ALCOHOLIC FERMENTATION OF MILK. 93 



presence of a species of yeast, two species of cocci, one 

 species of sarcina, a bacillus which is probably the common 

 hay bacillus, and a widely distributed milk organism, O'idium 

 lactis (94). The relation of these different microorganisms 

 to the production of matzoon is quite unknown, although it 

 is probable that some of the bacteria bring about changes in 

 the ingredients of the milk .which make an alcoholic fer- 

 mentation possible, after which the yeast produces the alco- 

 holic fermentation. 



Kefir. This is an alcoholic beverage which was found 

 originally in the Caucasus Mountains where, from time 

 immemorial, the peasants have used an alcoholic fermenta- 

 tion of milk going, by this name. The method of prepara- 

 tion is simple. Milk is placed in leather flasks or sacs and 

 then there is added to the milk a material called Kefir grains. 

 These Kefir grains (Fig. 19) are small solid kernels which 



FIG. 19. 



A large-sized kefir grain and the three species of bacteria of which it is composed. 

 ( Freudenreich. ) 



are kept in families and handed on from generation to 

 generation. The flasks are hung up in the sun in winter and 

 in the shade in summer and shaken occasionally. The milk 

 undergoes a fermentation of which alcohol is one of the pro- 



