965 
Reciprocal Innervation of Antagonistic Muscles. Thirteenth 
Note.—On the Antagonism between Reflex Inhibition and 
Reflex Excitation. 
By C. S. SHERRINGTON, D.Sc., F.R.S. 
(Received November 3,—Read December 10, 1908.) 
(From the Physiology Laboratory, University of Liverpool.) 
In further prosecution of observations made in Ludwig’s laboratory by 
Schmiedeberg* and by Bowditch,t N. Baxtt in 1875 carried out in that 
laboratory a prolonged enquiry into the effect produced on the heart’s 
frequence by combined stimulation of the inhibitory (vagus) and accelerator 
(accelerans) nerves going to that organ. His observations were made on 
large dogs; the two nerves were faradised simultaneously. In most of his 
experiments, stimulation of accelerans preceded that of vagus by a few 
seconds, to allow for the well-known longer latency of the former’s reaction ; 
the precurrent stimulation of accelerans alone was immediately followed by 
stimulation of both nerves simultaneously. Baxt found the rate of heart-beat 
under the combined stimulation slowed as though the vagus only and no 
accelerator was in operation ; but, immediately following on cessation of the 
combined stimulation, a full accelerator effect appeared, as though no 
stimulation of the vagus had taken place. Baxt employed usually minimal 
stimulation of vagus and maximal of accelerans, for he found minimal excitation 
of vagus suffice to set aside completely, for the time being, maximal excitation 
of accelerans. In his hands, the result of the combined stimulation was 
vagus action, even when weakest, completely obscuring accelerans action even 
at strongest; but although the accelerans action showed no trace of its 
existence during the vagus stimulation, it appeared in full force after the 
vagus action had passed off. The vagus action, therefore, did not destroy it, 
but merely postponed its appearing. Baxt drew the conclusion that the 
inhibitory nerve and the excitatory nerve must act on separate points in the 
heart’s mechanism and are not true antagonists. This view has since been 
endorsed by many,§ but is not that of v. Cyon, the discoverer of the 
accelerator. 
Another field for examination of the same problem was chosen by 
* ‘ Arbeiten a. d. physiol. Anstalt z. Leipzig,’ 1871. 
+ Ibid., 1873. 
t. Ibéd., 1875. 
§ £.g., Tigerstedt, ‘ Physiologie d. Kreislaufs,’ Leipzig, 1894; for a contrary view see 
S. J. Meltzer, ‘Archiv. f. Physiologie, Leipzig, 1892, p. 376, and v. Cyon, ‘Nerven d. 
Herzen,’ Berlin, 1907. 
