140 
DR. PHILIP ON DIGESTION. 
animal survives the operation eighteen, twenty, or more hours, undigested food 
alone is found in it. The cause of so long a time being required wholly to 
expel the food, which has undergone any degree of the digestive process, 
appears to be, that as digested food alone excites that action of the stomach 
which propels it into the intestine, and the more perfectly it is digested, it 
excites this action the more readily, the last part of the digested food which 
has but imperfectly undergone the digestive process is expelled very slowly, so 
that it is very long before food wholly undigested alone is left. 
That the longer the animal lives after the excision of part of the eighth pair 
of nerves, the less digested food is left in the stomach, is a fact now admitted 
by all who assisted at the experiments. Among the great number who have 
witnessed and been satisfied with their result, are Sir Humphry Davy", Mr. 
Thomas Andrew Knight, and Mr. Brodie, gentlemen whose experimental 
accuracy, in the opinion of the public, has never been surpassed. 
Of this fact, the gentlemen to whose paper I have referred, are not aware. 
They maintain, indeed, that the only effect on the digestive process produced 
by the excision of part of the eighth pair of nerves, is, that it becomes more 
tedious, being as perfect as when the nerves are entire, if a sufficient length of 
time be afforded. In speaking of the animals in which part of the eighth pair 
of nerves has been cut out, and comparing them with the healthy animal, they 
say : “ Enfin, si on laisse ecouler un espace de temps plus grand encore entre 
l’operation et la mort des animaux, on pourra trouver que la digestion est com- 
pletement aclievee dans fun comine dans l’autre cas.” 
It will easily be perceived to what errors, respecting the effect on digestion, 
of depriving the stomach of the office of the eighth pair of nerves, this miscon- 
ception must lead. Its effect was increased in the experiments referred to, 
by the different animals in each experiment having been confined to the same 
quantity of food. The most hungry would of course digest it fastest and most 
perfectly. To judge fairly of the result of the experiment the different animals 
must he allowed equally to satisfy their appetite, to eat till, from their manner 
of eating, it is found that the appetite has equally abated in all. 
Such are the circumstances which I conceive misled those gentlemen who 
maintain that they can produce a sensible effect on the contents of the stomach 
by any mechanical irritation of its nerves. 
