EXPERIMENTS ON DIGESTION. 
525 
1. The simple section of the eighth pair of nerves, without ex- 
cision of any part, or change of the direction of the nerve above 
or below the section, will not destroy the digestive power, but only 
retard it. 
2. The section of a nerve, with loss of substance, still more con- 
siderably diminishes the digestive power, but does not quite 
arrest it. 
3. The section or destruction of a portion of the spinal marrow, 
or the excision of a part of the brain, produces the same effect.. 
4. Narcotics given in sufficient quantities to affect the system, 
impair digestion in a proportionate degree. 
5. When digestion is almost entirely suspended after the sec- 
tion or the excision of a part of the pneumo-gastric nerve, it may be 
established by means of electricity or galvanism applied to the 
stomach. The re-establishment of digestion by the aid of the 
electric influence is not confined to the chemical action of the 
stomach on the aliment, but the natural motion of the muscular 
parietes of the stomach is re-established. 
6. The principal office of the par vagum in the function of di- 
gestion consists in exciting the peristaltic motions of the stomach, 
and bringing the gastric juice into more complete contact with the 
aliment. 
7. The suspension of digestion after the section of the pneu- 
mogastric nerves consists in paralysis of the muscular tunic of the 
stomach. 
Although the motion of the stomach appears principally to de- 
pend on the influence of the par vagum, and the irritants, me- 
chanical and chemical, which act upon this nerve determine also 
contraction of the muscular membrane, it nevertheless would seem 
probable that the secretion of the gastric juice, and its acid cha- 
racter, are, at least partly, dependent on the pneumo-gastric nerves, 
and that the impairment of digestion which succeeds to the section 
of these nerves proceeds from the want of the acid gastric juice. 
The opinion that the secretion of the gastric juice is under the 
influence of the nervous system appears to derive some support 
from the phenomena observable in the sheep that died a few hours 
after the removal of the pancreatic juice. Although the animal 
had eaten a considerable quantity of oats before the operation, the 
liquid and the grain which the abomasum contained were not acid 
but alkaline, and strongly effervesced w r ith acids. Here the nerv- 
ous action appeared to have been so enfeebled by the painful 
operation that had been performed, that the secretion of the acid 
gastric juice was no longer effected. 
It is possible that the ramifications of the great sympathetic, 
which penetrate with the arteries into the walls of the stomach, 
VOL. xii. 3 z 
