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Chapter XIV. 



NERVOUS POWER. 



The organs which are appropriated to the per- 

 formance of the various functions conducive to 

 nutrition, are generally designated the vital 

 organs, in order to distinguish them from those 

 which are subservient to sensation, volun- 

 tary motion, and the other functions of animal 

 life. The slightest reflection on the variety and 

 complication of actions comprised under the 

 former class of functions in the higher animals, 

 will convince us that they must be the result 

 of the combined operation of several different 

 agents ; but the principal source of mechanical 

 force required by the vital organs, is still, as in 

 all other cases, the muscular power. The coats 

 of the stomach and of the intestinal tube contain 

 a large proportion of muscular fibres, the con- 

 tractions of which effect the intermixture and 

 propulsion of the contents of these cavities, in 

 the manner best calculated to favour the che- 

 mical operations to which they are to be sub- 

 jected, and to extract from them all the nourish- 

 ment they may contain. In like manner, all 



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