94 PRELIMINARY ACCOUNT OF AN INQUIRY INTO 
by the application of galvanism to the cervical region of the spine after the 
pneumogastric nerves had been cut. 
In an experiment performed with this view, the poles having been fixed 
to about the fourth cervical and fifth dorsal spinous processes, and both vagi 
divided in the neck, galvanic currents only just perceptible to the tip of the 
tongue were first transmitted. This excessively feeble action of the battery, 
though apparently not very favourably situated for influencing the cord, pro- 
duced marked effects upon the heart’s action, increasing the number of beats, 
which were about forty in ten seconds, by from three to ten in that period. 
This effect having been observed for a considerable time, the rods of soft iron, 
which had been till then only inserted half-way in the helix, were pushed fully 
in. The battery, thus strengthened, instead of increasing, as before, the rate 
of the pulsations, diminished it by two in ten seconds on several successive 
trials. On again half withdrawing the rods, the galvanism, when applied, again 
increased the number of beats. A little more of the acid solution was after- 
wards poured into the jar of the battery, when the stronger currents which it 
produced reduced the number by about five in ten seconds. 
Yet distinct as was this inhibiting influence, the shocks were still quite 
tolerable to the tongue even when the rods were fully in the helix. 
These results were of great interest, as proving how slight an increase 
of the feeble stimulus which promoted the action of the heart sufficed to produce 
the opposite (inhibiting) effect. But it was by no means clear that the influence 
had not been exerted through cardiac branches arising from the vagi above 
the parts where they were divided, or even through the trunks of those nerves, 
which might possibly have been affected by the galvanism acting through the 
superjacent spinal column. In order to eliminate the vagi completely, I divided 
in another rabbit all the soft parts in front of the spine, except the trachea 
and oesophagus, at the level of the cricoid cartilage, having previously cut each 
carotid artery between two ligatures. The incisions were carried fairly down 
to the bodies of the vertebrae, and outwards beyond the tips of the transverse 
processes, so as to ensure the section not only of the vagi and their branches, 
but also of the sympathetic cords, with any filaments of those nerves which 
they might contain. Also the poles of the battery were fixed to the spinous 
processes of the seventh dorsal and first lumbar vertebrae, so as to avoid all 
possibility of direct action of the galvanism upon either the vagi or other cardiac 
nerves. Feeble currents being then transmitted, diminution of the number 
of beats to the extent of two to four in ten seconds occurred in several successive 
trials, the results being so constant as to leave no doubt that they were produced 
by the galvanism. 
