80 CHEMICAL COMPOSITION OF THE BODY. 



CHAPTER IV. 



CHEMICAL COMPOSITION OF THE BODY. 



52. THE elements which enter into the composition of the various fluids 

 and solids of the body are Oxygen, Hydrogen, Nitrogen, Carbon, Sulphur, 

 Phosphorus, Chlorine, Fluorine, Potassium, Sodium, Lithium, Calcium, 

 Silicum, Magnesium, and Iron. Lead and copper are occasionally, but per- 

 haps only accidentally, present. 1 The combinations of these elementary 

 bodies are divisible into two great groups: the Inorganic, represented by the 

 saline constituents, in which they are united for the most part in a binary 

 manner, and the Organic, in which the chemical constitution is much more 

 complicated, but which are again easily subdivisible into the azotized com- 

 pounds represented by the albuminous substances and their derivatives, and 

 the nonazotized compounds, which include the oleaginous and the saccharine 

 substances. The inorganic compounds are commonly associated with the 

 organic in sufficient quantities to maintain the body in health, if the food be 

 sufficiently varied, though in one or two instances as in those of the use of 

 water and of common salt an additional supply is taken in the pure state. 

 The organic group is primarily and entirely derived from the Vegetable 

 Kingdom, the office of which is to produce, from the surrounding air, water, 

 and soil, the complex materials of which the bodies of animals are con- 

 structed. The inorganic compounds undergo comparatively little change in 

 passing through the body, but the organic and especially those belonging 

 to the azotized or albuminous type, which have a complicated constitution, 

 their molecules being larger, and containing many atoms held together by 

 comparatively feeble affinity are correspondingly liable to break down 

 under the influence of disintegrating causes, and by their oxidation to yield 

 the various forms of force which the animal body exhibits. If, for instance, 

 we follow the changes undergone by the albuminous group we shall find that 

 they no sooner enter the stomach than they are placed under conditions, 

 namely, warmth and moisture, that are particularly favorable to decomposi- 

 tion. The peculiar properties of the gastric juice, however, retard and, at 

 the same time, modify the changes they would otherwise undergo. By ren- 

 dering them soluble it enables them to be absorbed into the blood, where 

 they are exposed to the action of oxygen, in a very active state, dissolved in 

 an alkaline fluid. A portion is probably immediately applied to the main- 

 tenance and reconstruction of the tissues, and to the formation of the albumi- 

 noid constituents of the various secretions, which, in the form of Mucin, 

 Collagen, Spermatin, etc., may be regarded as the immediate derivatives of 

 albumen, whilst a part remains in solution in the blood. Both portions alike 

 that which forms part of the tissues, and that which forms part of the 

 blood sooner or later unite with oxygen, and appear to break up into two 

 groups of compounds, the azotized and the nonazotized. The former include 



1 See Blamis, Zeits. f. Rut. Mod., IJ. xxvi, p. 'Jf>0; and Lessen, Journal f. Chemie, 

 18GG, p. 4GO. 



