THE WAY LIFE BEGINS 45 



beak, claws, etc., are fairly well formed, and the chick is 

 ready to enter the last stage of its egg life, that of breaking 

 through the shell. (Figure VII.) 



How the Chick Breaks Through the Shell 



The chick has now exhausted its food supply and the time 

 has come to break through the shell. Toward the end of the 

 nineteenth day peeps may be heard as the young bird begins 

 the work of releasing itself. On the tip of the upper beak is 

 a horny knob called the 'egg-tooth' which may be seen on the 

 beaks of newly-hatched chicks. When lying within the shell 

 the chick's head is near the equator of the egg, and by rubbing 

 against the shell with its toothed beak, at the same time turn- 

 ing about in the egg, it wears a groove through the whole 

 circumference of the shell. The struggles of the chick finally 

 break the thin groove, and there emerges a completely formed, 

 well-equipped young fowl. (Figures VI, vii, vni.) Chicks must 

 have had a normal development and much vitality in order 

 to make their way out, for it is no easy task and the weak- 

 lings usually perish within the shell. 



Chicks Compared with the Young of Other Birds 



The domestic fowl belongs to the same order of birds as 

 the quail, pheasant, grouse and turkey. They are called 

 ground birds and their young are able to care for themselves 

 almost at once after hatching. Notwithstanding this, natural- 

 ists speak of them as lower and more coarsely organized than 

 the thrushes, doves, warbles, and other song-birds whose 

 young are hatched in a wholly helpless condition and are, 

 therefore, dependent upon their parents. This dependence 

 makes necessary a longer or shorter mating of the parents, 

 the establishment of the home or nest, and the continued care 

 of one or both parents. 



Although some birds are helpless at birth, and others quite 

 precocious or matured, all go through the same course of 

 development from the fertilized egg. The chick is chosen 

 only because the transformation of yolk into chick has long 

 been studied, and the incubating eggs are easily obtained. 



