A HARD-BOILED EGG 13 



Draw the egg as you see it in the saucer. Label the parts. 



Put a drop of the yolk on a slide, add a little water, and 

 examine it with the microscope. What is the appearance 

 of the yolk granules? Are they uniform in size? 



Draw some of the yolk. 



b. A Hard-boiled Egg 



Break the shell of a hard-boiled egg and remove with- 

 out breaking the white. Observe, again, the air-chamber 

 and the character of the shell and the shell-membrane. 

 Try to peel off the white in thin layers. It will be seen 

 that the white is arranged in the form of a spiral. What 

 is the direction of the spiral? Where is the apex of the 

 spiral? Peel off all the white. Usually the vitelline 

 membrane is also taken off from the yolk with the white. 

 Observe the vitelline membrane. 



On one part of the yolk there is a disc that is lighter in 

 color than the remainder of the surface of the yolk. 

 This disc is called the "nucleus of Pander." With a 

 sharp knife or razor cut through the "nucleus of Pander " 

 in such a way as to divide the yolk into two hemispheres. 

 If the egg is fresh, it will be seen that the "nucleus of 

 Pander" is connected by means of a narrow neck to a 

 central portion of the egg composed of similar material. 

 This is lighter in color and is more liquid than the other 

 yolk. It is composed of the so-called white-yolk. The 

 darker yolk material is called yellow yolk. It will be 

 noticed that there are alternate layers of white yolk 

 and yellow yolk. How many layers are there? Which 



