rest on the same basis.” And different it could not be, reasons Büchner, since life knows no exceptions, does not shirk any inorganic forces, but is itself only the result of the activity of these forces. To obtain a definite understanding of the origin of life it is therefore sufficient to examine the origin of organic matter in our days, and for such an analysis there is at least no lack of material. Wherever a tree or a grass blade grows or a seed sprouts there dead substance is transformed into living; wherever an animal or a plant is decaying, there organic matter is again turned into inorganic. The result obtained through such investigations already made, stood in direct opposition to the immediate observations. Although Harvey’s formula finally was accepted, it was nevertheless taught _that no specific life-force exists_. This contradiction was never fully understood or emphasized during the last century, and the reason was that the materialistic tendency was so predominant that nobody noticed that the question of life-force is the innermost main point, around which not only _generatio spontanea_ and _omne vivum ex vivo_, but also their consequences, materialism and idealism, are centered. But in order to deny life-force as an independent principle, some scientific facts to build upon were necessary and these were not lacking. Before we state these facts we will in a few words describe the historical situation. According to the previously prevailing vitalistic doctrine a specific life-force existed, present and active in all organic processes. The conceptions in regard to these processes were, however, very dim, and the reason was that the problem of combustion had not yet been solved. This problem may be said to be the very key to the chemical explanation of an organism. The ancient mystery of fire was first solved by Lavoisier after Scheele and Priestly had discovered oxygen. The solution of this complicated question not only became the starting point for a new and rapid evolution of chemistry, it also almost immediately threw a clear light on the innermost recesses of the organism. The elementary constituents of the organism and their origin were known before, and it now became also possible to explain the great store of energy that the living being possesses. To assume a specific life-force seemed superfluous. Life-force, from having been the indispensable explanation of organic phenomena, commenced more and more to be regarded as a “back-way for ignorance,” one “of those many side doors that dull heads employ when they find it too laborious to think about something that they do not understand.”