4. 



%jnf* 



CHAPTER II. 



CHEMIC COMPOSITION OF THE HUMAN BODY. 



Since it has been demonstrated that every exhibition of functional 

 activity is associated with changes of structure, it has been apparent 

 that a knowledge of the chemic composition of the body, not only 

 when in a state of rest, but to a far greater degree when in a state 

 of activity, is necessary to a correct understanding of the intimate 

 nature of physiologic processes. Though the analysis of the dead 

 body is comparatively easy, the determination of the successive 

 changes in composition of the living body is attended with many 

 difficulties. The living material, the bioplasm, is not only complex 

 and unstable in composition, but extremely sensitive to all physical 

 and chemic influences. The methods, therefore, which are employed 

 for analysis destroy its composition and vitality, and the products 

 which are obtained are peculiar to dead rather than' to living material. 



Chemic analysis, therefore, may be directed 



1. To the determination of the composition of the dead body. 



2. To the determination of the successive changes in composition 



which the living bioplasm undergoes during functional activity. 



A chemic analysis of the dead body, with a view to disclosing 

 the substances of which it is composed, their properties, their intimate 

 structure, their relationship to one another, constitutes what might 

 be termed chemic anatomy. An investigation of the living ma- 

 terial and of the successive changes it undergoes in the performance 

 of its functions constitutes what has been termed chemic physi- 

 ology or physiologic chemistry. 



By chemic analysis the animal body can be reduced to a number 

 of liquid and solid compounds which belong to both the inorganic 

 and organic worlds. These compounds, resulting from a proximate 

 analysis, have been termed proximate principles. That they may 

 merit this term, however, they must be obtained in the form under 

 which they exist in the living condition. The organic compounds 

 consist of representatives of the r q r b2hyH r atFj fqi-i T; Qrtrl prntpift 

 groups of organic bodies; the inorganic_compounds consist of water, 

 various acids, and inorganic^salts. 



The compounds or proximate principles thus obtained can be 

 further resolved by an ultimate analysis into a small number of 

 chemic elements which are identical with elements found in many 

 other organic as well as inorganic compounds. The different chemic 



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