578 On Reciprocal Linervation of Antagonistic Muscles. 
Excit. when the Inhib. component is weak, and more resembles the length 
under Inhib. when the Inhib. component is strong. This result on the 
muscle strikingly resembles in ratio the sensual result obtained by binocularly 
combining dark grey and light grey ea ae presented one to right 
eye the other to left. 
From the observations it seems clear that the reflex effect of concurrent 
stimulation of excitatory afferent nerve with inhibitory afferent nerve on 
the vasto-crureus nerve-muscle preparation is an algebraic summation of the 
effects obtainable from the two nerves singly, as v. Cyon has maintained for 
the heart. The individual effects of the two nerves “fuse to a resultant,” to 
use words applied by Meltzer to his results on the respiratory centre. One 
inference allowable from this is that in the case before us the two afferent 
ares employed act in opposite direction at one and the same point of applica- 
tion in the excitable apparatus. They are in this sense true antagonists. 
The inhibition exercised by the inhibitory member of the pair comes therefore 
under Heidenhain’s Class I of inhibitory reactions. As to the common locus 
of operation, the point of collision of the antagonistic influences, it seems 
permissible to suppose either that it lies at a synapse, in which case the 
opposed influences may be thought of as altering oppositely the permeability 
of the synaptic membrane, or that it hes in the substance of the “ central” 
portion of a neurone, probably of the motoneurone itself, meaning by “ central ” 
that part of the neurone which lies in the reflex centre. In either case the 
condition of the material of the common locus seems altered in two diametri- 
cally opposite ways by the two antagonistic afferent arcs. The net change 
which results there when the two arcs are stimulated concurrently is an 
aleebraic sum of the plus and minus effects producible separately by 
stimulating singly the two antagonistic nerves. 
[Reference was made above, p. 568, to observations on antagonism which 
took the vasomotor centre as test-object. On this subject a very clear statement 
is given by Bayliss.* “The results of exciting simultaneously the depressor 
nerve and a pressor nerve, such as the central end of the anterior crural, 
depend entirely on the relative strengths of the stimuli: whichever nerve is 
under the stronger excitation shows its own effect on the blood-pressure and 
when the excitation of this one is stopped the effect of the other manifests 
itself.” “There appears to be a perfect antagonism between the pressor and 
depressor actions on the centre.” In the same work, Prof. Bayliss describes 
also the result of opposing depressor action against asphyxial stimulation, 
the latter when weak lessening the effect oy the former, when strong 
annulling it—January, 1909.] 
* § Journ. of Physiology, vol. 14, p. 318, 1892. 
