I IX.] Ke^r. 97 



Fungi with which we are acquainted, nor, as experiment has 

 shown, by those of which we are speaking. To make this 

 fermentation possible, the sugar must first be inverted, split 

 into fermentable kinds of sugar. According to Nageli (9, p. 12), 

 the formation of an enzyme which inverts milk-sugar is a 

 general phenomenon in Bacteria, and Hueppe has shown that 

 it is probable in the case of his Bacillus of lactic acid in par- 

 ticular; the inversion required in this case to enable the 

 Sprouting Fungus to set up alcoholic fermentation is the work 

 therefore of the Bacillus of lactic acid, or of the Bacterium of 

 the Zoogloea, or of both. 



Lastly, it is to be observed that the kefir is in the fluid state. 

 Coagulation of the casein does indeed take place, but either it is 

 from the first not in the homogeneous gelatinous form of 

 ordinary sour milk but in small lumps and flakes suspended in 

 serum, or the gelatinous coagulations which are sometimes 

 present at first are soon partially dissolved. It is evident then 

 that the casein, which has already been coagulated, is partially 

 liquefied (peptonised). This must be ascribed to the enzyme 

 formed by the Bacterium of the Zoogloea, because according to 

 our present knowledge the Bacterium of lactic acid has no power 

 to peptonise casein or otherwise liquefy it. 



This view, which corresponds in all important points with 

 Hueppe's brief communication on the subject, is in accordance 

 with the remarkable fact that the ferment-milk, by means of 

 which the kefir is prepared, contains a large number of actively 

 growing cells of a Sprouting Fungus and of Bacteria of lactic 

 acid, but no Bacteria of the Zoogloea, or only small and doubt- 

 ful quantities of them. The grains as a rule strictly retain 

 these, while they part with the sprouting cells to the milk. There 

 is obviously no objection to the supposition that enzymes pro- 

 duced from the grains pass over into the ferment-milk and co- 

 operate with it. 



In this way, as I have said, we may explain the formation of 

 kefir, and I gave this account of it in the first edition of 



K 



