EXERCISE 80 

 A STUDY OF THE EGG 1 



Object. To study the egg and become familiar with its 

 parts. 



Explanation. In structure the egg consists of three 

 principal parts : the shell, white, and yolk. The eggshell is 

 a structure composed principally of lime for the purpose of 

 protecting the egg. Just under the shell are two thin, tough 

 membranes that serve further to protect the egg and prevent 

 its drying out too rapidly. Near the larger end of the egg 

 is usually found an air space. This air space is compara- 

 tively small when the egg is fresh, but becomes larger as the 

 egg grows older, due to the drying out and shrinking of the 

 white and yolk of the egg. The size of the air space serves as 

 a means of determining the age of the egg. The air space 

 is for the purpose of furnishing a ready supply of fresh air to 

 the young developing chick. The air space lies between 

 the outer and inner membranes. 



The white of the egg consists of three important parts : 

 the outer, thicker albumen ; the inner, thinner albumen ; and 

 the chalaza. The albumen supplies in liquid form the food 

 by which the chick grows within the shell. The chalaza 

 consists of white cords of denser albumen that adhere to the 



1 Adapted from J. E. Rice in the Cornell Rural School Leaflet, 

 Vol. I, No. 2. 



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