This has been expected from experiments on human beings, such experiments as Tesla’s and those of d’Arsonval. But an entire animal is not at all a satisfactory instrument wherewith to attack the question; its nerves are so embedded in conducting tissues that it may easily be doubted whether the alternating type of stimulus ever reaches them at all. By dissecting out a nerve and muscle from a deceased frog after the historic manner of physiologists, and applying the stimulus direct to the nerve, at the same time as some other well known ¹/₁₀₀th a volt stimulus is applied to another part of the same nerve further from the muscle, it can be shown that rapid electric alternations, if entirely unaccompanied by static charge or by resultant algebraic electric transmission, evoke no excitatory response until they are so violent as to give rise to secondary effects such as heat or mechanical shock. Yet, notwithstanding this inaction, they gradually and slowly exert a paralysing or obstructive action on the portion of the nerve to which they are applied, so that the nerve impulse excited by the feeble just perceptible ¹/₁₀₀th-volts stimulus above is gradually throttled on its way down to the muscle, and remains so throttled for a time varying from a few minutes to an hour after the cessation of the violence. [I did not show this experiment at the lecture.] _Air Gap and Electroscope charged by Glass Rod and discharged by the Wave Impulse from a moderately distant Sphere excited by Coil._ [Illustration: FIG. 16.--Air gap for Electroscope. Natural size. The bottom plate is connected to, and represents, the cap of an electroscope; the “knob” above it, mentioned in text, is the polished end of the screw, whose terminal is connected with the case of the instrument or “earth.” The electroscope being charged to the verge of overflow, the impact of weak electric waves collected by a bit of wire sticking up from the left-hand binding screw precipitates the collapse of the leaves.]