CHEMIC COMPOSITION OF THE HUMAN BODY. 7 



The animal body is therefore not a homogeneous organism, but one 

 composed of a large number of widely dissimilar but related organs. But 

 as all vertebrate animals have the same general plan of organization, there 

 is a marked similarity both in form and structure among corresponding parts 

 of different animals. Hence it is that in the study of human anatomy a 

 knowledge of the form, construction, and arrangement of the organs in 

 different types of animal life is essential to its correct interpretation; also it is 

 that in the investigation and comprehension of the complex problems of 

 human physiology a knowledge of the functions of the organs as they manifest 

 themselves in the different types of animal life is indispensable. As many 

 of the functions of the human body are not only complex, but the organs 

 exhibiting them are practically inaccessible to investigation, we must sup- 

 plement our knowledge and judge of their functions by analogy, by attributing 

 to them, within certain limits, the functions revealed by experimentation 

 upon the corresponding but simpler organs of lower animals. This ex 

 perimental knowledge corrected by a study of the clinical phenomena of 

 disease and the results of post-mortem investigations, forms the basis of 

 modern human physiology. 



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 knowl- 

 edge 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 determina- 

 tion of the successive changes in composition of the living body is attended 

 with many difficulties. The living material, the bioplasm, is not only com- 

 plex 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 



