380 



Bacteria in Relation to Country Life 



not only in the formation of lactic acid, but, also, in 

 changing the milk-sugar so that it may become ferment- 

 able to the yeast cells. In this country, kumiss is readily 

 prepared by the addition to cow's milk of a quantity of 

 cane-sugar and of ordinary beer yeast. The cane-sugar 

 is then caused by the yeast to undergo fermentation, 

 while the milk-sugar is changed into lactic acid by bac- 

 teria. 



Matzoon. — Matzoon is a milk beverage of Armenian 



Fig. 61. Microdrganisms of Armenian matzoon. (After Weigmann, Gruber 

 and Huss.) 



