58 INTRODUCTION, 



We can form no clear notion of the immediate 

 cause of instinct, other than by admitting that 

 animals subject to it have in their sensorium images 

 or sensations, which are innate and perpetual. By 

 these, those particular modes of action must be de- 

 termined, in the manner the common modes are by 

 ordinary and accidental sensation. The individuals 

 are haunted, as it were, by a perpetual dream or 

 vision, and in every thing that has reference to their 

 instinctive peculiarities they may be considered as 

 a kind of somnambulists. Instinct has been granted 

 to animals to supply the deficiencies of intelligence, 

 and to unite with it and with physical strength and 

 fecundity in the preservation of all the species, to 

 the extent prescribed by the fiat of the Creator. 



Instinct is not ascertained to be characterized by 

 any visible mark in the conformation of the animal ; 

 but intellect, as far at least as we can observe, bears 

 a constant proportion to the relative magnitude of 

 the brain, and particularly of its two hemispheres. 



Of method, or system, i?i its application to the Animal 

 Kingdom. 



After what has been said concerning systems in 

 general, it remains now to examine what are the 

 most influential characters in the animal creation, 

 which may be selected as proper foundations where- 

 on to rest the primary divisions of this portion of 

 natural history. 



