CHEMICAL COMPOSITION OF THE HUMAN BODY. 15 



when subjected to desiccation, becoming solid; but upon exposure to 

 moisture they again absorb water, regaining their original condition they 

 are hygroscopic. Another property is that of coagulation, which takes 

 place under certain conditions : e.g., the presence of mineral acids, heat, 

 alcohol, etc. 



After death the nitrogenized compounds undergo putrefactive changes, 

 give rise to carburetted and sulphuretted hydrogen and other gases. In 

 order that these changes may take place it is essential that certain condi- 

 tions be present: viz., atmospheric air or some fluid containing oxygen, 

 moisture, and a temperature varying between 60 and 90 F. The cause 

 of the putrefactive change is the presence of a minute unicellular organ- 

 ism, the bacterium termo. 



The nitrogenized bodies found in the organism are quite numerous, and 

 although they resemble each other in many particulars, there are yet 

 important differences, and can be arranged into the following groups : 



1. NATIVE ALBUMINS. Proteid bodies soluble in water, many acids, and 

 usually in alkalies; coagulable at a temperature of from 140 to 163 F. 



a. Serum Albumin, the principal form of albumin found in the animal 

 fluids and solids. 



b. Egg albumin, not found in ordinary tissues, but present in white 

 of egg. 



2. GLOBULINS. Proteid bodies insoluble in water, but soluble in solutions 

 of sodium chloride. 



a. Globulin, found in many tissues, but largely present in crystalline 

 lens. 



b. Myosin, found in the muscles in life in a fluid condition; after 

 death it undergoes coagulation, giving rise to the rigidity of the 

 muscles. 



c. Paraglobulin, present in blood and obtained from it by passing a 

 stream of carbon dioxide through it; it is also precipitated by 

 adding sodium chloride. 



d. Fibrinogen, present in serous fluid and blood, and can be precipi- 

 tated by the prolonged use of carbon dioxide ; it is also precipitated 

 by the addition of 12 to 1 6 per cent, of sodium chloride. 



3. DERIVED ALBUMINS. Proteid bodies which are not coagulable by heat; 

 insoluble in pure water and in salt solutions ; soluble in both acid and 

 alkaline solutions. 



a. Acid Albumin, found principally in the stomach during first stage 

 of digestion, the result of the action of the hydrochloric acid upon 

 the albumin of the food. 



