74 MICRO-ORGANISMS AND FERMENTATION. 



one including those which give more especially a pure and 

 mild taste, and another embracing those which yield more 

 especially a product possessing great keeping powers. Morpho- 

 logically the growths are distinguished from each other by the 

 fact that some are connected in chains, others not (Fig. 20 b, a)', 

 the latter are of the most frequent occurrence and widest range 

 in nature. These forms bear a certain resemblance to PASTEUR'S 

 " ferment lactique." The species represented in Fig. 2 a was 

 isolated by STORCH from a sample of butter having a pure and 

 full aroma. It forms in gelatine small globular colonies of a 

 pure white colour and with a smooth surface. In milk and 

 whey it occurs in oval or globular forms. These lactic acid 



FIG. 20 b. Lactic acid bacteria. (After STORCH.) 



bacteria display a vigorous fermentative activity, even at 

 as low a temperature as 20 C. 



QUIST has cultivated another species, which has been em- 

 ployed with success in practice. It occurs both as micrococcus 

 and in other forms, according to the different nutrient media 

 in which it is cultivated. In gelatine it forms small, 

 circular, slowly-growing colonies of a whitish-yellow colour. 

 In puncture-cultivations spherical colonies arise through- 

 out the puncture-channel, and in streak-cultures this 

 organism forms a continuous streak with wavy borders. It 

 was prepared from a sample of butter of remarkable aroma 

 and durability. 



