TEXT-BOOK OF PHYSIOLOGY. 
THE CHEMICAL CONSTITUENTS OF THE BODY 
AND FOOD. 
By W. D. Halliburton. 
Contexts : — The Carbohydrates, p. 2 — The Fats, p. 17 — Lecithin, p. 21— Choles- 
teriii, p. 22 — The Proteids, p. 24 — Decomposition Products of Proteids, p. 28 — 
Synthesis of Proteids, p. 35 — Theories of Proteid Constitution, p. 38 — General 
Properties and Reactions of Proteids, p. 39 — Classification of Proteids, p. 49 — 
Vegetable Proteids, p. 51 — Poisonous Proteids, p. 55 — Compound Proteids, p. 61 
■ — The Albuminoids, p. 69 — Inorganic Compounds, p. 76. 
The chemical constituents of the body are very numerous, and the 
majority of them are compounds of complicated structure. In the 
following article I propose to treat of these compounds, first in classes, 
and then individually, and in a subsequent chapter to discuss the various 
tissues and organs in their chemico-physiological aspects. 
In order to classify the chemical constituents of the body, one might 
proceed upon a purely chemical basis, beginning with the simplest and ending 
with the most complex compounds; or a purely physiological basis might be 
adopted, in which the compounds would be described in the order of their im- 
portance in the vital processes of the organism. But a compromise between these 
two exclusive methods is found to be that which is of most practical usefulness. 
"We may, in the first place, divide the compounds found in the body 
into those of inorganic, or mineral nature ; and those which are termed 
organic, or carbon compounds. 
The inorganic compounds present are water ; various acids, such as 
the hydrochloric acid of the gastric juice ; and numerous salts, such as 
calcium phosphate in bone, and sodium chloride in blood, urine, etc. 
The organic compounds are more numerous, and these we may 
conveniently group as follows : — 
(Proteids, e.g. albumin, myosin. 
Nitrogenous . - Albuminoids, e.g. gelatin, keratin. 
[Simpler nitrogenous substances, e.q. lecithin, creatine. 
(Fats. 
Non-nitrogenous J Carbohydrates, e.g. sugar, starch. 
[Simpler organic substances, e.g. alcohols, lactic acid. 
VOL. I.— I 
