120 HUMBLE CREATURES. 



where certain sensations exist/' is passed over very 

 lightly by this authority ; and he shows that, although 

 some of the actions of insects are attributahle to the 

 effect of appetites, there are others that can certainly 

 not be thus accounted for. 



And then, having combated these various theories 

 or methods by which instinct is defined, and rejected 

 others as absurd and unworthy of consideration, Mr. 

 Spence sums up his observations by characterizing 

 this quality in the lower animals as " those unknown 

 faculties implanted in their constitution by the Creator, 

 by which, independent of instruction, observation, or 

 experience, and without a knowledge of the 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." 



Having thus endeavoured to cull from the valuable 

 work in question the four defi.nitions of iastiact most 

 at variance with each other, we wiH now turn to the 

 pages of another able authority, namely Dr. Car- 

 penter, in whose treatise on Comparative Physiology 

 we find it stated as his opinion, that the instinctive 

 actions of animals are " performed (as it would appear) 

 in immediate respondence to certain sensations with- 

 out any intentional adaptation of means to ends on the 

 part of the iadividual*.-" 



His view of instinct appears to be, that it is a pro- 

 pensity or " propensities called into action by sensa- 

 tions," and accords, therefore, to some extent with 

 * ' Comparative Physiology,' 4tli edit. p. 693. 



