PART III. 



THE SENSORIAL FUNCTIONS. 



Chapter I. 



SENSATION. 



The system of mechanical and chemical func- 

 tions which we have been occupied in reviewing, 

 has been established only as a foundation for 

 the endowment of those higher faculties which 

 constitute the great objects of animal existence. 

 It is in the study of these final purposes that 

 the scheme of nature, in the formation of the 

 animal world, opens and displays itself in all its 

 grandeur. The whole of the phenomena we 

 have hitherto considered concur in one essential 

 object, the maintenance of a simply vital exist- 

 ence. Endowed with these properties alone, the 

 organized system would possess all that is abso- 

 lutely necessary for the continuance and support 

 of mere vegetative life. The machinery pro- 

 vided for this purpose is perfect and complete in 

 all its parts. To raise it to this perfection, not 



