FERMENTS, FERMENTATIONS, AND LIFE. 269 
within it fermentation of the sugar, that is to say, the 
formation of a little alcohol; and this in its turn is sus- 
ceptible of the passage into acetic fermentation, giving the 
pulp an acid taste. At last the pulp itself is destroyed by 
various fungous growths, When a fruit decays and takes 
a more or less unpleasant flavor, this depends on the in- 
tervention of ferment-cells of atmospheric crigin, and on 
the production of acid or alcoholic substances. An able 
micrographist, Engel, who has lately studied these phe- 
nomena minutely, discovers that the yeast-cells which thus 
produce alcoholic fermentation in the juices of fruits present 
some slight differences in various fruits, neither do they 
have the same morphological character as those of grape- 
must or beer-wort. Varieties occur in these cases, corre- 
‘sponding to the different media in which the nutrition of 
the little fungus takes place. 
The microscopic fungi of the atmosphere play as in- 
teresting a part in the alteration of wines. These grow 
acid, change, become filmy or oily, or take on besides a 
decided bitterness. All these sicknesses depend on the 
development of different little plants recognized and de- 
scribed by Pasteur; and this scientist, not stopping at the 
solution of the nature of these disorders, has sought the 
means of preventing them. Resting on some former ob- 
servations by D’Appert, he conceived the idea of subject- 
ing wines to the action of a very high degree of heat, so as 
to destroy the yeast-germs. There was no possibility of 
doubt as to the destruction of these germs and the preven- 
tion of any further change, but it might well be asked wheth- 
er the delicacy and bouquet of certain wines would not 
be endangered by the effects of heating. Long-continued 
experiments prove not only that heating is an excellent 
method of preventing sickness in wines, but also that, in- 
stead of impairing their exquisite qualities, it ripens and 
strengthens them. The recorded minutes of tastings of- 
