Necessity of Observation. 123 



Hence might be supposed to give ; but the ability 

 being needed before it could be gained from expe- 

 rience, it appears as part of that outfit with which 

 the animal is sent into the world. But the princi- 

 ples of action in many of these cases, are of such a 

 nature that there is nothing in the organization of 

 the animal to suggest their existence. We learn 

 of their existence only by observation. There is 

 nothing in the structure of birds to indicate to us 

 with any certainty where they will build, or the 

 form of their nests. We know that the fowl gives 

 the cry of danger at the sight of the hawk, and that 

 its young seek cover at the alarm, because we have 

 seen the frightened brood thus guided by Instinct. 

 We readily see the wisdom of the thing, but it is 

 impossible to learn from the structure of the ani- 

 mal that it will perform these particular acts, as we 

 could infer from the talon and beak of a new spe- 

 cies of hawk that it would live on flesh, or from the 

 structure of the web-foot that its possessor would 

 seek the water. 



Instincts that minister directly to the appetites, 

 are common to all animals as an absolute necessity 

 to them. They must act promptly, or individuals 

 must perish, until the species disappears. 



Instincts that protect animals from their most 

 fatal enemies are common to many species, ready 

 to spring into action the instant the enemy is per- 

 ceived, even for the first time. And such an In- 

 stinct seems to be almost as essential to the preser- 

 vation of some species, as are the Instincts that 

 minister to the appetites. 



