ALCOHOLIC FERMENTS. 173 



botanical point of view and with reference to their chemical 

 action on the nutritive liquid. The time required for spore- 

 formation was very different for the different species; the 

 number of spore-forming cells and the number of spores 

 in individual cells also exhibited striking and constant 

 differences. In connection with this, it is remarkable 

 that the pure cultivated species show distinct differences 

 in fermentative power, in the production of those volatile 

 substances which impart a special bouquet to wine, and 

 finally in their power of resistance to different acids and 

 to high temperatures. As marked differences in taste are 

 produced by not a few species, MARX is justified in em- 

 phasising the practical importance of such investigations, since 

 it may thus become possible, by the addition of yeasts of 

 known properties to wine-must, to produce wines having 

 definite character as regards taste, etc. 



More recently AMTHOR has also investigated a number of 

 absolutely pure cultures of wine yeasts, and has detected 

 typical differences with regard to spore-formation, the time of 

 the fermentation, and in the chemical composition of the 

 wines produced. Similar results have also been obtained by 

 JACQUEMIN, EOMMIER, MARTINAND, and EIETSCH, in France; 

 MUELLER-THURGAU, in Switzerland; NATHAN and WORTMANN, in 

 Germany ; MACH and PORTELE, in Austria ; FORTI and PICHI, 

 in Italy ; some of the comparative experiments conducted 

 by these authors having been carried out on a large scale. 



The most thorough and extensive investigations into the 

 different behaviour of wine yeasts towards must are due to 

 J. WORTMANN. He states, as the general upshot of his investi- 

 gations, that the differences in the activity of the divers types 

 of genuine wine yeast are sometimes so great that they can be 

 detected merely through the chemical analysis of the fermenta- 

 tion products ; in other cases, however, they are of such a kind 

 that we can only convince ourselves directly of their presence 

 by means of our senses (smell and taste). Every type of 

 yeast shows some individual peculiarity more or less charac- 

 teristic of itself in the action it exerts on any must regardless of 

 its origin or variety. 



The number of the yeast-cells which are formed in a given 



