NATURAL HISTORY. 



207 



" Tlxe uuin who can see without pleasure a hen gather her 

 chicksns u-.ider her wing, or the train of ducklings follow their 

 parent into the i^ond, is like him who has no music in his 

 soul." Kxox. 



chick whilst it is in the shell ; the yolk is embraced in the body' 

 of the chick when excluded from the shell, and a duct leads from 

 the membrane enclosing this mass of nutriment into the first 

 intestine. Thus the chick is nourished, not only whilst enclosed 

 in the shell, but also during its first feeble existence. 



955. When we hold an egg steadily, and chip it at the upper part, we find the 

 yolk close to the shell, and on the upper surface a pale vesicle, 3, which contains the 



embryo chick. When the hen sits, the heat of her 

 body developes the action of the living principle in 

 the emhryo, and on the second and third day a little 

 zone of blood-vessels, 4, 4, 4, appears? ; these vessels 

 run towards the embryo, and carry nourishment to 

 it ; and day by day we may watch its sensible 

 growth. From the delicacy of this action, we may 

 perceive how necessary it is that the embryo af an 

 early period should be close to the breast of the hen, 

 and not at the cold bottom of the nest. We shall 

 now see how it is accomplished The yolk is a globe 

 of nutritious matter, and the little vesicle with the 

 embryo is involved in the surrounding membrane, 

 and consequently is at the surface of the globe. If 

 this globe had the axis of its revolution in the 



centre, it would not move with the change of the position of the egg. But the axis 

 being below the centre, it must turn round with every change in the position of the 

 egg, whether the globe be heavier or lighter than the suiTounding white : were it 

 heavier, it would revolve so as to bring the embryo to the lower part of the shell 

 were it lighter, to the upper part of the shell. It is lighter, and the matter stands 

 thus : The yolk is, as it were, anchored at two points, and the attachments being 

 below the centre, and the yolk being lighter than the surrounding white, it 

 revolves like a buoy, and the vesicle containing the embryo is thus kept 

 always uppermost.* 



956. Why has the young chick a hard scaly substance upon 

 its beak? 



This curious provision is designed to assist the young bird in 

 breaking the shell , at a time when its bill is too soft for 

 that purpose. 



The manner in which the young chick breaks the egg is one of 



Paley's " Natural Theology." 

 13* 



