Page:Popular Science Monthly Volume 7.djvu/735

Rh and you will also understand that this example embraces the destruction of all the species by which life is manifested upon the face of the earth.

If I should describe the destruction of a single grape, abandoned to itself, I should show you only one of the laws of the phenomena; but there are two principal ones, and in order to pass them both in review I shall suppose that all the fruits of a vineyard have been gathered and placed in a gigantic heap, in an immense reservoir, as large as a mountain, if you choose. Under the influence of the weight the grapes are separated from the stems, broken more or less, and allow their contents to escape in the form of a sugary liquid. By a fortunate coincidence (which M. Colin might at his ease and by the aid of sentiment look upon as an express desire of Providence to furnish man what is called wine), it happens that at the period of the maturity of the grape its surface and that of the stems are covered here and there in the form of a fine dust by an extraordinary number of the germs of a small cellular plant which has the faculty, its germination once commenced, under the influence of a very small quantity of air, to multiply indefinitely in the entire absence of free oxygen gas—this was proved at our last meeting—and to provoke, correlatively with its life, the decomposition of sugar into carbonic-acid gas which is set free, and an alcohol which remains in solution in the liquid.

In the must of the grape the principal substance, after the water, is the sugar; it constitutes 20.25 parts in 100, sometimes even more; now, the decomposition accomplished by the ferment of which we have just spoken eliminates in the form of carbonic-acid gas more than half of this sugar, and thus a considerable portion of the organic matter of the grape returns to the atmosphere.

This singular phenomenon, which has struck the imagination of men ever since the beginning of the world, is accompanied by an intense heat and a bubbling of the whole mass, but as the sugar disappears the movement slowly ceases. As soon as quiet is restored, our immense cask is found to be filled with an alcoholic liquid which is the habitual drink of men living in southern countries. Scarcely has the carbonic-acid gas ceased to escape, when an attentive eye sees a pellicle form upon the surface, a pellicle which is extremely thin and insignificant in appearance, but in which reside a new life and new phenomena well worth our attention: this pellicle is formed of a mycodermic plant (of two, in fact, but for the sake of brevity I shall consider only one) which, strictly speaking, we might class with that one which has just flourished in our cask and decomposed the sugar, but which has now fallen inert to the bottom. Still, if our two little plants resemble one another in their anatomical structure, they are very different physiologically. The cells of the ferment which destroyed the sugar lived and multiplied without air; the new cells, on the other hand, spread over the surface of the liquid in an unbroken pellicle,