40 TEXT-BOOK OF PHYSIOLOGY. 



chemic inertia. C possesses the great atomic cohesion. O is noted 

 for the number and intensity of its combinations. 



As the properties of the compounds formed by the union of 

 elements must be the resultants of the properties of the elements 

 themselves, it follows that the ternary compounds, starches, sugars, 

 and fats must possess more or less inertia, and at the same time 

 instability; while in the more complex proteids, in which sulphur 

 and phosphorus are frequently combined with the four principal 

 elements, molecular instability attains its maximum. As all the 

 foregoing compounds possess in varying degrees the properties of 

 inertia and instability, it follows that living matter must possess 

 corresponding properties, and the capability of undergoing unceas- 

 ingly a series of chemic changes, both of composition and decom- 

 position, in response to the chemic and physical influences by which 

 it is surrounded, and which underlie all the phenomena of life. 



PRINCIPLES OF DISSIMILATION. 



In addition to the previously mentioned compounds, viz., 

 carbohydrates, fats, proteids, and inorganic salts, there is obtained 

 by chemic analysis from the tissues and fluids of the body: 



1. A number of organic acids, such as acetic, lactic, oxalic, butyric, 



propionic, etc., in combination with alkaline and earthy bases. 



2. Organic compounds, such as alcohol, glycerin, cholesterin. 



3. Pigments, such as those found in bile and urine. 



4. Crystallizable nitrogenized bodies, such as urea, uric acid, xanthin, 



hippuric acid, creatin, creatinin, etc. 



While some few of these compounds may possibly be regarded as 

 necessary to the physiologic integrity of the tissues and fluids, the 

 majority of them are to be regarded as products of dissimilation of 

 the tissues and foods in consequence of functional activity, and 

 represent stages in their reduction to simpler forms previous to being 

 eliminated from the body. 



