302 



THE LIFE OF A BLRD. 



events the fracture extends round the circum- 

 ference of the shell, although it is impossible to 

 account precisely for the manner in which this is 

 effected. A certain degree of movement appears 

 to be possessed by the chick, which is probably 

 assisted by the motion given by the hen to her 

 eggs on leaving them and re- 

 turning to them. In artificial 

 incubation this is effected by 

 the attendants. It is not im- 

 probable also that by con- 

 stantly thrusting against the 

 side of the shell with its bill, 

 the body of the chick may be 

 slightly pushed round. The 

 fracture is complete, and the 

 egg then presents the appearance represented in 

 the cut. 



The time occupied in this labour varies con- 

 siderably. Some, as we are informed by Reaumur, 

 are able to come out of their shell in an hour after 

 they have commenced chipping ; others not for 

 t\vo or three hours ; most commonly it is the task 

 of half-a-day. Sometimes it extends over two 

 days. This variation depends on the variable 



