The present study arose from the observation that the knee jerk could be elicited by striking the inferior edge of the patella from below upward. Since this method of stimulation appears to shorten rather than to stretch the quadriceps, the question arises whether the knee jerk as elicited clinically does not contain other elements in addition to the stretch reflex. Such a possibility is further suggested by the sensation in the region of the subpatellar bursa associated with the patellar reflex.
METHOD
The method employed was copied from the isometric technic developed by Sherrington. Cats were decerebrated by the trephine method, usually after the preparation had been completed under ether anesthesia. The left hind leg was immobilized by section of all muscles inserting in the region of the great trochanter down to and including the quadratus femoris, section of the sciatic nerve, the nerve to the hamstrings, the anterior crural