130 Darwin and Romaiies dealt with. 



connect the two species in a still more intimate 

 manner than theoretical writers have supposed them 

 to be allied." " 



Then Mr. Blyth refers to domestic pigeons as 

 wanting to lay again before the former brood are 

 quite ready to leave the nest : in no case of birds that 

 I have set up to breed has this not frequently been 

 the case : canaries especially wishing to turn the 

 young brood out of the nest to lay in it again. 



Mr. Blyth, after having referred to the migratory 

 instinct of the common British swifts being so strong 

 that they will sometimes leave later broods to starve, 

 asks whether the instances referred to by Mr. Audubon 

 of eggs of the American piayas being found in other 

 bird's nests happened at a late period of the season. 

 This is a most important point, and if it has not 

 already been answered by American ornithologists, I 

 hope that it soon will be, to enable us to compare 

 more satisfactorily these American piayas with our 

 Canorus. 



Now, in view of all these facts, is it likely — the 

 least likely — that our cuckoos, w^hich had passed 

 through long processes of change and differentiation, 

 at length involving the complete dependence on others 

 for brooding the eggs, and much consequent risk and 

 loss, would cease, in view of the preservation of the 

 species, to produce so many eggs as it had done in 

 the days when it was like its American congeners in 

 the points wherein it now differs from them ? If the 

 preservation of the species is the one great end of the 

 breeding process, then it is clear that certain of the 

 modifications very gradually effected on the cuckoo 



* Quoted by E. Blyth, Asiatic Soc. Jl., 1S42, pp. 1206-7. 



