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 attempts to prepare the alcoholic ferment, and therefore assumes that such a ferment does not exist in the yeast, but, that the sugar is decomposed in the yeast-cell in the same way as the albumen is decomposed 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, which 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 latter 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 instance, 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 methods 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 convert albumen into carbonic acid, water, and urea, or uric acid, with the absorption of oxygen.
The fact that sufficiently reduced dogs and chickens would represent two different ferments shows clearly that the differences which are observed between yeast, the lactic ferment, and the butyric ferment, may be considered due to the inner organization of these most