70 MICRO-ORGANISMS AND FERMENTATION. 



portant part in the cellulose fermentation, which is employed 

 in various branches of industry. 



4. KEPHIR-ORGANISMS. 



The so-called "Kephir" on which the investigations of 



Kern have thrown some light, is an effervescent alcoholic, 



and sour milk, which is prepared by the inhabitants of the 



Caucasus from cows', goats', or sheep's milk. It is prepared 



by adding a peculiar ferment, " kephir-grains," to milk. 



These are white or yellowish, irregularly-shaped, uneven 



grains, about the size of a walnut and of a tough gelatinous 



consistency, and when dried become cartilaginous and brittle. 



The most essential part of these grains consists of rod-like 



bacteria, which are connected in threads and have developed 



gelatinous membranes. Kern calls this bacterium Dispora 



Caucasica. Yeast-like fungi are also found in kephir-grains, 



and among these different varieties of true Saccharomycetes. 



In the preparation of kephir a little milk is first poured on the 



grains and allowed to stand for twenty-four hours ; the milk is 



then poured off, and the grains preserved for future use. This 



milk is now mixed with fresh milk, and poured into bottles 



which are corked, or into leather sacks which are tied ; after 



some days a fermentation has taken place. It now contains 



about two per cent, of alcohol. This result is probably brought 



about by the simultaneous action of the above-mentioned 



Dispora and the yeast cells in combination with the lactic 



acid ferments which are probably always present in milk. 



These ferments convert a portion of the milk-sugar into 



lactic acid ; the alcohol and a part of the carbonic acid 



probably result from the action of the yeast cells. Then, 



as the fermented milk contains considerably less coagulated 



caserne than ordinary sour milk, it may further be assumed 



that the above-mentioned Dispora is also able to partly 



liquefy (peptonise) the coagulated caserne, perhaps with the 



help of the gelatinous mass secreted by the bacterium and 



which is found in the kephir-grains, but is not present in the 



