THE CUCKOO 477 



little short of supernatural ? It would he absurd to suppose that the 

 I'ird exercises any foresight in the matter; that it knows its ehances 

 of survival dopnnd upon its receiving the undivided attention of it* 

 foster-parents. This is the effect of its action, but the came must be 

 some immediate and very potent stimulus. The only account which 

 clearly indicates what this stimulus may be is that of Mr. W. H. 

 Hudson in his Hampshire Days (p. 16), by far the most interesting and 

 important written since the days of Jenner. 



Mr. Hudson found a robin's nest containing four eggs, one being 

 a cuckoo's. On the afternoon of May 27 the young cuckoo hatched 

 out At 8 A.M. on the 20th one robin's egg had been ejected, a newly 

 I " .1 1 1 young robin and the third egg being still in the nest " The 

 cuckoo occupied the middle of the deep, cup-shaped nest, and his 

 broad back, hollow in the middle, formed a sort of false bottom ; but 

 there was a small space between the bird's sides and the nest, and in 

 this space or interstice the one unhatched egg that still remained and 

 the young robin were lying." The cuckoo appeared to be very sensi- 

 tive to the pressure of these two bodies against his sides ; of the egg 

 especially, which was hard and unyielding; "he was continually 

 moving, jerking and wriggling his lumpish body this way and that, as 

 if to get away from the contact At intervals this irritation would 

 reach its culminating point, and a series of mechanical movements 

 would begin, all working blindly but as surely towards the end as if 

 some devilish intelligence animated the seemingly helpless infant 

 parasite." In a space of eight minutes he made four separate efforts 

 to get rid of the egg, but as he pushed or carried it up the wrong or 

 upper side of the nest, it rolled back each time. 



" The process in each case was as follows : The pressure of the 

 egg against the cuckoo's side, as I have laid, was a constant irritation ; 

 (nit the irritability varied in degree in different parts of the body. On 

 the under parts it scarcely existed; its seat was chiefly on the upper 

 surface, beginning at the sides and increasing towards the centre, and 

 was i:reateM in the hollow of the hack. When, in inovin-. the 



