generation a mercurial bath was made use of, to isolate the substances experimented upon. Pas teur has since ascertained that mercury taken from the bath of any laboratory is itself loaded with organic germs. He likewise found that the contact of the atmospheric air with a fermenting liquor is primarily indispensable, only as being a vehicle for the germs of the various ferments. Vegetable organisms frequently collect as mold in saline solutions, and decompose them; also even in dilute sulphuric acid. They have never as yet been observed in solutions of chromic acid and ehromates, whence these answer well for preserving brains and other highly albuminous anatomical preparations. A solution of tartaric acid will, even when left in tight glass-stoppered bottles, soon become turbid, and lose its acid taste. A microscopic examination will always trace the cause to a formation of mold which feeds upon the acid. The so-called vinegar plant is a vegetable organism, and acts as a ferment when brought into dilute alcohol. Some mineral waters containing free sulphuric acid, and tasting strongly sour, are filled with vege table mold. Thermal springs of a very high temperature are not exempt from vegetable productions. Even in poisonous liquids con taining arsenic, etc., we find some species of fungi which flourish and multiply. Ehrenberg, the distinguished Prussian naturalist, who has devoted the greater part of his life to the study of infusorial life, is opposed to a generatio equivoca, and believes that inf usorke are developed from eggs. He has described about eight hun dred living species of these microscopic animals, which swarm almost everywhere. They abound in countless numbers even in the fluids of living and healthy animals. Owing to the extreme lightness of these beings we must not be sur prised to learn of their transportation by storms over whole seas and continents. Ehrenberg believes that the baccilarke found upon some steeples at Berlin came originally from South America. In the Alps there is sometimes found
a snow of a blood-red color; it has beeh ascer tained that this coloring matter is composed chiefly of a one-celled plant (Protococeus nivalis) of the tribe alrfi e; and, what is most singular, when the snow has been melted for a short time so as to become a little warmer than the freez ing point, these beings die because they can not endure so much heat! The effect of antiseptics in arresting fermentation may be differently explained according as we favor Liebig's or Schwann's theory. The former assumes that corrosive sublimate, arsenic, and creosote, unit ing with the ferment, prevent the decomposition of it, and, in consequence, that of other organic bodies with which it is in contact. Schwann believes that these substances, acting as poisons, destroy the life of the previously described organisms, and that hence the metamorphosis of vegetable substances is arrested by them. We must acknowledge that, notwithstanding the voluminous writings regarding the origin of many of the lowest forms of animal and vege table life, it is yet a mystery, and that here fancy has as great scope as ever. The spontaneous change of azotized organic matter called putre faction is most closely allied to the process of fermentation, being mainly characterized by the evolution of gases of a disagreeable odor, as ammonia, and sulphuretted and phosphoretted hydrogen. For this transposition of elements, moisture, and contact with air, are in the first instance indispensable. It was believed that the animalculte making their appearance in putres cent substances constituted the primary agent or cause of decomposition; and even if more recent investigations have modified this view, it must be admitted that these minute animals hasten and intensify the resolution of the elements.