HUMAN PHYSIOLOGY. 



CHAPTER I. 



DEFINITION ; ORGANIC AND INORGANIC BODIES. 



1. PHYSIOLOGY is " the science of life," or that branch 

 of knowledge which explains the uses of the various. organs 

 of living beings. Vegetable physiology treats of the func- 

 tions of plants ; and Comparative physiology, of those of the 

 inferior orders of animals ; while Human physiology treats 

 exclusively of man. 



2. The kingdom of nature embraces three great classes, 

 ANIMALS, VEGETABLES, and MINERALS. According to a more 

 scientific arrangement, it is composed of organic and inor- 

 ganic bodies. By' organic bodies, we mean those which 

 possess organs or instruments for the performance of certain 

 functions ; and by inorganic, those which do not. It is by 

 a knowledge of these works of God, that we derive our ideas 

 of his power, wisdom, and goodness. 



3. Organized bodies are divided into two great classes, 

 animals and vegetables ; which differ from inorganic matter 

 in several respects, the most important of which are the 

 following : 



4. Organized bodies have a certain determinate form, 

 peculiar to the species to which they belong. Every species 

 of plant or animal may be known by its external shape ; as 



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