Observations on ipsilateral contraction and “inhibitory” rhythm

Abstract
The following observations on the reflex activities of the vastocrureus muscle in the decerebrate cat have been made by combining, on the same photographic plate, records from a string galvanometer and from a high-frequency isometric myograph. Both methods of investigation have been used separately by numerous workers (1, 2, 3, 4, 5, 9, 10, 11, 13, 14, 16, 21, 22, 23, 25, 28), but it seemed desirable to combine these methods as has been done recently by one of us (18).Method.—The isometric myograph employed (which has been previously described) had a natural frequency of 1,600 per second. Its shadow together with the real image of the string were focussed on the camera by a lens. They were thus both in the same optical system. Silver-chloride electrodes were used as leads, one being inserted into the tendon, the other into the belly of rectus through a “ window ” made in the skin and sartorius muscle. Sometimes the rectus muscle was dissected away from its fellow muscles in quadriceps and exposed. This eliminated the possibility of bits of skin and fascia touching the proximal lead during the contraction, which was occasionally troublesome, but it had the disadvantage of subjecting the muscle to undue exposure, with resulting deterioration. The stimuli were usually monophasic break-shocks delivered from a Sherrington torsion-wire key. Occasionally double shocks were used, as noted in the legends to the figures. Cats decerebrated under deep anæsthesia by the trephine method were used throughout. To increase the sensitivity, the galvanometer string was made somewhat slack, the tension usually employed being 8 to 11 mm. per m. v. at a magnification of 285.

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