HISTORICAL REVIEW 9 



high protein diet caused an increase in the relative numbers of putre- 

 factive bacteria, which could be reduced again by the addition of lac- 

 tose to. the meat diet. Starch appeared to foster the amylolytic types. 

 They concluded that milk owes its beneficial action to the lactose, which 

 is absorbed slowly from the intestine. On several occasions it was 

 found in the feces of rats to which it had been fed. It was claimed 

 that the transforming influence of lactose could not be due to lactic 

 acid produced from the sugar, because it was impossible to demonstrate 

 increased acidity of the intestinal contents of the white rats. 



Throughout the above series of investigations Rettger and his asso- 

 ciates observed that B. acidophilus was an almost constant inhabitant 

 of the intestines of chickens of all ages and of white rats, and that the 

 administration of milk and lactose, and to a limited extent raw grains, 

 stimulated proliferation of this organism, and that unless such favorable 

 dietary agents were fed the number of acidophilus bacilli was held at 

 a low level. It was quite apparent then why the ingestion of milk soured 

 with B. hvlgaricus has such a marked transforming influence on the 

 intestinal flora, and that what at first sight appears to be B. bulgaricus 

 is nothing more than an invigorated B. acidophilus (1915, page 27). 



Weiss (1904) had demonstrated the presence of large numbers of 

 B. acidophilus in the intestine of man after the administration of milk. 

 Sittler (1908) called attention to the relation of intestinal organisms 

 to the diet. He attributed the predominance of B. bifidus in the feces 

 of breast-fed infants to the lactose in the mother's milk, basing his con- 

 clusions largely on the observation that cow's milk reinforced with lac- 

 tose causes the establishment of a similar flora. He noted also that 

 malt soup exerts the same influence, while sucrose eff'ected no trans- 

 formation. De Gasperi (1911) claimed that bread or mixed grain 

 caused the establishment of B. hifidus, whereas the substitution of meat 

 for bread or grain brought about a preponderance of B. coli and 

 Proteus vulgaris. 



That a mixed diet of milk and other staple foods causes a more 

 marked change in the bacterial flora than an ordinary diet without the 

 milk was shown by Fischer (1903) and confirmed by Sittler (1910). 

 Steele (1908) came to the conclusion that the regulation of the amount 

 and character of food is the most efficient means of checking excessive 

 bacterial activities in the intestine, while Friedenwald and Leitz (1909) 

 held that regulation of diet and evacuation of the bowels constitute the 

 most effective method of reducing the excessively high bacterial content 

 of the bowel. Harris (1912) fully agreed with the conclusions of 

 Friedenwald and Leitz. 



Herter and Kendal (1909) noted a definite correlation between 

 specific types of bacteria and the chemical composition of the ingested 

 food. They observed a gradual but rapid substitution of an acido- 

 philic, non-proteolytic type of flora for one that is strongly pro- 

 teolytic, when the diet was changed from meat and eggs to milk and 



