88 PRELIMINARY ACCOUNT OF AN INQUIRY INTO 
quiescence of the heart or intestines on irritation of the vagus or splanchnic nerves 
was analogous to that of arterial dilatation in the web, and that, provided a suf- 
ficiently mild stimulus were applied to the so-called ‘inhibitory nerves’, increased 
action of the viscera would occur, corresponding to the vascular constriction. 
To test the truth of this hypothesis, I made several experiments between 
the 17th of June and the 14th of July of this year, with regard to the movements 
of the heart and intestines. The means used for stimulating the nerves and 
spinal cord were sometimes mechanical irritation, but more commonly galvanism, 
applied with a magnetic coil battery of a single pair of plates, the strength of 
which could be regulated in a rough way, with great facility, by the height 
at which the acid solution stood in the jar and the extent to which the rods 
of soft iron were inserted in the helix. The mildest action employed was such 
as was but just perceptible to the tip of the tongue, placed between the fine 
silver-wire extremities of the poles, when the rods were fully in the helix, but 
inappreciable after their complete withdrawal; the spring carrying the 
magnetic bar being made to vibrate by a touch with the finger: the greatest 
action of the battery, on the other hand, was so powerful as to elicit sparks 
when the poles were applied to the tissues. 
My attention was first directed to the intestines, and it may be well to 
mention first all the results obtained with reference to them. The animals 
operated on were generally rabbits, they being very easily managed, and also 
favourable for the purpose on account of the large amount of movement which 
occurs in their intestines. Chloroform was generally not administered, on 
account of its depressing effect upon the action of the nervous centres. 
In the first experiment, the ends of the poles having been fixed to the 
spinous processes of the ninth and twelfth dorsal vertebrae, according to Pfliiger’s 
original method, and the intestines allowed to protrude through a wound in 
the abdominal parietes, a series of interrupted currents were transmitted, a very 
small amount of acid being in the jar, and the rods fully in the helix. The 
effect was complete relaxation and quiescence of the small intestines, which 
had been previously in considerable movement, while the muscles of the limbs 
were thrown into spasmodic action ; but on the discontinuance of the galvanism 
the previous intestinal motion returned. The rods were then removed from the 
helix, and the battery, thus diminished, was applied on several occasions, with 
markedly increased action of the intestines in every instance during the first 
twenty-five minutes. In the next half-hour the increase of action from the 
galvanism, though still distinct, was less strongly marked; and at the end 
of that period, the rods having been reintroduced, the inhibiting influence 
was also found to be much less complete than before, indicating that the parts 
