PRAIRIE FARMER'S POULTRY BOOK 



food from which all the structures of the animal organism can 

 be produced — bone, muscle, nerve, and connective tissue. 



Origin of an Egg 



Every animal organism is produced from an egg, that is, 

 from a primordial cell, which corresponds to the initial cell 

 from which every poultry egg is derived. The ovary of a hen 

 contains from 800 to 7000 egg possibilities. An examination 

 in the laying season shows the yolks, or ovules, in various 

 stages of development, from the smallest, which are merely 

 microscopic points, oocytes, to the fully formed yolk ready to 

 be discharged into the oviduct. 



Not all of these undeveloped ovules ripen into mature eggs. 

 The average annual production of a farm hen is not more than 

 70 eggs. The poultry breeder is content to secure 300 to 400 

 eggs from each hen in his flock, yet hens have been known to 

 produce more than 1,000 eggs in a lifetime. 



The Poultry Department of Purdue University has pro- 

 duced a hen, Joan of Arc, which has laid 1,064 eggs. 



The Experiment Station of Oregon Agricultural College 

 has developed twenty hens with trap-nest records of more than 

 1,000 eggs each. The highest record was made by a hybrid hen 

 containing Barred Rock and White Leghorn blood. In her 

 ninth year she died leaving a total production record of 1,335 

 eggs. Undoubtedly this is the world's highest egg-record for 

 an individual hen. 



How is an Egg Formed? 



The ovary lies in a delicate membrane known as the ovi-sac. 

 The ovi-sac surrounding each developing yolk is generally 

 known as the follicle. Under the stimulus of suitable food, 

 exercise and warmth, the initial cells from which the yolks are 

 formed begin to grow. As they develop, successive layers of 

 albumen are deposited. This material is furnished from the 

 blood through the blood vessels of the follicle. Immediately 

 surrounding the yolk a delicate membrane is formed known as 

 the vitelline membrane. 



Upon the surface of the yolk lies the germinal vesicle. This 

 is the living germ cell with which the sperm cell must fuse to 

 produce the embryonic cell from which the embryonic chick 

 is developed. When the yolk is ripe, or fully matured, the 



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