PROXIMATE CONSTITUENTS OF THE BODY. 71 



even after death, by the hence so-called yellow elastic tissue, is a 

 purely physical property, which is manifested only so long as the 

 tissue itself retains a sufficiency of its combined water. 



The remarkable permeability of the animal tissues, and we may add, 

 of vegetable tissues also, to water and watery solutions, is a character 

 which, physically considered, is, to a certain extent, dependent on the 

 previous natural existence of water in them ; for had they been satu- 

 rated with some other fluid, as oil, for example, they would have re- 

 sisted the percolation of water and watery solutions. The phenomena 

 attending the passage, in opposite directions, of water, and of various 

 substances dissolved in that fluid, through dead organic membranes, 

 described by Dutrochet under the designations of Endosmosis and Ex- 

 osmosis, and more recently by Graham, under the terms Osmosis and 

 Dialysis, will be considered in the chapter on Absorption. 



THE CHEMICAL COMPOSITION OF THE BODY. 



If the tissues and organs of the body are subjected to various pro- 

 cesses of chemical analysis, either by being allowed to coagulate, or 

 by being coagulated by means of heat ; by being washed or boiled in 

 water for a long time, or by being dried and treated with alcohol and 

 ether, certain products being then obtained by filtration and evapora- 

 tion ; or lastly, by being burnt to ashes, it is found that they yield 

 a number of substances which are called the proximate constituents of 

 the body, because they are the first chemical compounds into which 

 the several tissues may be made to resolve themselves. Some of these 

 being peculiar to organized bodies are named accordingly, the organic 

 proximate constituents ; whilst others, found in the mineral kingdom 

 also, are called the inorganic proximate constituents. The former, 

 however, are by putrefaction or destructive heat, still further decom- 

 posed into ultimate chemical elements, which themselves belong to the 

 mineral kingdom. 



The Proximate Chemical Constituents of the Body. 



The chief inorganic proximate constituent of the body is water. 

 Next to this in quantity is phosphate of lime. Then the carbonate of 

 lime, chloride of sodium (common salt), chloride of potassium, phos- 

 phates, sulphates, and carbonates of soda and potash, phosphates and 

 carbonates of magnesia, fluoride of calcium, and certain compounds 

 containing iron, silica, and manganese, besides traces of probably acci- 

 dental substances, such as copper, lead, and aluminium. To these we 

 must also add ammonia, which exists in combination with the urine, 

 and likewise the gases named carbonic acid, oxygen, and nitrogen. 



The organic proximate constituents are of two kinds. One kind 

 contains the chemical element azote or nitrogen, and is hence called 

 azotized or nitrogenized. These readily decompose and yield ammonia 

 when they are burnt or putrefied. They are albumen and its allied 

 substances, vitellin, globulin, and fibrin, gelatin, chondrin, and 

 elastin mucus and horny matter,- extractive matters, crystallizable 

 and non-crystallizable, coloring matters, red and black, a peculiar 



