It also appears from this experiment that the
note of about 36 vibrations per second heard on
auscultating a contracting muscle is not the
fundamental tone itself, but the first overtone
of the muscle sound.
5. The pitch of the sound heard when a
muscle is thrown into tetanus by stimulating
the spinal cord is to a considerable extent in-
dependent of the rate of stimulation.
Lengthen the vibrating reed used in Experi-
ment 4 by moving it out from the jaws of the
clamp, so that the reed shall vibrate about 10
times per second.
Expose the vertebral column in a frog the brain
of which has been destroyed (page 132). Strip
the skin from, one leg. Free the lower end of the
gastrocnemius muscle by severing the tendon.
Eaise the muscle so that it may be attached to
the under side of the vibrating reed mentioned
in Experiment 4, but be careful not to injure
the nerve. Insert needle electrodes between
the vertebras and connect them with the secon-
dary coil of an inductorium arranged for teta-
nizing currents (posts 2 and 3). Stimulate the
muscle.
THE CHANGE IN FOKM 215

The reed will again be thrown into sympa-
thetic vibration, although the number of stimuli
is about 100 per second.
With the aid of the interrupter described in
Experiment 4 stimulate the spinal cord at the
rate of 18 per second.
The vibrations during tetanus will be stronger.
