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30 gives one a very inadequate notion of the amount of energy that can be brought into play by a small muscle like the one we are now studying. Here is another muscle of the same size. It weighs about half a gramme, or about seven grains. We have suspended it so that

when it contracts it lifts a lever, and, breaking an electric circuit, causes a bell to ring. This apparatus, I may mention, was sent to me for these lectures by Professor du Bois Reymond of Berlin, who lectured on "Nerve and Muscle"