ON DIETETICS. 
435 
the actions induced by various articles of food are admitted 
to be non-medicinal. In our ordinary systems of feeding, 
a single object is usually sought, viz., that of preserving the 
bulk of the body, or even of adding to it; we recognise 
from habit the fact that aliment is capable of doing so much 
under ordinary circumstances. 
During the general disturbance occasioned by disease, the 
digestive functions are impaired, and, under such circum¬ 
stances, refuse to appropriate food which, up to this, has 
sufficed for the support of the system ; the question now 
arises as to what kind of aliment is adapted to the altered 
condition of the organism. In pursuing this inquiry, it is 
necessary to ascertain something of the effects of various 
articles of food upon the animal in health and disease. 
Physiological Action of Pood . 
Without entering into a minute consideration of the 
digestive process, it will suffice for our purpose to trace the 
food through its various changes in the course of its conver¬ 
sion into the components of the animal organism. 
In the mouth the aliment is commixed with saliva, in the 
stomach it meets the gastric juice, in the duodenum the 
biliary and pancreatic secretions, in the intestinal tube 
throughout with various amounts of mucous secretion; by 
the agency of the lacteals its nutritious portions are conveyed 
into the venous circulation, and, finally, in the lungs it un¬ 
dergoes its last stage of elaboration, and adds to the supply 
of arterial blood. 
Throughout this process food acts as a stimulant to the 
glands and membranes connected with the digestive system; 
its ultimate destination is the circulatory system, whose losses 
it is required to supply. Physiologically, therefore, food ex¬ 
cites secretion; improves the quality, and quantity, of the 
blood; and furnishes material for the support, reparation, 
and growth, of the tissues. Within certain limits these 
offices are performed with an energy directly proportioned 
to the amount of food supplied ; thus a liberal diet is followed 
by activity of the nutritive functions, and excessive develop¬ 
ment of the structures ; on the other hand, a meagre allowance 
necessitates defective deposits and emaciation. 
By a selection of certain kinds of food, rich in a particular 
class of constituents, either the fatty or the azotized 
structure may alternately be made to preponderate, always 
in subservience to the peculiar aptitude in the system to 
develope fat or flesh out of the proximate principles supplied. 
