alterations of protoplasm resulting from the application of stronger doses of the narcotic can scarcely be explained as simply the result of a mere decrease of the oxydative processes. They would seem to consist rather, as suggested by _Binz_, as coagulation, in an alteration of the state of certain components of living substance. Whether these alterations are already present in a correspondingly slight amount in those degrees of narcosis after which complete recovery can take place and further whether in this case they are in any way concerned in bringing about the individual symptoms of the former, are questions the decision of which must be left to future investigations. _Höber_[223] indeed makes such an alteration of the colloidal state of the lipoid the basis of a theory of narcosis. But such assumptions are scarcely more than speculations. This is one of the points in which our present knowledge is lacking. [222] _Binz_: “Vorlesungen über Pharmakologie für Aerzte und Studierende.” II Aufl. Berlin 1891. [223] _Höber_: “Beiträge zur physikalischen Chemie der Erregung und der Narkose.” Pflügers Arch. Bd. 120, 1907. The same: “Die physikalisch-chemischen Vorgänge der Erregung.” Sammelreferat. Zeitschr. f. allgem. Physiol. Bd. X, 1910. Even if we restrict ourselves to the actually established alterations produced by the narcotic in living substance, new problems present themselves, the investigation of which requires further effort. Above all, the question arises as to the finer mechanism of oxydative depression. In what manner does the narcotic molecule, entering into the living substance, suppress the oxydative processes? Here there are very different possibilities to be taken into consideration and up to the present in our investigations of a suppression of the oxydative processes resulting from narcosis, we have stood on the firm ground of assured facts. However, the discussion of the nature of this suppression leads us into the domain of _hypothesis_. But without hypothesis there can be no progress in knowledge. In all branches of scientific research, working hypotheses are required for the obtainment of new facts. On closer reflection, there are chiefly _three_ possibilities, which, considered from the standpoint of our present knowledge of the processes in living substance, offer an explanation of the oxydative suppression as a result of narcosis.