1912.] Innervation and Symmetrical Muscles. 221 



tion is seen to obtain in the reflex effect on the two muscles. The muscle 

 contralateral to the nerve exhibits excitatory contraction ; the ipsilateral 

 muscle inhibitory relaxation (fig. 1). This result holds good over a wide 

 range of intensities of stimulation of the afferent nerve. The contralateral 



Fig. I. Fig. 2. 



Fig. 1. — Keciprocal innervation of the extensor muscles, vastocmrei, of right and left 

 knee, first from left peroneal nerve, then from right peroneal. Decerebrate cat. 

 The inhibitory relaxations are in each case followed by post-inhibitory rebound. 



Fig. 2. — Extensor muscles, vastocrwei, of right and left knee. The right peroneal nerve 

 is first stimulated ; then the same nerve again, and during its stimulation left 

 . peroneal is stimulated with same intensity approximately as right, and the left 

 stimulus withdrawn, and finally the right. During the double stimulus both 

 muscles exhibit inhibitory relaxation. Decerebrate cat. 



excitation and the ipsilateral inhibitory relaxation increase pari passu as the 

 intensity of the stimulation is increased. 



But it is also possible experimentally to obtain simultaneous inhibitory 



R 2 



