an undesirable effect upon the egg next to it, either 

 under the hen or in the incubator. 



An unfertile egg one which has not been im- 

 pregnated, and in which life will never start or 

 develop is clear when shown at the tester. This 

 egg under the powerful lens of a first-class tester, 

 will show the yelk, which must not be mistaken 

 for a doubtful or fertile egg. 



Use only the very best egg- tester. 



HOW THE CHICKS DEVELOP. 



Fig. 7 shows the heart and minute arteries and 

 veins in a circle on the yelk which is enclosed in a 

 thin sac. They are plainly seen by the naked eye 

 when a strong fertile egg is carefully broken into a 



