106 A PHILOSOPHER WITH NATURE 



difference almost to suggest a doubt whether they 

 are really speaking of the egg of the same bird. 



Closely associated with this question of the unusual 

 variation in the appearance and size of the cuckoo's 

 egg is that of the character of the nest in which 

 it is laid. Formerly, before the habits of the cuckoo 

 had been made the subject of such close study, the 

 prevailing idea was that the bird sought out a con- 

 venient nest, apparently at random, and laid an 

 egg in it in the absence of the owner. More sys- 

 tematic observation has, however, revealed that the 

 cuckoo's meanness has more method in it, and 

 method too which is apparently most skilfully 

 devised to attain certain ends. 



A great number of authentic observations, made 

 in a variety of places, appear to have established 

 it as a fact beyond doubt that the eggs of the cuckoo 

 are as a rule deposited in the nests of birds whose 

 eggs approximate both in size and appearance to the 

 strange egg placed among them. The view pre- 

 viously held that the cuckoo actually laid her egg 

 in the chosen nest has been considerably modified 

 by observations both in this country and on the 

 Continent. It seems still probable that the cuckoo 

 sometimes lays in the nest, particularly when it is 

 open and conveniently situated, but the general 

 habit of the bird would appear to be to lay her egg 

 on the ground first and then to take it in her bill 

 and deposit it in the selected nest. 



This method of depositing the egg, taken in 

 connection with the acknowledged fact of the vari- 

 ability of the cuckoo's eggs and their general approxi- 

 mation in appearance to the eggs with which they 

 are placed, has led to the formulation of two theories 



