1908. ] Innervation of Antagonistic Muscles. 567 
discovery that stimulation of the afferent lJaryngeus superior brings the 
diaphragm to rest in the relaxed condition, offered the following explanation 
of this inhibition. The rhythmic action of the respiratory centre results, 
he argued, from the excitation which arises in that centre not having access 
to the motor channels directly, but having to pass a resistance. Through 
this resistance the continuous excitation is transformed into an intermitting 
and rhythmic discharge. This resistance he supposed to be increased by 
stimulation of the superior laryngeal nerve; whence the inhibitory action 
of the nerve. 
It is interesting to find MHeidenhain adopting this explanation, first 
advanced for a central reflex inhibition, as applicable to peripheral inhibitions 
(therefore of his second class), but on the other hand discarding it as little 
applicable to central reflex inhibitions. These latter he considered as for 
the most part belonging to his first class. He gives no specific instance, but 
he is evidently expressing the impression he has derived from his work with 
Bubnoff,* published the previous year, “on excitation and inhibition in 
Motor Cerebral Centres.” In “a great number of the facts known as 
voluntary and reflex inhibition” it is “a matter of the weakening or 
suppression of central excitatory processes by willed or peripheral sensory 
influence.”f And ten years later Meltzer,t from observations “on the 
mutual relation of the nerve-fibres in the vagus which inhibit and 
excite respiration,” distinctly concludes that under maximal stimuli the 
action of one of the opposed nerves regularly hides that of the other (just 
as does the vagus the accelerator’s action and the sympathetic the chorda 
dilating action), but that with submaximal stimuli “giebt es kein 
Ueberwiegen, sondern ein Verschmeltzen zu einer Resultante.”§ 
Reid Hunt|| showed that, as indeed some of Baxt’s own records reveal 
(cf. Meltzer), accelerans stimulation does express itself on beat-rate even 
during vagus excitation. O. Frank{ obtained a similar result; he, however, 
upholds Baxt’s conclusion as legitimate, stressing the fact that while 
accelerans quickens both systole and diastole, vagus slows diastole alone. 
Recently Bessmertny,** from experiments under Asher, also infers that these 
antagonists act at separate places in the cardiac mechanism. Cyon, however, 
* ©Pfliiger’s Archiv,’ vol. 26, p. 137, 1881. 
+ Ibid., vol. 27, p. 283, 1882. 
t ‘Archiv f. Physiologie,’ Leipzig, 1892, p. 341. 
§ Ibid., p. 383. 
|| ‘Amer. Journ. of Physiol.,’ 1894, vol. 2, p. 396. 
“| ‘Sitzungsb. d. Ges. f. Morph. u. Physiol. in Miinchen,’ 1897. 
** ¢ Zeitschr. f. Biol.,’ vol. 47, p. 400, 1905. ' 
