On the myogram of the flexor-reflex evoked by a single break-shock

Our object has been to compare the reflex contraction of a muscle when evoked by a single induction shock with the contraction evoked from the same muscle when a similar stimulus is applied directly to the muscle’s motor nerve. The experiments extend some observations previously reported in these Proceedings (2) and in the ' Journ. of Physiology’ (6). The literature of the subject was given in those papers and for it reference may be had to them.Method . The reflex preparation employed has been the spinal cat, the muscle being tibialis anticus. Either before or after the spinal cord had been transected the animal was decerebrated. The spinal transection and the decerebration were performed under deep anæsthesia. The spinal transection was in some cases made three to ten days prior to the decerebration. The seat of spinal transection was usually at the posterior end of the thoracic region, but sometimes at the anterior end of the cervical region. All the hind-limb muscles except tibialis anticus were immobilised by nerve section, or in the case of extensores, digitorum and peronei, tenotomy. The limb was fixed by steel drills in tibia and femur, the drills being clamped to unyielding uprights on the experimental table. The tendon of tibialis anticus was attached by a short length of waxed fishing line to an isometric myograph of the torsionwire pattern. The vibration period of this recorder was somewhat less than 0.01". The afferent nerves of the limb were severed and those used for stimulation were popliteal in the ham, musculo-cutaneous on the dorsum of the foot, and internal saphenous, femoralis, and external cutaneous below the groin.