58 Breaking the Shell. 



by five or six hours, while stale eggs will always be behind 

 time. For the purpose of breaking the shell, the yet soft 

 beak of the chicken is furnished, just aI)ove the point of the 

 upper mandible, with a small, hard, horny scale, which, 

 from the position of the head, as Mr. Yarrell observes, is 

 brouofht in contact with the inner surface of the shell. 

 This scale may be always seen on the beaks of newly- 

 hatched chickens, but in the course of a short time ])eels 

 off. It should not be removed. The peculiar sound, in- 

 correctly called " tapping," so perceptible within the egg 

 about the nineteenth day of incubation, which was univer- 

 sally believed to be produced by the bill of the chick 

 striking against the shell in order to break it and effect 

 its release, has been incontestably proved, by the late Dr. 

 F. R. Horner, of Hull, in a paper read by him before the 

 British Association for the Advancement of Science, to be 

 a totally distinct sound, being nothing more than the 

 natural respiratory sound in the lungs of the young chick, 

 which first begins to breathe at that period. Of course 

 there is also an occasional sound made by the tapping of 

 the beak in endeavouring to break the shell. 



The time occupied in breaking the shell varies, according 

 to the strength of the chick, from one to three hours 

 usually, but extends sometimes to twenty-four, and even 

 more. ^' I have seen," says Reaumur, '^ chicks continue at 

 work for two days together ; some work incessantly, while 

 others take rest at intervals, according to their physical 

 strength. Some, I have observed, begin to break the shell 

 a great deal too soon ; for, be it observed, they ought, 

 before they make their exit, to have within them provision 

 enougli to serve for twenty-four hours Avithout taking food, 

 and for this purpose the unconsumed portion of the yolk 

 enters through the navel. The chick, indeed, which comes 

 out of the shell without taking up all the yolk is certain to 

 droop and die in a few^ days after it is hatched. The 

 assistance Avhich I have occasionally tried to give to several 

 of them, by way of completing their deliverance, has 

 afforded me an opportunity of observing those which had 

 begun to break their shells before this was accomplished ; 



