Hatching with Incubators 147 



The Growth of the Embyro. — The growth of the 

 chicken within the egg is remarkably rapid. At 

 the end of the second day many important struc- 

 tures, especially those about the head, are visible 

 to expert eyes. 



In three days a new membrane forms inside the 

 shell membranes. This new membrane serves as 

 lungs to the growing chick. It has many hairlike 

 sacks, which absorb the liquid contents of the egg, 

 and turn them into blood. Contained in these 

 tiny vessels, the blood is exposed to oxygen that 

 enters through the pores in the shell. It is then 

 returned to the center of life, and circulation is 

 estabHshed. 



By the sixth day the elements of the chief parts 

 are formed, and assume such size that the growing 

 embryo may readily be seen through the shell 

 when the egg is held to a strong light. 



By the ninth day the head is clearly visible, the 

 beak and claws are formed, and the feathers 

 appear. Four days later the hard, bony structures 

 develop, and the chick is equipped with all impor- 

 tant organs. 



Up to the fourteenth day the chick has been 

 lying across the egg. Then it turns, so that the 



