A YOUNG CUCKOO 63 



the members of each laying a type of egg distinct in its 

 style and coloration from the eggs laid by members 

 of any other clan. Each of these types is held to 

 approximate in its style and coloration to the eggs 

 laid by some particular species of the birds that act 

 as foster-parents to the young parasite, so that there 

 is said to be a gens of Cuckoos that lay eggs resem- 

 bling those of the Meadow-pipit and place them 

 regularly in Meadow-pipits' nests; and so on for other 

 species. Heredity is called in to account for the con- 

 tinuance from generation to generation of each clan 

 of Cuckoos with its respective foster-species ; and 

 Natural Selection to explain the assimilation of the 

 type of egg laid by each clan to that of its particular 

 foster-species, through the elimination of those 

 members whose eggs failed to show a sufficient 

 degree of resemblance. Thus, Professor Newton 

 writes : " That there is a reasonable possibility of each 

 Cuckoo most commonly putting her eggs in the nest 

 of the same species of bird, and of this habit being 

 transmitted to her posterity, does not seem to be a 

 very violent supposition. Without attributing any 

 wonderful sagacity to her, it does not seem 

 unlikely that the Cuckoo which had once successfully 

 foisted her egg on a Reed-wren or a Titlark should 

 again seek for another Reed-wren's or Titlark's nest 

 (as the case may be) when she had another egg to 

 dispose of, and that she should continue her practice 



from one season to another Such a habit 



could hardly fail to become hereditary, so that the 

 daughter of a Cuckoo which always put her egg into 

 a Reed-wren's, Titlark's, or Wagtail's nest would do 

 as did her mother." 



