D3 
On Reciprocal Innervation of Antagonistic Muscles. Eleventh 
Note.—Further Observations on Successive Induction. 
By C. 8. SHERRINGTON, D.Sc., F.R.S. 
(Received November 4,—Read December 5, 1907.) 
(Physiology Laboratory, University of Liverpool.) 
? 
It was shown in previous notes* of this series that in the “ flexion-reflex< ’ 
of the limb the reflex inhibition of the extensor muscles is frequently 
followed by contraction of them. This contraction ensues immediately on 
cessation of the inhibitory stimulus, and is often more accentuated than was 
the contraction originally inhibited. The phenomenon was ascribed to a 
process of rebound in the central part of the nervous are inhibited, and 
this process, on account of its seeming analogy with certain visual phenomena 
often called “ inductive,’ was termed “successive induction.” 
The occurrence of this ‘‘ successive induction ” made it seem probable that 
under favourable conditions the reflex evoked in the limb by a single 
stimulus would be diphasic with a first phase of flexion followed by a subse- 
quent phase of extension. The following observations show that this is in 
fact the case, and under appropriate conditions regularly so. 
Among conditions requisite for the reflex’s exhibition of this .diphasic 
character is freedom of the preparation as far as possible from such 
depressing influences as “shock,” deep narcosis, fatigue, etc. In purely 
spinal reflexes successive induction does occur; thus, it causes exaltation 
of activity of the extensor arcs to ensue after their inhibition during a 
flexion reflex; that was established by observations previously reported.t 
In those observations the reflex preparation used had been preserved over 
long periods subsequent to spinal transection, the depression due to spinal 
shock in the ordinary meaning of the term had had prolonged opportunity 
to subside. In the present observations the examination of the reflex has 
been proceeded to within a few hours of the transection, since it was found 
that the successive induction could be observed without recourse to long 
periods of recovery if the transection instead of being spinal was pontine, 
vc, through the gnterior part of the hindbrain. The transection and 
* * Roy. Soc. Proc.,’ B, vol. 76, p. 160; vol. 77, p. 478; vol. 79, p. 347; also ‘ Inte- 
grative Action of the Nervous System,’ London and New York, pp. 21, 206, 1906. 
+ Sherrington, ‘Roy. Soc. Proc.,’ B, vol. 76, p. 161; vol. 77, p. 478; ‘Integrative 
Action of the Nervous System,’ p. 19 ; also article “Spinal Cord,” Schafer’s ‘ Text-book of 
Physiology,’ vol. 2, p. 841, 1900. 
