226 BACTERIOLOGICAL METHODS 



oryza, and subsequently the alcoholic fermentation is carried on 

 by the saccharomyces. The method of preparing arrak is 

 therefore similar to that of making sake. More generally, 

 however, arrak is made from fermented molasses. 



6. Yoghiirt. — This is Bulgarian sour, thick or klabbered 

 sheep's or cow's milk. The milk is boiled and evaporated to about 

 half its volume, then cooled to about 45° C. and the ferment known 

 as maya or podkoassa is added. The maya is simply the dry 

 residue from a previous fermentation. The fermented product 

 has a sour aromatic taste. The most important organism in this 



Fig. 80. — Showing a Kephir granule or mass natural size and three types of bacteria 

 found in Kephir. — (Marshall.) 



fermentation is the Bacillus hulgaricus. Other bacilli, cocci 

 and yeasts are also present. The Yoghurt tablets of the market 

 are presumably pure cultures of the Bacillus hulgaricus. 



7. Kephir. — Kephir is an effervescent alcohohc sour drink 

 made from the milk of the cow, sheep or goat. This is also a 

 Bulgarian preparation. The kephir granules or seeds are simply 

 more or less dry residues of a pre^'ious fermentation and may be 

 obtained in the market. These granules are composed of the 

 organisms which give rise to the fermentation products, principally 

 Dispora {Bacillus) caucasica and several species of streptococci. 

 These several organisms are supposed to form a mutualistic as- 



