372 MILK 



haustive study, which would show that the multiplicity of names 

 is useless, and that different types have been described where one 

 would answer the purpose. 



A simpler, although not as comprehensive, classification has 

 been proposed by White and Avery, namely: 



Type A: With LofRer's methylene-blue or with Neisser's stain 

 the protoplasm is homogeneously stained. Acid production 

 amounts to 2.7 to 3.7 per cent, lactic acid in milk. The lactic 

 acid formed is the inactive variety. 



Type B: With Lofiler's methylene-blue or with Neisser's stain 

 the presence of intensely staining granules may be demonstrated 

 in the protoplasm. Acid production amounts to 1.2 to 1.6 per 

 cent, lactic acid in milk. The lactic acid formed is the levorota- 

 tory variety. 



Finally, Rahe found that the ability to ferment maltose offered 

 a useful means for classification. Three types are distinguished 

 by this author, as follows: 



Type A: Which clots milk, but has no action on maltose. 



Type B : Which clots milk and ferments maltose. 



Type C : Which ferments maltose, but does not clot milk. 



Rahe extended this study, and in a recent publication states 

 that "the aciduric bacilli, including Bacillus bifidus in its aciduric 

 phase, may best be classified in accordance with their ability to 

 ferment certain carbohydrates." The author tested the fer- 

 mentative ability of his strains with maltose, sucrose, lactose, 

 raffinose, glucose, and mannite. 



It must be confessed that these attempts at classification serve 

 a useful purpose temporarily, but that they are still incomplete, 

 and perhaps of not sufficient b'readth. An exhaustive study of 

 the members of the group of lactobacilli, therefore, should be made 

 to bring a rational classification to a higher degree of perfection. 



The lactobacilli can be isolated by inoculating the material 

 containing them into a broth to which 2 per cent, of dextrose and 

 0.5 per cent, of acetic acid have been added. The acetic acid 

 inhibits the majority of other organisms present, and after trans- 

 fers for several days and incubation at a high temperature of about 

 42° to 45° C. the lactobacilli will usually be found in pure culture. 

 Inoculation into milk then will facilitate study. Plates in whey- 

 agar may be prepared so that pure cultures are assured, and 

 the colonies may then be transferred to slanted whey-agar. 



The fourth group of lactic acid bacteria, according to Lohnis' 

 classification, consists of micrococci, and these are derived chiefly 

 from the udder. It has been previously stated that the majority 

 of bacteria in milk while still in the udder belongs to the class of 

 micrococci or staphylococci. The type of this class is Staphy- 



