If a nerve of a nerve muscle preparation is drawn through a specially devised glass chamber so that the middle portion can be narcotized or asphyxiated and the nerve so arranged that it rests upon a pair of electrodes in the chamber and upon a second pair without the chamber and centrally located, then the nerve can be narcotized or asphyxiated and thereby the alterations in the irritability as well as the conductivity can be followed. In order to obtain as distinct a picture of this alteration as possible, I tested continuously the threshold of stimulation, which just produced minimal contraction in the muscle, and _Fröhlich_[111] continued these observations. As a result the following very remarkable conditions were observed. During the increase of the depth of narcosis or asphyxia the irritability sinks more and more with regularity. The conductivity remains unaltered for a long time, as the strength of the threshold stimulus is not changed until irritability has fallen to a definite point. When this is reached, conductivity disappears. (Figure 24.) The most important point in this connection, however, is, that the conductivity disappears simultaneously and practically momentarily for the excitation produced by both weak and strong stimuli. When the stimulation at the electrode placed centrally to the chamber does not bring about response for threshold stimuli, maximal stimuli at the same time also become inoperative. This is a very interesting point, the importance of which has not until now been recognized. This fact is not in harmony with the view held until now, that in the nerve fiber different strengths of stimuli bring about excitation of different intensity, and are then conducted. Let us now clearly comprehend this problem. [111] _Fröhlich_: “Erregbarkeit und Leitfähigkeit des Nerven.” Zeitschr. f. allgem. Physiologie, Bd. III, 1904. [Illustration: Fig. 24. Curves of the changes in irritability (p) and conductivity (c) of a nerve under the influence of narcosis or asphyxiation. (After _Fröhlich_.)]