470 TNSTINfrT OF INSECTS. 



the infant seeks for its mother's breast, is the effect of 

 reason. 



Instinct, then, is not the result of a plastic nature ; 

 of a system of machinery ; of diseased bodily action ; 

 of models impressed on the brain ; nor of organic 

 shootings-out '.■ — it is not the effect of the habitual de- 

 termination for ages of the nervous fluid to certain or- 

 gans; nor is it either the impulse of the Deity, or 

 reason. Without pretending to give a logical defini- 

 tion of it, which while we are ignorant of the essence 

 of reason is impossible, we may call the instincts of 

 animals those unknown faculties implanted in their 

 constitution by the Creator, by which, independent of 

 instruction, observation, or experience, and without a 

 knowledge of tlie end in view, they are impelled to the 

 performance of certain actions tending to the well-being 

 of the individual and the preservation of the species : 

 and with this description, which is in fact merely a 

 confession of ignorance, we must, in the present state 

 of metaphysical science, content ourselves. 



I here say nothing of that supposed connexion of the 

 instinct of animals with their sensations, which has 

 been introduced into many definitions of this mysteri- 

 ous power, for two reasons. In the first place, this 

 definition merely sets the Morld upon the tortoise ; for 

 what do we know more than before about the nature of 

 instinct, when we have called it with Brown, a predis- 

 position to certain actions when certain sensations exist, 

 or with Tucker have ascribed it to the operation of 

 the senses, or to that internal feeling called appe- 

 tite ? But, secondly, this connexion of instinct with 

 bodily sensation, though probable enough in some in- 

 stances, is by no means generally evident. We may 



