That organic change in matter is the most universal and distinctive evidence of life has been declared by physiological chemists and chemical physiologists times without number during the last thirty years and their utterances are translated by Herr Duehring into his own clear and elegant language. But to define life as an organic change of matter is simply to define life as life, for organic change of matter, or change of matter with plastic creative arrangement is a statement which must itself be explained by life, and the explanation in its turn by the difference between organic and inorganic, that is between that which is alive and that which is not alive. So that with this explanation we do not get at the problem. Organic change, as such, is frequently found where life does not exist. There are whole series of processes in chemistry, which by the proper combination of the elements, produce again their own conditions, so that thereby a certain body is the creator of a process. Thus in the manufacture of sulphuric acid by the burning of sulphur, there is created in this process sulphuric dioxide SO_{2}, and if one add steam and nitric acid thereto, the sulphuric dioxide takes up the water and the oxygen and becomes H_{2} SO_{4}. Nitric acid gives off oxygen and becomes nitric oxide, this nitric oxide simultaneously takes up new oxygen from the atmosphere and is transformed into a higher oxide of nitrogen and from this acid sulphuric dioxide is again given off and made by the same process, so that, theoretically, an infinitely small amount of nitric acid should be effective to transform an unlimited quantity of sulphuric dioxide, oxygen and water into sulphuric acid. Change in matter regularly occurs through the passing of fluids through dead organic and inorganic membranes as in the artificial cells of Traube. It therefore appears that there is no progress by the way of organic change for the quality of organic change which was to explain life must itself be explained by life. We must therefore seek it elsewhere. Life is a mode of existence of protoplasm and consists essentially in the constant renewal of the chemical constituents of this substance. Protoplasm is here understood in the modern chemical sense and comprises under this name all substances analogous to the white of an egg, otherwise called protein substances. The name is not satisfactory, for the ordinary white of egg plays the least active role of all transformed substances, since it only serves as mere nourishment for the yolk, for the self-developing germ. As long however as so little is known of the chemical constituents of protoplasm the name is better than any other because more inclusive.