LABORATORY MANUAL OF AGRICULTURE 



side of the yolk toward either end. These cords serve to 

 keep the yolk suspended properly within the albumen. 



The yolk of the egg consists of three parts : the germ spot, 

 light yolk, and dark yolk. The germ spot appears as a 

 light-colored spot usually found on the upper surface of the 

 yolk. It is from this germ that the young chick develops. 



There is a tendency 

 for the yolk to float 

 at the surface of the 

 egg. It is therefore 

 necessary to turn fre- 

 quently eggs that are 

 to be used for hatching. 

 If the egg is not turned 

 frequently, the yolk 

 will rise until the germ 

 comes in contact with 

 the shell membrane. 

 It will then become 

 dry by evaporation and adhere to the membrane. If the 

 egg is then turned, the germ will be killed. Figure 28 shows 

 a cross section of an egg. 



Equipment. 1. Two eggs, one light and one dark, for 

 each member of the class. 



2. Two saucers for each member of the class. 



3. A sauce pan. 



4. Some means of boiling an egg. 1 



5. A knife. 



FIG. 28. Sections of an egg. 1, germ spot; 

 2, light yolk ; 3, dark yolk ; 4, chalaza ; 



5, the inner, thinner white or albumen ; 



6, the outer, thicker white or albumen ; 



7, inner membrane ; 8, air space ; 9, outer 

 membrane ; 10, shell. 



1 If the eggs cannot be boiled at school, have each student bring 

 a boiled egg from home. 



