92 Instinct, 



may never have seen a winter. Those that sleep 

 in winter, simply prepare a nest. In both cases, In- 

 stinct supplements function. Migration from place 

 to place, as the supply of food changes, is the meth- 

 od of solving the same question for many birds. 

 Function thickens the coat of the animal for winter 

 This provision is just as needful as any thing In- 

 stinct can do, but Instinct is not burdened with any 

 thing that function can perform. All that relates 

 to providing food in the first instance is left to In- 

 stinct. That action of the system by which it lives 

 upon the fat stored up in the fall and the change 

 that takes place in hibernation by which the ex- 

 penditure of material is lessened, are certainly func- 

 tional changes. These are instinct-like provisions 

 of the system ; but the securing of the food in the 

 first instance was done by a principle that supple- 

 ments structure and function ; and this principle is 

 something entirely different from them, and some- 

 thing that no structure or function of the animal 

 system would suggest the existence of, except as we 

 have learned by observation that there always is in 

 the animal a directing power which we call Instinct, 

 to supplement the structure and function of organs 

 and thus to complete the work commenced in the 

 body. 



