508 THE SENSORIAL FUNCTIONS. 



as the optic lobes and the medulla oblongata, are 

 those principally concerned in sensation ; and that 

 the cerebellum has considerable influence in regu- 

 lating voluntary motion. 



§ 5. Comparative Physiology of Perception. 



Of the perceptions of the lower animals, and of 

 the laws which they obey, our knowledge must, of 

 necessity, be extremely imperfect, since it must 

 be derived from a comparison with the results of 

 our own sensitive powers, which may differ very 

 essentially from those of the subjects of our obser- 

 vation. The same kind of organ which, in our- 

 selves, conveys certain definite feelings, may, when 

 modified in other animals, be the source of very 

 diflerent kinds of sensations and perceptions, of 

 which our minds have not the power to form any 

 adequate conception. Many of the qualities of 

 surrounding bodies, which escape our more obtuse 

 senses, may be distinctly perceived, in all their 

 gradations, by particular tribes of animals, fur- 

 nished with more delicate organs. Many quadru- 

 peds and birds possess powers of vision incompa- 

 rably more extensive than our own ; in acuteness 

 of hearing, we are excelled by a great number 

 of animals ; and in delicacy of taste and smell, 

 there are few quadrupeds that do not far surpass 

 us. The organ of smell, in particular, is often 

 spread over a vast extent of surface, in a cavity 

 occupying the greatest part of the head ; so that 

 the perceptions of this sense must be infinitely 

 diversified. 



