THE EGG 99 



up. During the breeding or laying season this tube is very 

 large and nearly fills the cavity of the body. When the hen 

 ceases to lay it shrivels up and occupies but little space. 

 The opening of the oviduct into which the yolk falls is large 

 and funnel-shaped. The upper part supplies the thickened, 

 gelatinous albumen; the next two folds furnish the albumen 

 which forms the two thinner layers; the last layer is very 

 watery. As the egg mass passes through the oviduct, it 

 revolves around and around, and this rotary motion gives 

 the egg its elliptical shape. It is during this stage of forma- 

 tion that the thick cords within the yolk are formed. These 

 cords have a knotted, twisted appearance due to the revolu- 

 tion of the egg. 



Contraction of the walls of the oviduct force the egg 

 through the tube. The secretion of albumen is caused by 

 the stimulating effect of the passage of the egg. Just before 

 the egg leaves the oviduct, it passes through a short, thick- 

 walled portion, which secretes the fluid that forms the shell. 

 The shell is put on as a liquid coating, which immediately 

 hardens, and the perfect egg passes into an enlarged sac, 

 called the cloaca, and here it remains imtil the hen lays it 

 in the nest. It takes about twenty-four hours for the egg 

 mass to pass through the oviduct. When hens are in heavy 

 lay, there are often two eggs in the oviduct, one just enter- 

 ing, while the other is receiving its shell. 



Malformed or misshapen eggs are usually due to either 

 the bird's being too fat, or to a diseased condition of the 

 oviduct. A double yolked egg, an egg within an egg, small 

 or peculiarly shaped eggs are frequently seen. 



The Egg as Food. — From the standpoint of human food, 

 the egg is very valuable. It is similar in composition to the 

 adult bird, but is more concentrated. The solid matter in 

 an egg, exclusive of the shell, contains 50 per cent of protein 

 or nitrogenous material. There is also nearly 40 per cent 

 of fat, and three per cent of ash or mineral matter. The 



