564 On Reciprocal Innervation of Antagonistic Muscles. 
Fie. 3.—Crossed reflexes produced in vasto-crureus by faradic excitation of the proximal 
stump of the cut popliteal nerve of opposite limb. Time in seconds above : below is 
signal line giving duration of the faradic stimulus. The intensity of the stimulus 
is the same for A and for B. A is the reflex contraction of the left vasto-crureus, 
B that of the right ; the spinal afferent roots containing the afferent fibres of the 
right vasto-crureus nerve had been cut 42 days previous to decerebration and 
examination of the reflexes. In B the tonic after-continuance of the reflex is 
wanting ; on cessation of the stimulus the muscle at once relaxes completely and 
its slackness is indicated by the vibratory swing at its return to the base-line. In 
A, on cessation of the stimulus, a tonic after-contraction similar to that of the 
“shortening reaction” succeeds the contraction caused by the exciting stimulus 
itself. This was allowed to continue for 8 secs, and then the recording surface 
was stopped and the muscle was (Z.r.) forcibly stretched by hand to about the 
length it had at first before the reflex and then released ; the recording surface 
was then started again and the lever traced a horizontal line at the original level, 
showing that the “lengthening reaction ” (Z.r.) had taken place. 
In order to make the comparison fair in regard to intensity of faradic stimulus 
the distance between the electrodes was in both cases the same, z.e., 5 mm., and 
the nerve-trunk was drawn between the poles; the distance of the secondary 
spiral from the primary was the same for both stimulations, and a 100,000 ohms 
resistance was in the secondary circuit. The duration of the stimulus was 
managed by hand and was longer in A than in B; that difference does not account 
for the difference in the duration of the two reflexes, Time marked above in 
seconds. 
Fic. 4.—Crossed reflexes produced in vasto-crureus by mechanical excitation (quick 
tightening of a previously loose thread-loop) of proximal end of cut anterior 
tibial nerve of opposite limb. A shows the reflex response given by left vasto- 
crureus muscle to this excitation of right anterior tibial nerve. B shows the 
response given by right vasto-crureus to the similar stimulations of left anterior 
tibial nerve. Both reactions are from the same animal and within four minutes’ 
interval one from the other. The spinal afferent roots containing the afferent 
fibres of the right vasto-crureus nerve had been severed 52 days prior to the 
experiment. The tonic maintenance of the reflex, which in the case of the left 
(A) vasto-crureus lasted with little abatement for a couple of minutes, is absent 
in the reflex given by the right vasto-crureus (B). Time marked above in seconds. 
Fie. 5.—Crossed reflexes produced in (A) the left vasto-crureus and in (B) the right 
vasto-crureus by stimulation of the popliteal nerve. Stimulation by a series of 
weak break shocks, marked by the lowest signal. The stimuli are admitted to the 
nerve for the period during which the short-circuit key in secondary circuit is open, 
marked by the upper signal line. The afferent nerve-fibres of the right muscle (B) 
had been severed 80 days previously; those of the left muscle intact. Time 
above in seconds. 
