410 ALFRED H. RAHE 



occurred with equal frequency, while the former bacillus was 

 not so frequently encountered in house sewage or milk. In 

 human and animal feces as well as in saliva there is at times a 

 tendency towards the appearance of one species to the exclusion 

 of the other. Stomach contents from five cases of gastric car- 

 cinoma were examined and both types of organisms isolated, 

 thus disposing of the Boas-Oppler bacillus as a separate entity. 

 None of the carcinoma strains corresponded to B. bulgaricus, 

 differing in this from some strains isolated by Heinemann (1917). 

 The classification herein suggested is based on fermentation 

 tests. Among the aciduric bacilli, other than B. hifidus, colony 

 formation, morphology and staining properties are subject to 

 variation common to all. In the case of B. bulgaricus, action on 

 milk and possibly colony formation assume the importance of 

 distinct characters. 



BACILLUS ACIDOPHILUS 



As table 1 shows, it would be possible, on the basis of fermen- 

 tation tests to define six subtypes of B. acidophilus. Mannite 

 proved both here and elsewhere to be a very unsatisfactory test 

 substance, permitting a very meager development at best. If 

 we regard this alcohol as without value in differentiation the 

 number of types becomes reduced to four. It is evident that 

 the great majority of these organisms were milk clotters, thus 

 agreeing with the B. acidophilus of Moro. The organism of 

 Finkelstein does not possess this property. I am unable to 

 account for the rarity of the non-clotting bacillus in this instance. 

 In a previous investigation it was encountered with much greater 

 frequency (Rahe 1914). 



B. ACIDOPHIL-AEROGENES 



The variable behavior of this organism in milk was noticed in 

 the paper in which it was originally described (Torrey and Rahe 

 1915). The fermentation tests show a greater unity here than 

 was the case in the preceding group. Sixty-five per cent of the 

 cultures produced gas in all of the test substances if we except 



