GENERATION. The production of life has always been a favorite study of scientific minds. All labor, however, to this end, has really added little to our knowledge of the genesis of life. The theory of spontaneous gen eration has been a favorite dogma with many superior minds, and yet, again, we have no real facts to support the theory. Hence it soon began to lose ground, and is now generally denied by scientific minds. The following condensed arrangements of facts, as stated by the Chemist of the Department of Agriculture of the United States, some years ago, will illustrate how gen eration may become active, as well as give some means of preventing generation, as in preserving suhstances necessary to be kept intact. (See also Fermentation and Fungi.) In regard to the origin of yeast cells, for instance, we have to con tend with the same conjectures and diversity of opinion as when accounting for the sudden appearance of millions of infusorize in stagnant water, or in explaining the origin of intestinal worms. It has been stated that the yeast cells already existed in the juice of the living grape, and all other kinds of fruit able to yield ferment able juice, such as apples, pears, blackberries, etc. These minute vesicles,•it was said, might readily pass through filtering paper, but it is cer tain that filtered juice of fresh fruit when exam ined under the microscope, exhibits no solids, no organized ferment of any kind, but after two of three days apple or pear juice, for instance, will exhibit yeast fungi, and, at the same time begin to ferment. Hence the conclusion is inevitable that we have here to do with a spontaneous cell formation, called generatio equivoca or originaria; that is, the yeast plant may, without the media tion of a mother plant, originate in a liquid con taining, besides water, sugar, dextrine, (gum,) and albuminous matter. The experiments of Schulze, Schwann, Pasteur, Schroeder, and Dusch favor the idea that the germs of the yeast fungi are diffused in the air and water ready to germinate and multiply whenever a favorable opportunity presents itself, like the eggs of the infusoria which have actually been traced in the air, water, mist, and even snow. Profs. Worm ley and Sullivant, of C olumbus, 0., have carefully determined that even with the most powerful microscopes, vision is limited to objects of about one eighty-thousandth of an inch in diameter. Now, some infusorim are not more than one twenty-four thousandth of an inch in diameter, and if we suppose that the ova of infusoria and the spores of minute fungi are no more than one-tenth of the linear dimensions of the parent organism, there must be an incalcula ble amount of germs no larger than one two hundred-and-forty thousandth or one one-hun dred thousandth of an inch in diameter, which may appear in putrescible liquids, in' ar greater num bers than the germs in atmospheric dust, visible by the aid of the microscope, would lead us to expect. Schwann established the experimental proof that when air is first passed through an ignited tube, before coming in contact with the solutions of sugar, containing besides some nitrogenous substances, no fermentation is. excited. The same negative result is witnessed when the air is conducted through an apparatus filled with concentrated sulphuric acid (oil of vitriol) or even a strong solution of caustic pot ash, (Schulze) or even when filtered through cotton-wool, (Schroeder and Duscb). Dr. F.
Mohr makes some recommendations founded upon Schroeder's experiments, among which we will mention that the casks should be closed, after the wine has ceased fermenting, with a hung, through which passes an air-tight glass. tube filled with cotton-wool. Thus the air will be sifted of germs as it enters the cask upon the withdrawal of wine by the stop-cock. The fer mentation previous to that precaution is best con ducted in casks closed by means of a glass tube bent like an inverted letter U, one leg of which is inserted through the perforated bung, while the other dips into water placed in a vessel. By means of this arrangement all the carbonic acid liberated during the fermentation passes out through the water and can easily be watched, while the air is prevented from coming in contact with the liquid in the barrel. A layer of the heavier carbonic-acid gas on the surface of the liquor makes the exclusion still more complete and pre vents the gathering of mold (Pure du aim). though the cask be not full. Without such an arrangement it is impossible to prevent the access of air and spores through the invisible openings and fissures in the staves of the, casks. On the other hand a slow oxidation seems desirable, to separate nitrogenous matter and to ripen and improve young wines, whilst the develop ment of the bouquet in older wines seems. to be promoted by the exclusion of air or oxy gen. This gas, in fact, destroys it when brought in free contact with the wine. The germs being destroyed by heat, chemical agencies, or mechan ically removed from the air, no yeast fungi are formed. From these facts, Appert's method for preserving different kinds of food may find its explanation. Milk, meat, and vegetables are put into tin cans; these are placed in boiling water and immediately hermetically sealed. Liebig's explanation is that the trace of oxygen in the air that may still be present with the food is at once taken up by some parts of it without giving rise to the formation of ferment at this high tempera ture; while Schwann believes that by the destruc tive influence of the heat on the germs of fungi and infusoria, the food is preserved. Though the old theory of spontaneous generation, even when limited to some of the lowest orders of vegetable and animal life, is daily losing ground, and the omne vivem ex ow has become the axiom with naturalists, still there remain yet many unsettled points in connection with this matter, which require further investigation. Thus if we take it for granted that, according to Gay Lus sac's experiments, a few bubbles of oxygen gas obtained from chlorate of potassa at a high tem perature induce fermentation (when admitted to grape-juice surrounded by an atmosphere of hydrogen or carbonic acid,) it must be admitted that in this case any vegetable germs must have been excluded, provided that those already pres ent in the juice had been destroyed by boiling, and still fermentation took place ; and if this be so, were there no yeast plants present? It must also be remarked that in some of the experiments, where the results appeared to favor spontaneous.