Not only one Instinct defeated. 191 



for its vast importance), to the utter indifference with 

 which the hen hedge-sparrow, as Mr. John Hancock 

 so circumstantially tells, sat and saw one of her own 

 progeny edged over the side of the nest by the young 

 cuckoo. Mr. John Craig notes precisely the same 

 thing. This shows such an extraordinary departure 

 from all that we have hitherto regarded as parental 

 instinct in birds and highly developed mammals alike, 

 that it is not hard for us to believe that in some cases 

 the passive procedure under such an outrage may 

 become active, and that as Jenner said long ago, the 

 foster-parents may " themselves sometimes turn out 

 unhatched eggs from the nest after the young cuckoo 

 is hatched." 



One extraordinary element in the matter is, that 

 this big and unwieldly nestling, which had shown 

 such unexampled powers in throwing out eggs and 

 young from the nest when but a few days old, be- 

 comes, in a sense, the more dependent and helpless 

 as he outgrows the nest, and when he has found 

 strength to leave it, keeps up an endless demand on 

 the victimised birds for weeks : so that they are hin- 

 dered from breeding again, when they otherwise 

 would certainly do so. Thus you have not only one 

 ordinary instinct or two overborne and superseded by 

 what seem unnatural and extraordinary instincts, but 

 here is another. If in the victimised birds this latter 

 instinct was not overcome, the young cuckoo would 

 even then fall a victim to hunger : if the parent 

 victimised birds returned on their true instinct, the 

 real end of all the cuckoo's endeavours would be 

 defeated — the young would not survive. But that 

 through such a long period you should find birds of 



