3H PHENOMENA OF PUTREFACTION. 



ments on the behaviour of fifty-two species of bacteria towards- 

 twenty-one different organic acids was performed by A. MAASSEN 

 (I.), principally on medical grounds. One result of this research 

 was the discovery of a new characteristic valuable in the bacterio- 

 logical analysis of water for the differentiation of Bacillus typhi 

 abdominalis from Bacterium coli commune viz., tricarballylic acid, 

 COOH CH 2 CH.COOH CH 2 COOH, which is attacked and 

 partly destroyed by the first-named organism, but is left altogether 

 untouched by the second. 



More minute investigations into the fermentation of the above- 

 named organic acids would be of value, not only in solving the 

 preliminary questions involved in the study of loss of colour in 

 wine, but also in connection with the decrease in the acidity of 

 wines and fruit wines during storage, a phenomenon well known 

 in practice and one quantitatively examined by PAUL BEHREND' 

 (I.) and by P. KULISCH (I.). This decrease so long as it remains 

 within narrow limits is looked upon with favour, as contributing 

 to the rounding and improvement of the flavour of the maturing 

 wine. If, however, it proceeds too far and the acidity falls too low, 

 then a proportionate decrease in the power of the beverage to with- 

 stand disease (especially loss of colour) ensues. This fermentation 

 of the acids is, as already stated, principally effected by fission 

 fungi, on which point a few particulars have been given by 

 MULLER-THURGAU (V.). To a small extent these acids are consumed 

 by the yeast in the primary fermentation, so that the quantity 

 present in the young wine is less than in the must. Consequently, 

 if the total acidity in the former is found greater than that of the 

 fresh grape-juice and fruit-must, the excess is due to the carbonic 

 acid held in solution. 



Grapes from vines infested with mildew, whereby both de- 

 velopment and sugar formation are retarded, yield wine poor in 

 alcohol and consequently of low resisting power. Such wine fre- 

 quently becomes diseased, and is then known in France as vin 

 mildiouse. Here again bacterial agency is at work, the rod-shaped 

 organisms forming many-jointed chains and reproducing so abun- 

 dantly, that they finally accumulate as a thick sediment. U. GAYON 

 (II.) regards this malady as identical with that causing loss of 

 colour, because he identified in vins mildiouses the same volatile 

 acids (acetic and propionic acids) as have been discovered by 

 others, e.g. E. DUCLAUX (XII.), in vins tournes. 



The mannitic fermentation of wine, which presents a certain 

 oppositeness of character to the malady known as loss of colour, 

 will be described now, because otherwise no suitable occasion 

 would arise. This complaint does not wait to attack the finished 

 wine, but even makes its appearance at the stage of primary fer- 

 mentation. If the surrounding temperature keeps above 30 C. r 

 then alcoholic fermentation is confined within narrow limits, and 

 an opportunity is thus afforded for the development of certain 



