THE EGG 97 



egg, and surrounding the yolk is a membrane to keep it in 

 place. The yolk is rich in fat. It is usually round and 

 yellow. Its function is to nourish the developing embryo. 

 When the chick begins to grow, a number of blood-vessels 

 develop which feed on and absorb the yolk. In the upper 

 part of the yolk is a little indentation or hollow, in which 

 the little chicken develops during the incubation period. 

 Sometimes yolks are a very light yellow, at other times very 

 dark; this color is materially affected by the kind of feed 

 given. That portion of the yolk which still remains when the 

 chick is ready to hatch is absorbed into the chick's body, 

 and furnishes its nourishment for the first day or two. 



Formation of the Egg. — The egg is the product of the 

 reproductive organs of the female, which are quite complex, 

 and consist of the ovary and the oviduct. Since the young 

 chick develops outside of the mother's body, the egg also 

 must be complicated in structure in order to protect and 

 nourish the embryo. 



In the hen the ovary Ues in the center of the cavity of the 

 body, and is attached to the back bone, and closely resembles 

 a bunch of grapes. The small yellow yolks or ovules vary 

 in size from that of a pin head to that of a walnut, and each 

 is attached to the ovary by a stem or string. The mother 

 hen has in her body at maturity a certain number of ova 

 or very small yolks, and the rapidity of their development 

 depends largely upon the care and feed given her. The 

 yolks are developed from the surplus feed consumed which 

 is not needed for her growth or maintenance. As the feed 

 is deposited in the yolks, they grow and mature, one being 

 always a little ahead of the others. When a yolk is fully 

 grown, the sac or pouch which encloses it breaks in its middle 

 line, and the ovum drops into an open tube, and after the 

 yolk has fallen what remains of the sac dries up and dis- 

 appears. In a day or two another yolk reaches maturity, 

 and goes through the same process. The rapidity of develop- 



