If I here speak only specifically of the conduction of excitation instead of the conductivity of response to stimulation this is not only primarily for the reason that we intend especially to analyze the conductivity of excitation on this occasion, but also because no other effects of stimulation except those of excitation can be conducted from the part affected by the stimulus to the surroundings. Although considered on theoretical grounds it appears more or less improbable that depression is extended from the place of its origin, it is very easy to convince one’s self experimentally of the fact that depression following a stimulus is invariably localized to that portion directly affected by the stimulus. The nerve furnishes a very favorable object for this purpose. If a nerve muscle preparation of the frog is made and introduced in the glass chamber previously described containing platinum electrodes, and another pair is applied to the nerve between the chamber and the muscle, it is possible to subject the stretch of nerve in the chamber to various agents, producing a paralyzing effect. In this way it may be exposed to an atmosphere of pure nitrogen for example, or to narcosis as by ether, chloroform, carbon dioxide and other gases, to an increase in temperature or to other agents, without these in any way affecting the irritability of the nerve stretch situated over the electrode between the chamber and the muscle. The contractions of the muscle, which are produced by stimulation of the periphery region of the nerve with stimuli of a definite strength, remain unaltered, even when the asphyxiated stretch of nerve in the chamber is already completely degenerated. The central depression of a ganglion cell of a motory neuron is likewise wholly without influence on the degree of excitability of its nerve fiber, as I was able to demonstrate[79] in the reflex inhibition of the motor neurons of the spinal cord of the dog. (Figure 14.) That which is conducted by the nerves is solely the process of excitation. [79] _Max Verworn_: “Zur Physiologie der nervösen Hemmungserscheinungen.” Arch. f. Anat. u. Physiol. physiol. Abt. Suppl. 1900.