458 Letters, Extracts, and Notes. [Ibis, 



nest some clays after laying, is that it postulates considerable 

 memory for the Cuckoo ; but, after all, the possession of 

 such a faculty would not be more remarkable than the fact 

 that two Cuckoo's eggs so rarely occur in the same nest, 

 for if the bird can remember not to lay twice in the same 

 place, why should she not remember-where to put her egg 

 the day after laying ? 



Regarding Major Meiklejohn's remarks on the subsequent 

 interest of the Cuckoo in her &g^, one might perhaps make 

 the criticisms that in the first case the Cuckoo inspecting 

 the nest may not liave been the same bird. In that of the 

 White Wagtail there is no evidence that the young Cuckoo, 

 failing to eject the young, did not smother them, and that 

 they were then, as sometimes happened, removed by their 

 own parents. Finally, may not the last instance be explained 

 by supposing that the presence of an e^^, even though not 

 her own, excited the Hedge- Sparrow to incubate ? Normally 

 the stimulus to incubation seems to be internal — from the 

 genital organs probably ; but as I have known a Greenfinch, 

 and also a Twite, begin to sit on their first e^g and lay others 

 subsequently, I believe that abnormally the stimulus may be 

 external, and be due possibly to the sensation of eggs under 

 the breast. 



Yours faithfully, 



London Unit S.W.H. Maud D. Haviland, 



Odessa. H.M.B.O.U. 



May 15, 1917. 



Sir, — In Major Meiklejohn's valuable article on the 

 " Breeding-habits of the Cuckoo " he quotes Dr. Rev 

 (p. 193) as asserting that eggs laid in the nest oi Accentor 

 modidaris apparently never resemble those of the foster- 

 parent. Again (p. 202) he states on his own authority : — 

 " In Britain the Hedge-Sparrow is frequently selected as 

 foster-parent, and the eggs are, as a rule, successfully 

 hatched. Yet Cuckoos' eggs found in the nests of this 

 species are never blue." 



When selecting varieties of eggs for illustration in 



