3506 The Zoologist— May, 1873. 



and in some quarters to have been entirely misunderstood, I shall 

 endeavour to give an account of it in a manner more distinct than 

 has yet (I think) been done ; and to show that there is no good 

 ground for believing it to be irrational, as some have supposed, 

 and for scouting it as something beneath contempt. 



It has long been notorious to oologists that the eggs of the 

 cuckow are subject to very great variety in colour, and that a large 

 number of birds laying eggs of very different colours enjoy the 

 doubtful advantage of acting as foster-parents to the young cuckow. 

 Now the theory to which I refer is that " the egg of the cuckow is 

 approximately coloured and marked like those of the bird in whose 

 nest it is deposited, that it may be the less easily recognised by 

 foster-parents as a substituted one." 



This theory is old enough, for it was announced and criticised 

 nearly a hundred years ago by Salerne,* who, after mentioning 

 that he had seen two stonechats' nests, each containing eggs of 

 that bird, as well as a cuckow's (which was as blue as the others, 

 but twice [?] as large), goes on to say that he was assured by an 

 inhabitant of Sologne (a district in France to the south of Orleans), 

 that the cuckow's egg is always blue ; and then comes this remark- 

 able statement: — "As to thefassertion of another Solognot who 

 says that the hen cuckow lays its eggs precisely of the same colour 

 as those in the nest of which she makes use, it is an incompre- 

 hensible thing." Many of my readers will, I doubt not, be at once 

 inclined to agree with Salerne. 



Little attention seems to have been paid to this passage by suc- 

 ceeding naturalists ;t but in 1853 the same theory was prominently 

 and (I believe) independently brought forward by Dr. Baldamus, 

 then editor of ' Naumannia,' a German ornithological magazine, 

 now defunct ; so far as I know, however, itwas not until April, 1865, 

 that an article in the English ornithological journal, the ' Ibis,' by 

 Mr. Dawson Rowley, gave anything like an idea of it to the public 

 of this country. Some months later (I4th September) Mr. A. C- 

 Smith introduced the subject to the Wiltshire Archaeological and 



• L'bistoire naturelle, cclaii-cie clans line de ses parties priucipales, I'oniitliologie, 

 &c. raris; 1707, p. 42. 



+ MoutbeiDai-J (Hist. Nat. des Ois. vi. p. 300; meBtious it, i>ut I am not aware of 

 any one else who has done so, UutQ M. Yian in the ' Eevue ct JNIagasin de 

 Zoologie' for 1805 (p. 40), refen-ed to it, and from this reference I became ac- 

 quainted with it. 



