CRITICAL NOTICES OF NEW PUBLICATIONS. 511 
theories have been given to account for the phenomenon. The 
proximate cause of hunger has by some been conceived to depend on 
the friction of the nervous papilla of the empty stomach on each 
other ; by others it has been imputed to the irritation produced on 
its parieties by the accumulation of the gastric juice ; it has been 
thought to depend on the dropping down of the liver and spleen, 
when the stomach and intestines; being empty, cease to support those 
viscera. Magendie, convinced that all the theories on this subject 
were unsatisfactory, comes to this conclusion, that “ hunger is pro- 
duced, like all other internal sensations, by the action of the nervous 
system; and it has no other seat than in this system itself, and no 
other cause than the general laws of organization.” This subject 
is unquestionably involved in considerable doubt and obscurity, but, 
although confessedly obscure, we are not denied the privilege of 
patient investigation, and persevering search after truth. Anxious 
mainly to elicit investigation on the subject, Dr. Beaumont submits 
the following theory of hunger, believing it to be as reasonable, to 
say the least, as any that has been propagated. Dr. B’s impression 
is, that the sensation of hunger is produced by the distension of the 
gastric vessels, or that apparatus, whether vascular or glandular, 
which secretes the gastric juice, and is believed to be the effect of 
repletion by this fluid. On applying aliment to the internal coat 
of the stomach, which in health is merely lubricated with mucus, 
innumerable minute papille, the orifices undoubtedly of the gastric 
vessels, immediately throw out a quantity of the fluid, which mixes 
with the food. This effect, Dr. B. adds, is too sudden, and the 
secretion too copious, to be accounted for on the ordinary principles 
and laws of secreting mucous surfaces. And it is more than proba- 
ble, he observes, in fact, it almost amounts to demonstration, that a 
large quantity of this fluid must be contained in appropriate vessels, 
during a fast, ready to obey the call of aliment. Not that our au- 
thor would be understood to say that the whole quantity necessary 
for an ordinary meal is eliminated previous to the commencement of 
alimentation ; but that enough is contained in the gastric vessels to 
produce the sensation of hunger. 
Thirst, like hunger, is a wise provision of nature, designed, not to 
replenish the watery solids of the system, but to dilute the fluids 
that are carrying on these processes. The calls of thirst are still 
more absolute than those of hunger, and it is much less patiently 
endured. Dr. B. apprehends a remote cause of this sensation may 
be found in the viscidity of the blood, which requires a liquid to ren- 
der it more fluid, and more susceptible of introduction into the ca- 
pillaries and secreting surfaces. Dr. Beaumont candidly offers 
these theories for consideration, persuaded that they will be allowed 
such weight as they may have a right to claim ; more than this he 
has no wish to ask. 
The preliminary steps in the process of digestion are mastication, 
insalivation, and deglutition. If the materia alimentaria could be 
introduced into the stomach in a finely divided state, these operations 
