In this highly technical monograph the author reports his laborious experiments on the electrophysiology of human muscles. New methods and apparatus had to be invented for this work, whereby the author believes that he has proved beyond doubt the proposition that a voluntary contraction of muscles is caused by the dispatch of fifty impulses per second to the contracting muscle and that each of those impulses causes a distinct contraction-wave. This he has been able to prove by causing irritation of the motor nerve fifty times per second and observing as a consequence a muscular effect not distinguishable from natural contraction. In no other way has he succeeded in reproducing the mammalian muscle contraction, though he has experimented with high-frequency currents, cathodal-closure tetanus, stimulation with different electrical time-stimuli and strychnin-tetanus. We trust that some practical application in medicine may come from these interesting experiments.