Page:Popular Science Monthly Volume 5.djvu/569

Rh what the illustrious Ehrenberg calls the milky-way of lower organisms, and no less essential for explanation of the processes of which we have traced the general course. As there is an ether wanting in life, so there is an ether endowed with life—a vital ether. Both are above denial; they surpass our reason, yet reason cannot but demand them. They elude the close grasp of experiment, yet experiment does not permit them to be avoided; they are unseen, and without them there could be nothing seen. The mind clings to them with the stress of all its power to embrace, perhaps because it feels a secret, mysterious affinity with them, perhaps because it is in substance of the same essence with them.

atmosphere, then, is the receptacle for myriads of germs of microscopic beings, which play an important part in the organized world. Penetrating agents of decay, baneful toilers for disease, they lie ever in wait for the chance to pierce the internal machinery of animals and plants, and create slight or grave disturbances within it. Life often resists or escapes them, but nothing can contest with them its deserted vesture. The corpse is their natural aliment, and death their chosen laboratory. There these lowest of created things work out their lofty destiny in the eternal drama of renewal of organic existences.

When the thin pellicle covering sweet fruits is torn at any point, an opening is made for atmospheric germs. Fermenting cells pierce the interior of the fruit, and produce within it fermentation of the sugar, that is to say, the formation of a little alcohol; and this in its turn is susceptible of the passage into acetic fermentation, giving the pulp an acid taste. At last the pulp itself is destroyed by various fungous growths. When a fruit decays and takes a more or less unpleasant flavor, this depends on the intervention of ferment-cells of atmospheric origin, and on the production of acid or alcoholic substances. An able micrographist, M. Engel, who has lately studied these phenomena minutely, discovers that the yeast-cells which thus produce alcoholic fermentation in the juices of fruits present some slight differences in various fruits, neither do they have the same morphological character as those of grape-must or beer-wort. Varieties occur in these cases, corresponding to the different media in which the nutrition of the little fungus takes place.

The microscopic fungi of the atmosphere play as interesting a part in the alteration of wines. These grow acid, change, become filmy or oily, or take on besides a decided bitterness. All these sicknesses depend on the development of different little plants recognized and described by M. Pasteur; and this scientist, not stopping at the solution of the nature of these disorders, has sought the means of preventing them. Resting on some former observations by D'Appert, he conceived the idea of subjecting wines to the action of a very high degree