OTHEE SUBSTANCES EMPLOYED. 
501 
that renders the solitary use of a nutritive substance (as 
starch, gum, or sugar) less favourable to assimilation, and 
to the reparation of the losses which the human body under- 
goes. Opium, which is not nutritive, is employed with 
success in Asia, in times of great scarcity; it acts as a 
tonic. But when the matter which fills the stomach can 
be regarded neither as an aliment, that is, as proper to be 
assimilated, nor as a tonic stimulating the nerves, the 
cessation of hunger is probably owing only to the secretion 
of the gastric juice, we here touch upon a problem of 
physiology which has not been sufficiently investigated. 
Hunger is appeased, the painful feeling of inanition ceases, 
when the stomach is filled. It is said that this viscus 
stands in need of ballast; and every language furnishes 
figurative expressions, which convey the idea that a mecha- 
nical distension of the stomach causes an agreeable sen- 
sation. ltecent works of physiology still speak of the 
painful contraction which the stomach experiences during 
hunger, the friction of its sides against one another, and 
the action of the gastric juice on the texture of the diges- 
tive apparatus. The observations of Bichat, and more par- 
ticularly the fine experiments of Majendie, are in contra- 
diction to these superannuated hypotheses. After twenty- 
form, forty-eight, or even sixty hours of abstinence, no 
contraction of the stomach is observed ; it is only on the 
fourth or fifth day that this organ appears to change in a 
small degree its dimensions. The quantity of the gastric 
juice diminishes with the duration of abstinence. It is 
probable that this juice, far from accumulating, is digested 
as an alimentary substance. If a cat or dog be made to 
swallow a substance which is not susceptible of being 
digested, a pebble for instance, a mucous and acid liquid 
is formed abundantly in the cavity of the stomach, some- 
what resembling in its composition the gastric juice of the 
human body. It appears to me very probable, that when 
the want of aliments compels the Ottomacs and the inha- 
bitants of New Caledonia to swallow clay and steatite 
during a part of the year, these earths occasion a powerful 
secretion of the gastric and pancreatic juices in the digestive 
apparatus of these pjople. The observations which I made 
on the banks of the Orinoco, have been recently confirmed 
