44 INTRODUCTION. 



referrible to this property, I shall have compassed my 

 object, and shall have not illogically proved, that, if 

 such actions are not instinctive, they must be rational. 



Instinct, in a popular point of view, may be defined 

 to be, that property in animals ^'^ by which such actions 



purposes of communication, from wliat we observe in the watching 

 of sentinel birds, and in the instantaneous change in the flight and 

 extraordinary aerial evolutions of many congregated fowls, which 

 are performed M'ith such astonishing rapidity and precision, as at 

 once to convince us they are effected by a signal of sound, and not of 

 sight ; which latter the dense mass of the flock would prevent many 

 of them from observing. 



Presuming on the authority of Locke, it has been further argued, 

 that the manifest deficiency in the organs connected with speech in 

 brutes, is an additional proof, not only that they have little oral com- 

 munication between themselves, but that they are, from this cause, 

 essentially inferior in their intellectual importance. Withont deny- 

 ing their inferiority, it may however be answered, that full or exten- 

 sive intonation of voice is not necessary to the existence, or even to 

 the individual importance, of an intellectual animal, as we witness 

 in the conventional language of the deaf and dumb among the 

 human. Neither, in fact, is it essentially necessary that the con- 

 ventional language of brutes should be communicated by the mouth. 

 In many insects we know it is performed wholly without the oral 

 organs ; in some, air is agitated to produce different sounds by 

 means of the wings ; in others, by a mechanism not unlike the pipes 

 of an organ ; while others, again, either strike on hard substances 

 with their antennte, or communicate by crossing these slender and 

 flexible organs over the same organs of those with whom they wish 

 to connnunicate. One cannot witness this mode of communication 

 without being struck with the similarity between it and the convey- 

 ance of sound to the perception of a deaf person, by speaking along 

 a plane surface in connection with the inner surface of the mouth. 



34- The instinctive principle is not confined to animals only; it 

 pervades and directs the first movements of all organized bodies. 

 Plants alter their course to seek the sun, or to imbibe a purer at- 

 mosphere. Others produce smprising phenomena in their attempts 

 to emerge from darkness into light ; and the roots of trees change 

 and rechange their direction in search of earth adapted to their 

 wants as often as the occasion requires it. 



