down in increased quantities, whereas cytoplastic metabolism, which produces more profound alteration in the living substance, and which goes so far as to bring about a breaking down and building up of the nitrogen containing atom groups, is hardly at all increased. It would be an error, however, to look upon these different kinds of metabolism as quite independent. Considering the close correlation which all the phases of metabolism bear to each other, this idea cannot well be entertained. If, however, we question in what manner, for instance, the functional and the cytoplastic metabolism are linked together, we have a problem before us which does not belong to the past, but to the present and future. Indeed, _Virchow_ seems already to have felt that a sharp division between the different phases and parts of functional metabolism in the cell does not exist, for he says: “It is true that it cannot be denied that, especially between the nutritive and formative processes and likewise between the functional and nutritive, intermediate gradations occur.” Still they differ essentially in their characteristic action and in the internal alterations which the stimulated part undergoes, depending on whether it functionates, nourishes itself, or is the seat of special growth. Disease consists of the influence of stimuli upon these physiological processes. The law of the specific energy of living substance is as clearly expressed in functional disease as it is in the physiological effects of stimuli. The pathological disturbance of function is purely quantitative, “nowhere is there a qualitative divergence.” The function exists or it does _not_ exist. If it is present, it is either strengthened or weakened. This gives the three fundamental forms of disturbance: absence, weakening and strengthening of the function. No function other than the physiological, even under the greatest pathological alterations, exists in any _structure_ of the body. “The muscle does _not_ perceive, the nerve moves no bone, the cartilage does not think.” In this way _Virchow_ rediscovered in the domain of pathology the law that his great teacher, _Johannes Müller_, had already clearly established in the field of physiology. But this law can no longer be applied to all pathological disturbances of the nutritive and formative activities of the cell. Here processes occur which do not consist of a quantitative change of the normal phenomena, but in the appearance of wholly foreign states, as in the case of amyloid degeneration or heteroplastic tumors. The question today and for the future arises, therefore, as to where the limits of the validity of the law of the specific energy of living substances are to be placed, a question closely connected with the other before mentioned, of the relations between functional and cytoplastic metabolism.