CHAPTER VII. 



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PROPERTIES OF ANIMAL BODIES. 



1. There are various properties which distinguish living 

 from dead animal matter. jBoth, in common, possess certain 

 'physical properties, such as weight, extensibility, flexibility, 

 &c. ; but" Jiving matter has certain physiological or vital 

 properties peculiar to it.| It is these which bring it under 

 the influence of external agents. 



2. ^A.11 the phenomena of life are the effect of impressions 

 made upon the various organs of the body, by external or 

 internal agents^ and each organ has its own proper sti- 

 mulus. Thus the eye is stimulated by light ; the ear by 

 sound, the nose by odours, the organs of taste by condi- 

 ments, &c. 



3. (The chick in its shell is developed by the influence of 

 heat J the seed germinates under the combined effect of 

 warmth and moisture ; and so the growth of the human 

 body requires the application of the appropriate stimulants, 

 such as food, drink, air, exercise, &c. 



4. Every tissue and organ has its own mode of activity. 

 For example, the lungs react under the influence of the air ; 

 the heart under that of the blood ; the muscles under that of 

 the will ; the stomach under that of food, &c. Every gland, 

 though supplied by the same blood, is excited to secrete or 

 form that particular fluid for which it was so designed ; and 

 why the liver does not secrete urine and the kidneys bile, it 

 were useless to inquire. 



5. This property of living matter has three principal 

 modifications in the solids and fluids, which have been called 



{sensitive, motive, and alterative.] fey the sensitive powers, are 

 meant sensibility and its modifications^ (he motive are con- 

 tractility and expansibility '$ jthe alterative are those which 



