1908.] Innervation of Antagonistic. Muscles. 573 
- If the intensities of the reflex inhibition and the reflex excitation 
respectively be represented by the numbers on the Kronecker scale attached 
to the stimuli of their respective nerves, the combination Inhibition 100+ 
Excitation 500 (fig. 2) gives a lesser grade of contraction than the combination 
Inhibition 75+ Excitation 500 (fig. 3). Further, in the former combination 
(fig. 2) the grade of contraction is nearer to the degree of relaxed state 
under the inhibitory stimulus alone, and is further from the degree of con- 
traction under the excitatory stimulus alone than in the latter (fig. 3) 
combination. 
If figs. 2 and 3 are compared with fig. 1, they elucidate certain features of 
the last-named. In fig. 1, during the stimulation of the inhibitory afferent 
nerve (upper signal) by 80 Kronecker units, there was added stimulation of 
the excitatory afferent nerve (lower signal) by 400 Kronecker units. Marked 
contraction of the muscle resulted, and was maintained, although with gradual 
decrease, as long as the stimulation of the excitatory afferent nerve continued. 
The stimulation of the excitatory afferent nerve was then discontinued, and 
the muscle at once relaxed to the length it exhibited immediately before 
the advent of the excitatory reflex. Finally, the inhibitory stimulus was 
withdrawn. | 
From this record and from others similarly obtained the inference might 
be drawn that the excitatory reflex in producing the contraction entirely 
obliterated the action of the antagonistic inhibitory are stimulated at the same 
time. Such records as figs. 2 and 3 show, however, that that was certainly not 
the case. On the contraction of the muscle in fig. 1, the action of the inhibi- 
tory afferent nerve is without doubt exerting influence all the time, and 
makes the amplitude of the contraction less than it otherwise would be. 
The contraction obtained is a compromise between the two antagonistic 
influences of excitation and inhibition simultaneously at work. The quick 
subsidence of the contraction on discontinuance of the stimulus of the exci- 
tatory afferent nerve in fig. 1, as compared with its slow disappearance in 
figs. 2 and 3, is further evidence of the continued operation of the inhibitory 
action in the former. 
In the type of experiment exemplified by figs. 2 and 3, the period of 
simultaneous stimulation of the two nerves of opposed effect followed 
immediately on the inhibitory reflex already in operation under stimulation 
of the inhibitory member of the opposed pair. If the result thus given by 
the concurrent stimulation of the opposed pair be really of general applica- 
tion to their case, it should appear also when the sequence of their stimulation 
is reversed. The reversal was arranged, and the results it gives are exempli- 
fied by the records shown in figs. 4, B and 5, B. 
