522 
EXPERIMENTS ON DIGESTION. 
which any particular agent lends to the accomplishment of this ob- 
ject. The most distinguished chemists have frankly avowed their 
ignorance on this point. 
The gastric juice of dogs, and cats, and horses, and the fluid in 
the abomasum of ruminants, is of an acid character. That acidity 
is the same whether the mucous membrane of the stomach is sti- 
mulated by mechanical or chemical agents, or by the accumulation 
and impression of food. The acids which are found in the gastric 
juice are the acetic and hydrochloric, to which, in horses and cattle, 
may be added the butyric. It is a question, even at the present 
day, to what the gastric juice owes the solvent property which it 
exercises on the food, and whether it is indebted to the acids which it 
contains for its power of dissolving the principal simple nutritives. 
The water which the gastric juice contains effects the dissolu- 
tion of many simple aliments which are soluble in that fluid; such 
are uncoagulated albumen, gelatine, osmazome, sugar, gum, and 
starch. The solution of these substances is accelerated by the 
heat of the stomach, and it should be rapidly accomplished at a 
temperature of 96 Fah. 
The acetic and hydrochloric acids which enter into the com- 
position of the gastric juice dissolve many simple aliments, which 
are not soluble in water, as concrete albumen, fibrine, coagulated case- 
ous matter, gluten and gliadine — a substance analogous to gluten, 
and which is found in many of the legumina and cerealia. They 
also effect the dissolution of the cellular textures, membranes, 
tendons, cartilages, and bones. As the dissolving of these sub- 
stances, out of the body, is accelerated by heat, it has the same 
effect within the stomach, where they are continually exposed to 
a high temperature. 
During their solution, many of the alimentary substances un- 
dergo a species of decomposition. Starch in the act of dissolving 
loses its property of colouring iodine blue, and is converted into 
sugar and gum. Something analogous to this takes place with 
regard to many other substances. Perhaps these modifications do 
not entirely depend on the free acids which the gastric juice con- 
tains, but on matters analogous to saliva and ozmazome, which that 
fluid possesses, for gluten exercises an analogous action on starch. 
Chemists have not come to any satisfactory conclusion on the 
solvent action of the but} r ric acid on simple aliments; but as it is 
found in the gastric juice of the horse, and in the fluid of the abo- 
masum, it is fair to presume that in both it possesses the property 
of dissolving the alimentary substances. 
If the gastric juice, which the living stomach secretes from the 
blood, in consequence of a stimulus exercised on its parietes, owes 
to the water, and the acetic and hydrochloric acid, and the different 
