Qnestio)is needing Answers. 147 



experience at all, rejects an egg which to certain 

 senses must in the dark seem very much like its own, 

 or the coots rejecting the ducks' eggs and deserting 

 the nest. 



In one word. Nature has here armed the wood- 

 pecker and the coot with a wonderful instinct against 

 brooding alien eggs — an instinct, by the way, which 

 is seldom or never called out : while Nature has 

 failed — absolutely failed — to arm many small birds 

 with any such instinct as regards cuckoos' eggs. 

 Why is this ? Mr. Romanes argued with all his 

 might that the deposition of cuckoos' eggs was " com- 

 paratively so exceedingly rare an event " that Nature 

 had not deemed it worth her while to call out a 

 counteracting instinct, mark you ; but here is a puzzle 

 which has three branches : (i) she has, apparently, 

 armed the woodpecker and coot with this instinct 

 without any great call to do so — deposition of alien 

 eggs in their nests being certainly "an exceedingly 

 rare event ; " and she has not so armed many birds 

 where there is assuredly the very greatest call : for (2) 

 the deposition of cuckoos' eggs is not, either here or in 

 foreign countries, "an exceedingly rare event" — 

 whole species being much reduced on this very ac- 

 count ; so that Mr. Romanes was either writing in 

 ignorance, or writing so from design, helplessly. The 

 problem remains : Why has Nature bestowed on 

 certain birds so strong an instinct, which is seldom or 

 never called into exercise, and refrained from bestow- 

 ing it where, for preservation and increase even of 

 the species, it was so much needed ; and (3) how is it 

 that a few species of birds, more and more in all 

 countries, have come, and are coming, to reject or to 

 build over the cuckoo's egg ? 



