up and down. This is a strong, fertile egg, and 

 should hatch under a good hen or in a good incu- 

 bator. In a well fertilized egg the blood vessels 

 should show plainly, but the germ is not always 

 seen as plainly, varying with the color and thick- 

 ness of the shell and the power of the tester used. 

 C, shows about the average air bulb in an egg on 



A STALE EGG. 



As shown on fifth or sixth day : clouded, doubtful ; many such 

 should be broken. 



the fifth or sixth day of incubation, though it may 

 vary according to the freshness of the egg, and 

 some eggs have larger air bulbs than others. 



Fig. 2, shows a weak or imperfectly fertilized 

 egg as seen in the tester on the fifth or sixth day. 

 H, is an oblong or circular blood vessel which has 

 43 



