66 Profs. H. Marshall Ward and J. Eeynolds Green. 



that the organism — unlike kephir — does not ferment the milk itself, 

 but only the added sugar, and that the clots are simply due to the acids 

 liberated as the sugar is destroyed, a conclusion fully borne out by 

 subsequent investigations. 



A preliminary experiment with the ginger-beer plant showed that it 

 also behaves in the same way as regards milk ; the fermentation only 

 occurs if sugar be added, and lasts only so long as any sugar remains. 



In the cases both of the present organism and of the ginger-beer 

 plant, if a clump be placed in sterilised beer wort, the resulting fermen- 

 tation gives a frothing liquid with a beer-like taste and smell, and a 

 rapid deposit of yeast occurs. This primary fermentation is very soon 

 finished, and it is abundantly proved by the experiments that this 

 medium favours the yeast — or one of the yeasts — in the clumps, so 

 that we may regard this fermentation as merely a particular case of 

 an impure alcoholic fermentation, such as is got in ordinary brewing. 



During these preliminary trials, and with the object of testing 

 whether acidification of the liquid from the first would affect the matter, 

 it happened to one of us to select lemon-juice as the medium in one 

 case, partly to acidify the medium, and partly to add vegetable matter 

 other than sugar. The result was somewhat astonishing. The mixture 

 of soda-water, sugar, and lemon passed into violent fermentation in 

 three days, and carbon dioxide came off abundantly, under a pressure 

 of about 12 inches of mercury, and continued to do for many days. 



Such a flask started on April 9, 1897, was evolving gas actively on 

 the 12th ; this went on without any apparent diminution until May 24, 

 and even on June 24 gas was still coming off, though now under less 

 pressure. Xo sugar had been added in the interval, and the flask, 

 still unopened, remained on a side bench in the laboratory until 

 January 18, 1898. On that date it was opened and examined. It 

 still stood at a pressure of 6 inches of mercury, and gave off gas as 

 soon as the pressure was reduced. The microscopic examination 

 showed that here, again, as in the beer wort, the medium had favoured 

 one of the yeasts, and although the bacterium was discoverable, it was in 

 abeyance, and the compound organism as a whole was not increasing. 



In another similar case the flask was started on May 28, 1897, and 

 the pressure of the gas evolved was still supporting nearly 12 inches of 

 mercury on April 23, 1898, and again only yeast predominated in the 

 deposit, and examination showed this to be fully alive; it at once 

 renewed its activity when placed in sugar solutions. 



These preliminary experiments will suffice to show that we have in 

 this compound of associated organisms an agent or agents capable of 

 setting up very active fermentation in various saccharine liquids, such 

 as ordinary sugar and water, or soda-water, beer wort, milk, and sugar, 

 or an infusion of vegetable substance, such as lemon pulp, and it is 

 clear that the fermentation, though differing in details in each case, 



