INTRODUCTION. 19 



some of the younger birds, however, still nest in the swamps. 

 Bees, taken to the Barbadoes, lose their instinct of storing 

 honey, because they find food enough all the year long in 

 the sugar canes, while those in Jamaica, where the rainy 

 season prevents them from flying out for several weeks, 

 keep their instinct (Perty, " On the Intellectual Life of 

 Animals," 1876, p. 41). 



People are wont to say of the cuckoo that its instinct 

 leads it to lay its eggs in strange nests. How comes it 

 then that the American cuckoo does not possess this instinct, 

 but sits on its own eggs ? or that there are also other birds 

 which sometimes or occasionally lay their eggs in strange 

 nests, in order to save themselves the trouble of sitting ? Or 

 what has instinct to do with it, when the ostrich, like many 

 other birds, leaves the business of hatching its eggs to the sun, 

 during the day, and only covers them with its body during 

 the cool of the night ? Or when the same bird, acting in 

 this way in Senegal, never leaves its eggs day or night at 

 the Cape of Good Hope, where the warmth of the air is 

 less ? Or when geese and ducks, in our moderate climate, 

 leave their eggs for awhile without any care, while the 

 same birds in the polar regions in such a case cover their 

 nests with feathers as a protection against the cold ? In a 

 similar way the Canadian muskrats, translated into a 

 wanner climate, cease to build their neat warm nests, and 

 content themselves with a mere hole in the ground. 



One of the very famous instincts is that of the honey bee, 

 building six-sided cells ; a propensity which, as will be 

 shown later, has been, evolved in the most natural way. 

 But that this is not unchangeable, is shown by the fact that 

 bees guide themselves by circumstances, and give the cells 

 another or an imperfect shape when insuperable obstacles 

 are in their way. Darwin has also often observed, that 

 cells which had to be built in a corner or in some incon- 

 venient place, were repeatedly pulled down and built up 

 again until the architect was satisfied. The examples of 

 the change and of the improvement by circumstances in the 

 building instinct and other tendencies a fact which is 

 utterly opposed to the conception of an instinct are so 

 numerous in the insect world that Blanchard, in his great 

 work on the changes and habits of insects (Paris 1868) 

 wrote : 



