418 



ALFRED H. RAHE 



not to the accumulation of acid products of growth, but rather 

 to the exhaustion of essential amino acids or other growth pro- 

 moting substances. 



Aside from their action on mannite and milk all of the strains 

 of B. hifidus acted uniformly, and if we limit ourselves to the 

 easily applied cultural tests in 0.5 per cent agar we find but two 

 possible types of this organism. Even that arrangement would 

 require defense, since the action on mannite was always slight. 

 While the nature of B. hifidus is not yet entirely settled, Noguchi's 

 (1910) demonstration of its pleobiosis has lately been confirmed 



TABLE 5 



Showing the greater activity of B. hifidus in medium 2, -prepared from broth which 

 had previously been subjected to the more prolonged action of B. coli 



by Howe (1917), and in view of its protean nature, we must 

 keep in mind that we are here dealing with the aciduric phase 

 of this organism only. In its aciduric phase, then, the Bacillus 

 hifidus is a non-gasforming organism that may or may not 

 clot milk but ferments maltose, glucose, lactose, sucrose and 

 raffinose. 



The figures shown on opposite page illustrate the relative 

 frequency with which the individual members of each of three of 

 the groups of aciduric bacilli were found during the course of 

 the present investigation. 



It is unfortunate that, except in case of B. hulgaricus, 

 the action on milk could not be correlated with the other cul- 



