FERMENTS, FERMENTATIONS, AND LIFE. 359 



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, torulaceas), 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." The 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 



