74 THE INFANCY OF ANIMALS 



this chamber is of unknown function, but it is significant 

 in this connection that it gradually disappears at the 

 end of the nesthng period, hardly a trace remaining in 

 the adult. But whatever its origin, this envelope most 

 effectually serves its purpose : the whole mass may be 

 lifted up in the fingers without soiling them. 



The parent birds are most particular in hunting for 

 these capsules of faecal matter at the bottom of the nest 

 whenever they come to feed the young ; and Mr. H. EUot 

 Howard, in his wonderful book on the " British Warblers," 

 tells us that among these birds at any rate, it is the custom 

 of one or other of the parents, in the absence of the ex- 

 pected matter, to tap the anus of the young bird just 

 fed as a reminder, so to speak, of a duty to be performed. 

 As soon as the capsule is found, it is seized by the beak, 

 borne away from the nest and dropped, but at a safe dis- 

 tance, so as not to reveal the presence of the nursery to 

 possible enemies. In many cases, however, as among the 

 thrushes for instance, this bolus is commonly swallowed, 

 and this not by accident, but by intent. As the young 

 grow and gather strength, however, they relieve the 

 parents of this work of sanitation by raising the tail over 

 the edge of the nest and then expelling the faeces. 



In a number of species, however, no such faecal invest- 

 ments are formed, and, as a consequence, in a short time 

 the area around the actual nest becomes indescribably filthy, 

 as for example in the case of the hoopoe and the kingfisher. 

 But even when the faeces are not protected a certain 

 amount of sanitation is observed : as for example in the 

 case of the golden eagle, which periodically removes the 

 castings of its offspring — the bones, fur and feathers, 

 matted into a ball or " pellet," and thrown out by the 

 mouth — bones and other broken remains of feasts, and 



