PRESERVING VEGETABLES AND FRUIT. 221 



This concentrated wine-must, which is shipped in sealed tins, 

 is not in any case sterile, though the still living germs (particularly 

 yeasts) present therein are, by reason of the high concentration of 

 the liquid, incapable of development. If, however, the mass be 

 diluted with sterilised water, then fermentation ensues within a 

 short time. According to the experience of J. WOKTMANN (II.), 

 and also of the author himself, the employment of this must can 

 be recommended in laboratories dealing with Fermentation Physi- 

 ology. The dilution of i part of must with 4 parts of water yields 

 a nutrient medium exceedingly favourable for the cultivation of 

 higher fungi (wine yeasts), the low percentage of nitrogen being 

 improved by an addition of i per cent, of ammonium tartrate. 



The preservation of beer and wine by heating (Pasteurisation) 

 will be dealt with in a subsequent section of the second volume. 



