262 Prof. C. S. Sherrington. Reciprocal [Mar. 25, 



flg. 9a, opens with stimulation of the ipselateral afferent. This causes con- 

 traction of the flexor and, at the same time, relaxation of the extensor. Some- 



Fig. 10. — Beflex contraction of Semitendiuosus, Fl, and Vastocrureus, Et, recorded with 

 double-nryograph. The lever attached to vastocrureus (Et) writes not directly below 

 but about a centimetre to the right of that attached to semitendiuosus (Fl) ; control 

 arcs, cut when the recording surface was not moving, indicate the moment of 

 commencement of stimulus on each myogram line. The ipselateral peroneal nerve 

 (afferent end) is stimulated as shown by the lower signal line Fl', and causes contrac- 

 tion of semitendinosus and relaxation of vastocrureus. Then follows stimulation of 

 contralateral peroneal nerve as shown by the upper signal Et'. This combined 

 stimulation lessens, but not to extinction, the contraction of semitendinosus and at 

 the same time brings into contraction the antagonistic muscle, vastocrureus. On 

 reverting to the single stimulation again, the contraction of semitendinosus increases 

 once more and that of vastocrureus disappears. Finally, on cessation of the single 

 stimulation Fl', a rebound, r, from inhibitory relaxation to increased tonic contraction 

 occurs in vastocrureus synchronously with the relaxation of the flexor. Time above 

 iu seconds. Decerebrate cat. 



what more than a second later stimulation of the contralateral afferent was 

 commenced, the stimulation of the ipselateral afferent continuing unaltered. 



