The Zoologist— March, 1868. 1115 



The next question examined is, " whether the same hen cuckoo lays 

 eggs of the same colour and markings only, and so is she limited to 

 the nests of but one species ? or else, does the same individual lay 

 eggs of different colour and markings, according to the character of 

 the eggs amongst which her own will be intruded ? " Both these 

 theories have their advocates; those in favour of the last view- 

 advancing the hypothesis that the sight of the eggs lying in the nest 

 has such an influence on the hen which is just about to lay, that the 

 egg which is ready to be laid assumes the colour and markings of 

 those before her, and for this physiological reasons are adduced, and 

 analogies, not forgetting the well-known and successful experiments of 

 the patriarch Jacob.* But Dr. Baldamus rejects this opinion, and 

 contends for the other view (viz. that the same cuckoo lays eggs of 

 one colour and markings only, and so is limited to the nests of but oue 

 species) : and this he proves by personal experience and Observation ; 

 by the fact that he has found two differently marked cuckoo's eggs in 

 one nest; that he has also found similarly marked eggs laid by one 

 and the same cuckoo, in the nests of different species ; and that he has 

 found cuckoo's eggs (though rarely) in such nests as have not yet 

 received any eggs of the owner,t in which case the cuckoo is without 

 any pattern of a fixed form of colour for its egg. All these points in 

 the argument are very carefully worked out at considerable length, and 

 a large array of proofs and instances brought forward to support his 

 views; and then our author deduces the conclusion that all experience 

 hitherto known declares in favour of his assertion " that every cuckoo 

 lays eggs of one colouring only, and consequently (as a general rule) 

 lays only in the nest of one species ;" and he sums up his argument as 

 follows: — "Every pair or rather each individual cuckoo is endowed 

 with the instinct to lay its eggs in the nests of some one species of 

 birds, which are fit to act the part of foster-parents; so in order that 

 these latter may the less readily observe the strange egg, it is found to 

 be of similar colouring to their own ; and for the same reasons it is 

 also so disproportionably small. Then every pair of cuckoos seeks its 

 old district, or that spot where it breeds, just as all other birds do. J 

 Here it generally finds those species of insectivorous birds which it 

 requires for its peculiar circumstances: but assuredly they are not 

 always in the necessary numbers, or perhaps they may for some cause 



* Genesis, chap. xxx. 37, et seq. 



f This is corroborated in the ' Naturalist ' for 1852, p. 33. 



| Blylh's edition of White's ' Selborne,' p. 78. 



