None deny that rigidity of the limbs can be effected mesmerically; but all mistake who impute the phenomenon to muscular ability, irritability, or energy. All flesh is inert; all muscular fibrine is flexible, bends from its own weight when held horizontally, and over it the will has neither power nor influence. Then, how is a muscle or nerve to stiffen itself, and where is the mechanical arrangement within for such purpose? The power is derived from without, and consists in medium of space. The de-electrising passes make entrance-room for influent medium of space, which is the cause of the limbs becoming rigid. As in Bramah's pump, water serves the purpose of an iron piston, so, within the nerves and muscles, medium of space in excess and under the general pressure, is an equally rigid piston, and the cause of all muscular strength and of rigidity. The depolarizing passes bring back electric matter, which displaces all excess of medium of space, and with it the physical cause of rigidity.