FERMENTS, FERMENTATIONS, AND LIFE. 259 
butyric acid and several analogous acids, equally strong 
in smell. To cite a last illustration, the decomposition 
of urine, giving rise to an abundant release of ammoniacal 
gases, is also the result of a fermentation; under the action 
of cells smaller than those of brewer’s yeast, the contained 
urea changes to carbonate of ammonia, rendering the liquid 
highly alkaline and strongly odorous. In short, the fermen- 
tations we have just described, and many others of the 
same kind, participate in the nutrition and development of 
microscopic beings, of an average size not exceeding some 
thousandths of a millimetre, and presenting the form some- 
times of spheroidal or of egg-shaped globules (as myco- 
derms, torulacez), sometimes of straight, bent, or curving 
rods (as vibrios and bacteria). These diminutive beings 
engender the ferment within the fermenting liquid itself, in 
the degree and rate of their propagation in it. 
There is another class of fermentations in which the im- 
mediate presence of definitely-shaped corpuscles cannot be 
traced. Thus diastasic fermentation consists in the trans- 
formation of starch into sugar under the action of a form- 
less yellowish matter, called “ diastase.” Amygdalic fer- 
mentation is that in which amygdaline becomes the essence 
of bitter-almonds, by the action of a like ferment, known 
as “synaptase.” ‘he former takes place in the vegetable 
embryo when the amylaceous matter of the seed is con- 
verted into a soluble sugar, which permeates the growing 
tissues of the plant. The latter occurs when bitter-almonds 
are crushed in water; on contact with the liquid, the mixt- 
ure of these odorless kernels takes the characteristic smell 
of the essence of bitter-almonds, which results from the 
fermentation of amygdaline. We regard as fermentations, 
moreover, a certain number of similar phenomena which can 
be produced with the implements of a laboratory, and which 
are constantly taking place in living organisms, of which the 
cause is a zymotic substance. There exists, for instance, in 
