PART II 

 HATCHING AND REARING 



CHAPTER VIII 



THE EGG 



THE hen's egg is a mass of cells and tissue of different 

 kinds, encased in a shell or protective coat. 



Function of the Egg. In all nature the egg is the repro- 

 ductive body, but the function of the hen's egg is twofold. 

 The fertile egg contains in its center, the germ, which, on 

 the application of heat, will develop into a young chick, 

 and also, surrounding the germ or embryo, the yolk or food 

 material which nourishes the embryo during its growth. 

 From a reproductive standpoint, the egg contains both the 

 chick and its food supply. The entire mass is encased in a 

 protective shell which retards evaporation, so the egg can 

 be kept a considerable time without injury. In addition to 

 its reproductive function, the egg is used by man for human 

 food, and because of the excellency of the food, and the 

 great demand for it, poultry keeping has become a matter 

 of great commercial importance. The egg of the domestic 

 fowl is not only large of size but highly nutritious, the pro- 

 tein in the egg being especially valuable and considerable 

 in amount. 



Structure of the Egg. The component parts of the egg 

 are the shell, the membranes, the albumen, and the yolk. 

 The shell is an outer envelope or case surrounding the egg 

 to protect its contents. It is largely composed of carbonate 

 of lime, which the bird secures by eating oyster shells, bone 

 and grit. Sometimes hens lay soft shelled eggs. This is 

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