96 PRELIMINARY ACCOUNT OF AN INQUIRY INTO 
the agency in them of either the vagi or the part of the brain from which the 
vagi spring, having been performed upon decapitated rabbits. In one of these 
cases, the carotids having been tied near the head, the neck was completely 
severed behind the first vertebra, care being taken to avoid haemorrhage from 
the vertebral arteries, and artificial respiration, for which provision had been 
made, was carried on for an hour and a half after decapitation. The results 
of moderate galvanism, applied to the posterior dorsal region of the spine, to 
which the poles had previously been attached, were at first not distinct, but 
afterwards decided increase of action was produced by it when applied at inter- 
vals during half an hour, the effect being perfectly apparent in the heart which 
lay exposed before me. Exhaustion of the nerves concerned having then taken 
place, the most powerful action of the battery failed to influence the character 
of the contractions. 
In the other case, the poles having been fixed as before, and the head simi- 
larly removed, powerful galvanic currents were immediately transmitted. The 
pulsations of the heart in the opened chest at once fell from thirty-five to sixteen 
in ten seconds, but rose again to twenty on the removal of the stimulus. 
Hence it is clear that the sympathetic branches connecting the cord with 
the cardiac ganglia have equal claims with the vagi to be called ‘ inhibitory 
nerves’. In fact this expression seems to me altogether objectionable, since 
there is good reason to think that the same fibres which check the movements 
much more commonly enhance them. The only evidence afforded by my 
experiments that the inhibiting influence is ever exerted in the natural actions 
of the animal consisted in the quiescence of the intestines sometimes seen after 
a struggle, and two doubtful observations of retardation of the heart’s beats 
from the same cause. Indeed it appears very questionable whether the motions 
of either of these viscera are, under ordinary circumstances, ever checked by 
the spinal system, except for very brief periods ; whereas the increased action 
of both heart and intestines, familiarly known to result from mental emotion, 
may last for a very considerable time. The fact that the nerves of these organs 
are capable of setting them at rest under conditions of extraordinary irritation 
is nevertheless a matter of great importance, especially in a pathological point 
of view, and appears to afford an explanation of facts in medicine hitherto little 
understood—such as failure of the heart’s action from violent emotion or pain, 
and the constipation which attends strangulated omental hernia. 
From the observations of Spiegelberg,’ it would appear that the uterine 
contractions are promoted by mechanical irritation of the cord, and arrested by 
transmitting a powerful stream of galvanism through the spine. Also the forcible 
* Henle and Pfeufer’s Zeitschrift, 3rd series, vol. li, part I. 
