KEVIEW OF SYSTEM. 



391 



arity of action or sense is governed by aggregations of these, 

 called nerve centers; that, for example, the nerve centers 

 controlling the senses of smelling, tasting, feeling, seeing, 

 balancing, etc., are at the back part or base of the brain ; 

 that the power and activity of these senses are in all cases 

 governed by the strength and activity of such ganglia of 

 nerves. Thus, a hound that follows the scent, or a bird- 

 dog that has the power of smelling game at a distance, has 

 large development of the olfactory nerve ; while the grey- 

 hound, eagle, vulture, etc., that depend upon seeing game 



FIG. 276. Ultimate effects of intemperance. 



at a great distance, have large development of the optic 

 nerve; and others that depend for safety upon hearing, 

 have large development of the auditory nerve. Thus ev- 

 ery peculiarity of animal nature has some special excellence 

 of power, adapted either to aggression or defense. The 

 bee has its sting, the viper its fangs, the bull its horns, and 

 the horse bites, strikes, kicks, etc. 



The front brain, or cerebrum, gives the power of sense, 

 or reason, and animals of but small brain have but very 

 little capacity for being trained or taught, while those hav- 

 ing considerable brain can be easily taught. For example, 

 a fish has very little or no brain, and cannot be taught any- 



