174 
EXPERIMENTS ON DIGESTION. 
He had previously, in conjunction with Professor Gmelin, pub- 
lished a work on Digestion, which has not been translated into our 
language. The w r ork was, probably, deemed too profound even for 
the common medical reader. It includes the four classes of ver- 
tebrated animals, the mammalia, birds, reptiles, and fishes. It 
commences with the consideration of the properties and chemical 
composition of the various glandular secretions which are con- 
cerned in digestion — -the saliva, pancreatic juice, bile, gastric juice, 
&c., and inquires into the alimentary substances, whether animal 
or vegetable, which are received into the alimentary canal, and 
the changes which they undergo in the several divisions or com- 
partments of that canal. These are most interesting inquiries, and 
the result of each is verified by the most ingenious and careful 
experiments. 
In many a future number it is our intention to translate these 
results as it regards our patients. They will afford us pretty nearly 
all that we can w r ant. 
The Saliva. 
In all animals, with the exception, perhaps, of the cetacea, there 
are found around the cavity of the mouth many conglomerated 
glands, of different forms and magnitude, which secrete from the 
blood a peculiar fluid called the saliva, and which is furnished by 
certain excretory canals. The size of the different glands, and the 
situation of the orifices of their excretxny canals, have, to a certain 
point, in the mammalia, a relation to the situation of the teeth, and 
to the part of the mouth in w hich the aliment is chiefly submitted 
to the action of the teeth. The secretion of the saliva in a small 
quantity is continually going forw'ard ; but it is most abundant when 
food has been introduced into the buccal cavity, and begins to 
exercise its influence on the nerves of the tongue and the mucous 
membrane of the mouth. This influence is propagated to the sali- 
vary glands by means of the second and third branches of the fifth 
pair of nerves, and it disposes these organs to furnish a copious 
secretion of the salivary fluid. The salivary secretion is equally 
great, w r hen effluvia from the food are brought in contact wdth 
the membrane of the nose ; and in this case the exciting influence 
appears to be transmitted to the nerves of the salivary glands by 
the posterior nasal nerve which emanates from the spheno-palatine 
ganglion. 
The Professor submits the salivary fluid of the human being, 
the dog, and the sheep to various chemical analyses, from which 
the following are the results. 
1. The saliva does not contain more than from 1*0 to 2*5 per 
