Neither the process of autogeny, nor that of plasmogeny, has yet been directly observed with perfect certainty. In early, and also in more recent times, numerous and interesting experiments have been made as to the possibility or reality of spontaneous generation. Almost all these experiments refer not to autogeny, but to plasmogeny, to the origin of an organism out of already formed organic matter. It is evident, however, that this latter process is only of subordinate interest for our history of creation. It is much more important for us to solve the question, “Is there such a thing as autogeny? Is it possible that an organism can arise, not out of pre-existing organic, but out of purely inorganic, matter?” Hence we can quietly lay aside all the numerous experiments which refer only to plasmogeny, which have been carried on very zealously during the last ten years, and which for the most part have had a negative result. For even supposing that the reality of plasmogeny were strictly proved, still autogeny would not be explained by it. The experiments on autogeny have likewise as yet furnished no certain and positive result. Yet we must at the outset most distinctly protest against the notion that these experiments have proved the impossibility of spontaneous generation in general. Most naturalists who have endeavoured to decide this question experimentally, and who, after having employed all possible precautionary measures, under well-ascertained conditions, have seen no organisms come into being, have straightway made the assertion, on the ground of these negative results: “That it is altogether impossible for organisms to come into existence by themselves without parental generation.” This hasty and inconsiderate assertion they have supported by the negative results of their experiments, which, after all, could prove nothing except that, under these or those highly artificial circumstances created by the experimenters themselves, no organism was developed. From these experiments, which have been for the most part made under the most unnatural conditions, and in a highly artificial manner, we can by no means draw the conclusion that spontaneous generation in general is impossible. The impossibility of such a process can, in fact, never be proved. For how can we know that in remote primæval times there did not exist conditions quite different from those at present obtaining, and which may have rendered spontaneous generation possible? Indeed, we can even positively and with full assurance maintain that the general conditions of life in primæval times must have been entirely different from those of the present time. Think only of the fact that the enormous masses of carbon which we now find deposited in the primary coal mountains were first reduced to a solid form by the action of vegetable life, and are the compressed and condensed remains of innumerable vegetable substances, which have accumulated in the course of many millions of years.