feeding experiments the acidophilus phase was, as a rule, 

 the more permanent, B. bifidus seldom gaining the ascendency. Of par- 

 ticular interest in this investigation was the failure of the authors to 

 implant B. bulgaricus by the ingestion of milk cultures and water 

 suspensions of this organism. 



Rettger, Kirkpatrick, Jones and Card (1914 and 1915) employed 

 several thousand chicks in their studies on the influence of milk feeding 

 on growth and mortality, and found that the unique properties of this 

 food exist in the milk per se, and not in any milk acids or milk-souring 

 bacteria. The chicks received unpasteurized, sterilized and naturally 

 soured milk, as well as milk soured with pure cultures of B. btdgaricus, 

 and no diff'erences could be observed in the beneficial eff'ects of the 

 different preparations. These observations impressed upon the writers 

 the fundamental fallacies of Metchnikoff's interpretation of the sour- 

 milk therapy. Hull and Rettger (1917) confirmed the results of their 

 earlier work. They found, further, that two to three grams of lactose 

 are sufficient to establish an aciduric flora within three days. It re- 

 quired a longer time to transform the flora by milk feeding than by the 

 use of lactose, and the change was not so nearly complete. Meat or 



