INSTINCTS. 163 



selection may depend upon some analogy be- 

 tween the smell of these animal matters and 

 the yolk, which was for along time their food 

 in the egg. 



ORN. I find I must multiply examples. 

 Examine young ducks which have been hatch- 

 ed under a hen ; they no sooner quit the shell, 

 than they fly to their natural element, the 

 water, in spite of the great anxiety and terror 

 of their foster -parent, who in vain repeats that 

 sound to which her natural children are so obe- 

 dient. Being in the water, they seize insects 

 of every kind, which they can only know from 

 their instincts to be good for food ; and when 

 they are hatched in the May-fly season, they 

 pursue these large ephemerae with the greatest 

 avidity, and make them their favourite food. It 

 is impossible, I think, to explain these facts, 

 except by supposing, that they depend upon 

 feelings or desires in the animals developed 

 with their organs, which are not acquired, and 

 which are absolutely instinctive. I will mention 

 another instance. A friend of mine was tra- 

 velling in the interior of Ceylon ; on the banks 

 of a lake he saw some fragments of shells of 

 M 2 



