BACTERIA. 71 



fermenting milk. If one of the above-mentioned kephir- 

 grains is allowed to remain in milk, it will grow very slowly 

 and only attain, according to the researches of de Bary, a 

 double size after the lapse of several weeks. This author 

 considers it probable that under such conditions single 

 Dispora cells separate themselves and give rise to new 

 kephir-grains. According to the mode of preparation pub- 

 lished by A. Levy, kephir can also be obtained without the 

 addition of Kern's ferments. When milk which is becoming 

 sour is repeatedly and violently shaken, an effervescent alcoholic 

 kephir-like drink is obtained, which, as regards taste, etc., 

 does not perceptibly differ from kephir prepared with kephir- 

 grains. According to de Bary the kephir obtained by shaking 

 contained about one per cent, by volume of alcohol, whilst a 

 sample of the ordinary kephir contained only 0'4 per cent, by 

 volume (Schmiedeberg). According to the recent investiga- 

 tions of Duclaux, Grotenfelt, Adametz, and others, there are 

 also certain yeast-fungi which are capable of fermenting 

 milk-sugar by themselves, without the aid of bacteria (see 

 Chapter V.). 



The Ginger-beer Plant, which presents morphological 

 resemblances to the Kephir ferment, has been examined 

 from a botanical and biological point of view by Professor 

 Marshall Ward. If this ferment is introduced into 

 saccharine solutions to which ginger has been added, it 

 transforms them into an acid effervescing beverage, ginger- 

 beer. When fresh, it occurs as solid, white, semi-transparent, 

 irregular, lumpy masses, brittle like firm jelly, their size 

 varying from that of a pin's head to that of a large plum. 

 It induces an alcoholic fermentation in the saccharine solution, 

 which at the same time becomes viscous. Marshall Ward 

 isolated the numerous micro-organisms existing in the masses 

 described above, and gave accurate descriptions of a series 

 of yeast-fungi, bacteria and moulds, among which two 

 organisms proved to be essentially concerned in the fermen- 

 tation of ginger-beer. One of these is a Saccharomyces, 



