YOUNG CUCKOO. 137 



trusion often occasions some discomposure ; for 

 the hedge-warbler, at intervals, while she is sitting, 

 has been observed to throw out some of her own 

 eggs, or otherwise injures them so that they be- 

 come addled. " But/' says Dr. Jenner, " I have 

 never seen the bird either throw out or injure the 

 egg of the cuckoo. " 



The course of events from this time forward is 

 well illustrated in one of the examples given by 

 Dr. Jenner. A hedge-sparrow built her nest in a 

 hawthorn bush in a timber yard. After she had 

 laid two eggs, a cuckoo dropped in a third. The 

 sparrow continued laying until she had laid five, 

 her usual number, as if nothing had occurred, and 

 then began to incubate. On inspecting the nest 

 a few days subsequently, the period of the incu- 

 bation of the cuckoo's egg being about fourteen 

 days, it was found that the young cuckoo was the 

 sole occupant of the nest. Underneath was a sad 

 spectacle ! One of the young hedge-sparrows lay 

 on the cold ground quite dead, and it was only 

 the fibrous materials surrounding the interior of 

 the nest which, arresting the downfal of an egg, 

 saved the life of another ; for on examining it, one 

 end was found a little chipped, and the young 



