HEREDITARY INSTINCT. 259 



PHYS. These fish, then, have the same 

 habits as our English salmons and trouts? 



HAL. The principle to which I have re- 

 ferred in two former conversations must be 

 general, though it has seemed to me, that they 

 lost this memory sooner than the fish of our 

 English rivers, where fly fishing is common. 

 This, however, may be fancy, yet I have re- 

 ferred it to a kind of hereditary disposition, 

 which has been formed and transmitted from 

 their progenitors. 



PHYS. However strange it may appear, 

 I can believe this. When the early voyagers 

 discovered new islands, the birds upon them 

 were quite tame, and easily killed by sticks 

 and stones, being fearless of man ; but they 

 soon learned to know their enemy, and this 

 newly acquired sagacity was possessed by 

 their offspring, who had never seen a man. 

 Wild and domesticated ducks are, in fact, 

 from the same original type : it is only ne- 

 cessary to compare them, when hatched to- 

 gether under a hen, to be convinced of the 

 principle of the hereditary transmission of 

 habits, the wild young ones instantly fly 

 s 2 



