I02 Dariaiu and Romanes dealt with. 



" Let us suppose that the ancient progenitor of our 

 European cuckoo had the habits of the American 

 cuckoo, and that she occasionally laid an egg in 

 another bird's nest. If the old bird profited by this 

 occasional habit through being enabled to migrate 

 earlier or through any other cause ; or if the young 

 were made more vigorous by advantage taken of the 

 mistaken instinct of another species than when reared 

 by their own mother, encumbered, as she could hardly 

 fail to be, by having eggs and young of different ages 

 at the same time, then the old birds or the fostered 

 young would gain an advantage. And analogy would 

 lead us to believe that the young thus reared would 

 be apt to follow, by inheritance, the occasional and 

 aberrant habit of their mother, and in their turn 

 would be apt to lay their eggs in other birds' nests, 

 and thus be more successful in rearing their young. 

 By a continued process of this nature, I believe that 

 the strange instinct of our cuckoo has been gener- 

 ated." (pp. 212-213.) 



By the way, so many " may be's " and " would be 

 apts " do not seem to us quite so scientific as might 

 be. Again specially note the words I have put in 

 italics. 



Mistaken instinct ! How can an instinct, in the 

 sense here too obviously meant, be mistaken ? It is, 

 in view of its own intention, unerring, a fact which 

 Dr. A. Russel Wallace has duly recognised, and has 

 to fall back on failure of reasoning power. Either 

 this or the word " instinct " has really no proper 

 meaning. To nurse and feed an intruded alien to 

 the detriment of the creature's own young is surely 

 against instinct, and is to be accounted for by some- 



