_Contrary Opinion. Life did not Originate on our Globe._—But all biologists do not share this opinion. Some, and not the least eminent, hold it to be an established fact that it is impossible for life to arise from a concurrence of inorganic materials and forces. This was the opinion of Ferdinand Cohn, the great botanist; of H. Richter, the Saxon physician, and of W. Preyer, a physiologist well known from his remarkable researches in biological chemistry. According to these scientists, life on the surface of the globe cannot have appeared as a result of the reactions of brute matter and the forces that continue to control it. According to F. Cohn and PI. Richter, life had no beginning on our planet. It was transported to the earth from another world, from the cosmic medium, under the form of cosmic germs, or _cosmozoa_, more or less comparable to the living cells with which we are acquainted. They may have made the journey either enclosed in meteorites, or floating in space in the form of cosmic dust. The theory in question has been presented in two forms:—_The Hypothesis of Meteoric Cosmozoa_, by a French writer, the Count de Salles-Guyon; and that of _cosmic panspermia_ brought forward in 1865 and 1872 by F. Cohn and H. Richter. _Hypothesis of the Cosmozoa._—The hypothesis of the cosmozoa, living particles, protoplasmic germs emanating from other worlds and reaching the earth by means of aerolites, is not so destitute of probability as one might at first suppose. Lord Kelvin and Helmholtz gave it the support of their high authority. Spectrum analysis shows in cometary nebulæ the four or five lines characteristic of hydro-carbons. Cosmic matter, therefore, contains compounds of carbon, substances that are especially typical of organic chemistry. Besides, carbon and a sort of humus have been found in several meteorites. To the objection that these aerolites are heated while passing through our atmosphere, Helmholtz replies that this elevation of temperature may be quite superficial and may allow micro-organisms to subsist in their interior. But other objections retain their force:—First, that of M. Verworn, who considers the hypothesis of cosmic germs as inconsistent with the laws of evolution; and that of L. Errera, who denies that the conditions necessary for life exist in interplanetary bodies. _Hypothesis of Cosmic Panspermia._—Du Bois-Reymond has given the name of _cosmic panspermia_ to a theory very similar to the preceding, formulated by F. Cohn in 1872. The first living germs arrived on our globe mingled with the cosmic dust that floats in space and falls slowly to the surface of the earth. L. Errera observes that if they escape by this gentle fall the dangerous heating of meteorites, they still remain exposed to the action of the photic rays, which is generally destructive to germs.