5 14 THE POPULAR SCIENCE MONTHLY. 



supporters of this hypothesis have been obliged to resort to the theory 

 that the ferment in question is so readily decomposed that it can not 

 be isolated. The other hypothesis is based upon the failure of all at- 

 tempts to prepare the alcoholic ferment, and therefore assumes that 

 such a ferment does not exist in the yeast, but, "that the sugar is de- 

 composed in the yeast-cell in the same way as the albumen is decom- 

 posed in the organism of the mammalia. The fact that a small amount 

 of yeast can by degrees decompose a large quantity of sugar is of no 

 more account than that a dog, for instance, can by degrees decompose 

 many times his own weight of albumen. The fundamental difference 

 between the hypotheses, therefore, is, that one assumes the presence of 

 a ferment, while the other denies it. 



The former hypothesis was fully justified as long as the nature of 

 yeast and the ferments of the present were unknown ; but, since we 

 know the latter as definite chemical compounds, Avhich are also active 

 without the cell, and do not require this for the development of their 

 activity, we must strictly distinguish between their action and that 

 which we see produced only by the living organism or cell. The lat- 

 ter is not at all to be considered the effect of fermentation, until actual 

 evidence of the presence of a specific ferment is furnished. A simple 

 consideration will show that the decomposition of the sugar, as the 

 result of the vital action of the yeast-cell, may well be compared to 

 the conversion of albumen into carbonic acid, water, and urea, in the 

 higher organisms. If we assume the body of a mammal, a dog for in- 

 stance, to be reduced to the size of a yeast-cell, without any change in 

 its organization, we would manifestly obtain a microscopic organism, 

 which would act on albumen in the same way that yeast acts on sugar. 

 Its anatomy would be as inaccessible to us as that of the yeast-cell, 

 for the organs would appear to us as dots and threads, similar to the 

 grains which we find in the cells. The changes of the gases in the 

 blood, together with the processes which take place in the intestines 

 or in the liver, and which have so often been made the subject of the 

 most thorough investigations, would be beyond the reach of our meth- 

 ods and we could only determine that these organisms have the power 

 to convert comparatively large quantities of albumen into carbonic 

 acid, water, and urea, with the absorption of oxygen in short, the 

 process would be similar to that of yeast fermentation. If we had 

 chickens and snakes in the same diminutive state, we should find that 

 they would produce uric acid instead of urea. It would be in vain to 

 attempt to separate from these organisms a ferment which would con- 

 vert albumen into carbonic acid, water, and urea, or uric acid, with the 

 absorption of oxygen. 



The fact that sufficiently reduced dogs and chickens would repre- 

 sent two different ferments shows clearly that the differences which 

 are observed between yeast, the lactic ferment, and the butyric fer- 

 ment, may be considered due to the inner organization of these most 



