CHAPTER XIV 



METHODS OF HATCHING CHICKENS 



Structure of the Egg. The principal parts of the egg 

 are, in the order of their growth, the yolk, the albumin or 

 white, and the shell. The yolk is built up carefully layer 

 upon layer and requires about two weeks to develop from 

 the size of a pea to the full-sized yolk. It contains the 

 blastoderm or germ cell, which may be seen as a white speck 

 one-eighth inch in diameter on its upper surface. This 

 speck enlarges when the egg is kept in a warm room or in 

 a high temperature. The blastoderm, as Lillie says, "is 

 the living part of the egg from which the chick embryo and 

 all its parts are derived." There is more or less develop- 

 ment of the embryo of a fertile egg before it is laid, due 

 to the body temperature of the hen. Should the egg be 

 retained in the uterus, as sometimes happens, a day or 

 two before being laid the development may proceed so far 

 that the egg will be unfit for eating. Retarded laying, 

 however, seldom happens. The yolk furnishes the embryo 

 a large part of its nutriment, and the unassimilated part 

 of the yolk furnishes the chick food for several days after 

 hatching. 



The Albumin in different layers surrounds the yolk. 

 Close to the yolk there is a dense layer which forms at each 

 end of the egg two spirally twisted cords. These are called 

 the chalazae, the apparent function of which is to hold the 

 yolk in place. The albumin is a protection for the germ or 

 blastoderm. It keeps it from coming in contact with the 

 shell and lessens the force or effect of jarring. Another 

 function of the albumin is to prevent the entrance of bac- 



281 



