1911.] 



On Reflex Inhibition of the Knee Flexor. 



205 



Fig. 3. — Influence of intensity of background-reflex on effect of intercurrent reflex. Semi- 

 tendinosus (cat, decerebrate). Lower signal marks stimulation (faradic) of ipsilateral 

 afferent (peroneal + popliteal). This stimulus in b and d is 60 Kronecker units ; in a and c 

 it is weaker, namely, 30 Kronecker units. Upper signal marks stimulation (faradic) of 

 contralateral afferent, and is of the same intensity, namely, secondary coil at 20 cm. for 

 observations a, b and c, but for d it is stronger, namely, coil at 14 cm. In a and c the 

 effect of the intercurrent stimulus is inhibitory, in b it is pressor, i.e. augmentative of 

 contraction ; in d it is pressor also, but the increased contraction is followed by inhibition. 

 Time above, in seconds. 



ii. Influence of the Background Contraction on the Effect obtainable from the 



Intercurrent Contralateral Stimulus. 

 It was shown in a previous communication that when two afferent nerves 

 with mutually opposed influence on the same muscle are stimulated con- 

 currently the effect on the muscle is an algebraic summation of the 

 contraction and inhibition belonging to the two nerves respectively. Some 

 of the examples then cited were furnished by the same muscle, semi- 

 tendinosus, and the same afferents as chiefly employed in the present 

 observations, and the present observations have confirmed the foregoing. 

 They have also extended them in the following respect : Suppose a weak 

 contralateral stimulus is chosen, such that it produces slight inhibition of a 



