TEXT-BOOK OF PHYSIOLOGY. 



THE CHEMICAL CONSTITUENTS OF THE BODY 



AND FOOD. 



By W. D. HALLIBURTON. 



CONTENTS : The Carbohydrates, p. 2 The Fats, p. 17 Lecithin, p. 21 Choles- 

 terin, 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 . J Albuminoids, e.g. gelatin, keratin. 



[Simpler nitrogenous substances, e.g. lecithin, creatine. 



[Fats. 

 NON-NITROGENOUS ^ Carbohydrates, e.g. sugar, starch. 



[Simpler organic substances, e.g. alcohols, lactic acid. 

 VOL. i. i 



