290 Cuculidce. 



thrown, by laying it before one whose authority in such matters is 

 of European reputation, and who would have carried conviction 

 in its favour, or the contrary, by any decided opinion upon it he 

 expressed. But when, in answer to my inquiries, the late Mr. 

 Charles Darwin most kindly replied ' that he had no sufficient 

 information on the point, such as would warrant him to pronounce 

 any dogmatic judgment on it,' I thought it not altogether worth- 

 less. I should, however, in candour own that Mr. Darwin added, 

 * My impression is that differences of food would not produce the 

 effects which you suppose possible ; and that impression is derived 

 chiefly from there being hardly any evidence of variations being 

 due to slight differences in the nature of the food.' Mr. Darwin 

 then proceeded to give me several interesting examples of change 

 of colour in plumage, and especially called my attention to the 

 paper (in Proc. Zool. Soc.) on the Australian Cuckoos by Mr. 

 Kamsay, where that gentleman 'states that two of the species, 

 when they lay their eggs in an open nest, manifest a decided 

 preference for nests containing eggs similar to their own in 

 colour.' 



Many years have elapsed since the controversy was carried on 

 with reference to the colouring of the Cuckoo's egg. Several 

 leading ornithologists, Professor Newton amongst them, declared 

 that a well-authenticated blue Cuckoo's egg, somewhat similar to 

 that of the hedge sparrow, was wanting to complete the case as 

 enunciated by Dr. Baldamus ; and now in addition to those put 

 forth by Dr. Baldamus, and Dr. Hey, and some instances which I 

 and others adduced, Mr. Seebohm has published in his excellent 

 work on British Birds a whole plate of Cuckoos' eggs, amongst 

 which are two coloured blue, like those of the hedge accentor or 

 redstart. But I doubt if the ornithological world of England is 

 yet convinced. Perhaps we have not yet arrived at a full under- 

 standing of this, and of some other interesting details on the life 

 and economy of the Cuckoo, which still maintains in some 

 respects its character as a mysterious creature. I should not, 

 however, close this account without observing that the only other 

 species of Cuckoo with which I am familiar is the ' Great Spotted 



