102 Dairy Bacteriology. 



Europe, B. Bulgaricus has not been found, but only the 

 ordinary lactic acid bacteria. 



Several alcoholic drinks made from milk, such as kefir 

 and koumiss, have been originated among the nomadic 

 tribes of Western Asia. Kefir is prepared from cow's 

 milk by adding the kefir ferment in the form of grains 

 which contain a number of kinds of bacteria and a yeast. 

 The acid-forming bacteria impart a sour taste to the 

 fermented milk, while the yeast forms carbon dioxide 

 and about two per cent of alcohol. If the milk is al- 

 lowed to ferment in stoppered bottles, the resulting 

 product will be an acid effervescing drink, which is 

 claimed to be more easily digested than sweet milk. This 

 drink is used frequently in the treatment of invalids but 

 it is improbable that it is more easily digested than or- 

 dinary soured milk or butter milk. The grains are re- 

 moved from the fermented milk, and are then added to 

 a quantity of fresh milk, or they may be dried and kept 

 for future use. When needed again, they are soaked in 

 water, then added to the milk. 



Koumiss is made in Russia from mare's milk and has 

 much the same composition as kefir. In America and 

 Europe it is made from cow's milk, by adding cane 

 sugar and compressed yeast. The yeast ferments the 

 cane sugar while the acid-forming bacteria ferment the 

 milk sugar. There is thus obtained a drink that is sim- 

 ilar in composition to the real koumies, in which both 

 the acid and the" alcohol come from the fermentation of 

 the milk sugar. In koumiss and kefir the curd is very 

 finely divided and will remain in suspension for a long 

 time as with butter milk. 



Determination of the cause of taints in milk. It is 

 often of the greatest importance to be able to locate the 



