segmented infusoria of an entirely new type. Its length varied from the 1/150 to 1/100 of an inch, each ring was ciliated, and the whole series of cilia extending along the body acted in concert; a circlet of them surrounded the anterior segment; a canal seemed to extend throughout the body. It was propagated by bisection; the two parts remained attached to one another; an independent ciliary motion was observed in each which did not interfere with the motion of the whole. It was supposed to be a larval form or series of forms. Mr. Samuelson’s observations show, that the atmosphere in all the great divisions of the globe is charged with representatives of the three kingdoms of nature, animal, vegetable, and mineral: that the animal germs not only include the obscure types of monads, vibrios, and Bacteria, but also the Glaucoma, Cyclides, Vorticella, and other superior Infusoriæ, and occasionally though very rarely germs of the Nematode worms. It has been already mentioned that many of the microscopic fungi are ferments, aiding greatly in the decomposition of organic matter. They however are by no means the only agents in decomposition. The moment life is extinct in an animal or vegetable, Infusoria of the lowest grade seize upon the inanimate substance, speedily release its atoms from their organic bond, and restore them to the inorganic world whence they came. The ferment which transforms lactic acid into butyric acid is a species of vibrio which abounds in the liquid, isolated or united in chains; they glide, pirouette, undulate, and float in all directions, and multiply by spontaneous division. Vibrios possess the unprecedented property of living and propagating without an atom of free oxygen; they not only live without air, but air kills them. This singular property forms an essential difference between the Vibrios and the Mycoderms: the former cannot live in oxygen; the latter cannot live without it, and as soon as it is exhausted within the infusion, they go to the surface to borrow it from the atmosphere.