68 Prof. C. 8. Sherrington. On Reciprocal [ Nov. 4, 
YYW WY YAY WWW 
VV 
in the primary circuit by introducing 40 ohms 
additional resistance. The upper record (A) 
in the figure shows the reflex effect of faradisa- 
tion of the afferent nerve with the secondary 
coil at 40 units of the Kronecker scale, and 
with the 40 additional ohms in the primary © 
circuit. The effect is seen to be reflex 
inhibition, as is evidenced by a slight yet 
distinct relaxation of the vasto-crureus muscle. 
The stimulus was, therefore, above threshold 
value for producing reflex inhibition of the 
extensor arc. The lower figure opens with the 
effect of faradisation of the same nerve a 
minute later with the secondary coil unaltered 
in position (ze, 40 Kronecker units), but 
without the inclusion of the 40 additional 
ohms in the primary circuit. This stronger 
stimulus is seen to produce smart reflex 
relaxation of the extensor muscle. When 
that has reached its full amplitude and 
endured for something over a second, the extra 
40 ohms are abruptly introduced (by un-short- 
circuiting them) into the primary circuit, and 
the faradic stimulus is thus reduced to the 
intensity it had in the upper trace of the 
figure, 4¢., to an intensity near, but distinctly 
above, threshold value under the experimental 
conditions of a minute before. The record 
shows that those conditions have now under- 
gone a change, for now, instead of a weak 
inhibition, a strong extensor contraction sets 
in. This is the rebound contraction, and the 
change that has altered the conditions has 
been “successive induction” in the reflex 
preparation. The rebound contraction exceeds 
in intensity that obtaining prior to the inset 
of the original inhibition. The duration of 
the less intense faradisation, marked by the 
upper signal line, is continued for about a 
second, and then by short-circuiting the 
