Intervals between Layings. iii 



from a dormer attic window, four days, owing to cold 

 and frost passed between the third and the fourth ; 

 and Mr. Robert Read, a most reliable authority, 

 assures us that he once found a blackbird's nest at 

 Blackheath, very early in the spring, in wbich the 

 bird had laid a single egg. A spell of firost and snow 

 super\-ened, and no more eggs were deposited for a 

 fortnight, when mild weather once more set in and 

 two more eggs were laid precisely similar to the first 

 and evidently by the same bird. There are certain 

 general rules about this point connected with species 

 of birds, but the exceptions are the most interesting 

 in all cases to observe and study ; leading to the idea 

 of resource, adaptation and contrivances manifold, 

 so that there is in no case the absolutely assured 

 uniformity Mr. Darwin assumes. All this Mr. Darwin 

 would on his principle here, in ornithology, wipe out 

 — a strange thing for him to do : for here, in this very 

 bird, we have, perhaps, the most remarkable hints of 

 his own favourite evolution and natural selection ! 

 Truly the race is not always to the swift, nor the 

 battle to the strong, nor even the power in the case of 

 great observers to see the point. This much in our 

 own favour. 



Mr. Darwin in the sixth edition of the Origin of 

 Species also, rather maladroitly says : 



•' I have lately heard from Dr. Merrell, of Iowa, 

 that he once found in Illinois a yoimg cuckoo together 

 ^^•ith a young jay in the nest of a blue jay (Garruliis 

 cri status) ; and as both were nearly fully feathered, 

 there could be no mistake in their identification." 



Here the fact of the two young birds of diflferent 

 species together has a significance as to differentiation 

 at which he does not even glance. 



