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to be the case after division of both vagi, implying that those nerves 

 are not the only channels through which this influence is transmitted. 

 A new field of investigation was thus opened. For, supposing the 

 inhibitory agency to be simply the greater action of an ordinary nerve, 

 it would probably not be exercised exclusively by the vagus, but also 

 by the other nerves connecting the cerebro- spinal axis with the car- 

 diac ganglia, viz. the sympathetic branches in the neck ; in which 

 case the action of the heart should be increased or diminished, accord- 

 ing to the strength of the stimulus, 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 per- 

 ceptible to the tip of the tongue were first transmitted. This ex- 

 cessively feeble action of the battery, though apparently not very 

 favourably situated for influencing the cord, produced 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 in- 

 creasing, as before, the rate of the pulsations, diminished it by two 

 in ten seconds on several successive trials. On again half with- 

 drawing 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 cur- 

 rents 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 in- 

 crease 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 car- 

 diac branches arising from the vagi above the parts where they were 

 divided, or even through the trunks of those nerves, which might 



