Comtuter and Internet News Channel
For the metabolism and development of the embryo in the egg as the adult bird (or reptile), you need to inhale oxygen and take the product of metabolism is carbon dioxide.
The embryo of a mammal (e.g., human) develops inside the mother’s body and receives oxygen through a shared mother and circulatory system. Similarly, through the blood, the fetus excretes carbon dioxide, which enters the lungs of the mother and exhaled. The egg, however, is a separate structure and exchange of blood with the mother hen has not. How breathing chicken? The thing in the air between the bag under the shell are two membranes — outer and inner. The bag is formed when just demolished the egg cools, the yolk protein is reduced in size and under the shell there is a cavity. Through the pores in the shell there sucked the air outside. Then, around 7,000 and it is through them, gas exchange occurs between the bag inside the egg and the atmosphere. Warm carbon dioxide comes out, the cold air with oxygen is sucked inside.