82 MICRO-ORGANISMS AND FERMENTATION. 



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; the fermentation, if the liquid is 

 frequently shaken, is completed in two to three days. It now 

 contains about two per cent, of alcohol. This result is pro- 

 bably brought about by the simultaneous action of the 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 carbon dioxide result from the 

 action of the yeast cells. Then, as the fermented milk, 

 according to some investigators, contains less coagulated 

 caseine than ordinary sour milk, it may be assumed that the 

 Dispora is also able to partly liquefy (peptonise) the co- 

 agulated caseine, perhaps with the help of the gelatinous mass 

 secreted by the bacterium, which is found in the kephir-grains, 

 but is not present in the fermenting milk. According to 

 recent investigations of HAMMARSTEN, however, the amount of 

 caseine does not appear to decrease, but a part of it undergoes 

 certain alterations, inclusive of physical change, in consequence 

 of which it becomes more finely flocculent. The deviation in 

 these results may possibly originate in the different biological 

 composition of the kephir-grains selected. 



FREUDENREICH constantly found Dispora Caucasica in a 

 number of kephir samples, which readily developed on milk- 

 agar plates and in milk-sugar broth at a temperature of 35 C.; 

 the bacilli frequently have resplendent points at both ends, 

 and FREUDENREICH presumes that this phenomenon coincides 

 with the formation which KERN regarded as spores ; unmis- 

 takable spores, however, were not found. 



Further, there occur in all samples two lactic acid coccus 

 forms and a yeast-species. One of the cocci (Streptococcus a) 

 forms diplococci and chains, and produces in milk-sugar 

 gelatine large, white colonies, which show a coarse granulation 

 near the border ; the best temperature for the growth of this 

 species is about 22 C. ; it coagulates milk most rapidly at 

 35 C., and contributes essentially to the production of a 

 sourish taste and fine flocculent appearance. The other coccus 

 (Streptococcus b}, which likewise forms diplococci and chains, 



