366 ' MILK 



This discovery led to an extensive investigation of the group of 

 lactobacilli, and an attempt was made to co-ordinate the number of 

 bacilli described, to form in one group. The general characteristics 

 of bacilli of this group as given by various investigators are fairly 

 uniform, and the belief is justified that they are derived from one 

 parent form which has assumed slight alterations in properties due 

 to special conditions. The organisms are described as large bacilli 

 occurring singly or in filaments, producing large amounts of acid in 

 milk, sometimes more than 3 per cent, and being Gram-positive. 

 The descriptions are usually meager, owing to the fact that this 

 class of organisms does not grow well on ordinary media. The 

 term "acidophil" is sometimes encountered in relation to these 

 bacteria, a term that is misleading, because this group of bacilli is 

 acid resisting rather than acid loving. Neutral or slightly acid 

 media are, in reality, more suitable for cultivation than media con- 

 taining much acid. 



Bacilli of this group have been isolated by Emmerling from the 

 Armenian fermented milk, "mazun"; by Freudenreich in "kefir"; 

 by Finkelstein in the intestinal canal of both bottle-fed and 

 breast-fed infants; by Moro also in the stools of infants and de- 

 scribed under the name of Bacillus acidophilus. Other authors 

 who have given descriptions of similar bacilli are: Beijerinck, who 

 studied kefir and named the organism Bacterium caucasicum; 

 Leichmann called a similar bacillus Bacillus delbriicki; Rodella, 

 Henneberg (B. panis lermentati), Grigoroff (B. bulgaricus from 

 Yoghurt, the Bulgarian milk) are among the investigators of this 

 group of bacilli. Rhist and Khouri found Streptobacillus lebenis 

 in "leben," an Egyptian fermented milk. Grixoni examined the 

 Sardinian milk, "Gioddu," and discovered a similar organism. 

 Weigmann, Gruber and Huss, Duggeli, Piorkowski, and Ltirssen 

 and Kiihn described members of this group-. Sewerin recognized 

 the identity of Bacillus bulgaricus and Streptobacillus lebenis, and 

 called attention to the fact that some strains form a slimy product, 

 while others do not. 



The colony formation of lactobacilli has been studied by sev- 

 eral authors. Mereschewsky distinguished two strains, one of 

 which formed small colonies, likened to grains of sand, while the 

 other strain formed colonies with woolly edges and of considerable 

 size (Figs. 172 and 173). 



Under the name Boas-Oppler bacillus the lactobacilli received 

 attention first from Boas and Oppler. Further studies were pub- 

 lished by Strauss, Schlesinger and Kaufmann, Heinemann and 

 Hefferan, Gait and lies, and Heinemann and Ecker. Kuntze 

 was the first to suggest the identity of the Boas-Oppler bacillus 

 with the lactobacilli, and this suggestion was shown to be true 



