Page:Life in Motion.djvu/189

Rh find the transverse section is the negative pole. This then is a demonstration of the electrical condition of the muscle at rest.

Now let us go a little farther. Leaving the muscle on the pads, with the longitudinal surface touching the pad on the left, and the transverse section touching the pad on the right, you notice the spot of light has taken up a position well towards the left. The spot will slowly move to the right as the muscle dies, but we need not wait for this. I need hardly say that a dead muscle gives no current. What would happen if we made the muscle contract? Would the contraction increase or diminish the current, or would it have no effect? To answer this question, I shall ask Mr. Brodie to lay the nerve still attached to the muscle over the wires coming from the induction coil, and, as he has a key in the circuit, I ask him by closing it to throw the muscle into tetanus while it remains on the pads. Observe once more the position of the spot of light. Tie now tetanises the muscle, and you see the spot immediately travels to the right, indicating either that the current is less during contraction than it was before, or