ness of the shell and age of the egg when set ; 

 then some eggs are not as full as others. At this 

 stage of incubation (sixteenth day) a live chick 

 darkens the egg, except the air bulb, when seen 

 with the tester, and by watching the line I or J, 

 the chick may often be seen to move. 



Eggs should be tested in a warm room, one tray 

 at a time. 



A LIVE EGG. 

 The air space on the sixteenth day. 



The chick is harder to see after the seventh day, 

 because the egg becomes more clouded by the 

 growing chick. 



NOTE. In regard to G, in Fig. 2, "a partially 

 fertilized germ" means one that from one of sev- 

 45 



