INCUBATION 411 



embryo has started to develop and has died, the embryo will 

 be observed, but there will be no radiating blood-vessels. 

 With very little experience one can tell an egg that has begun 

 to form an embryo or chick. You wiU ol),sc'rve the so-called 

 blood-ring. All eggs not fertile may be removed from the 

 hen or incubator and are fit for human food, or they can be 

 saved and cooked and fed the baby chicks for the first three 

 or four days. (See chapter on Feeding.) 



Fio. 146. — The air-cells of an egg at different stages of chick development: 

 a, Size of air-cell in the fresh egg; 7, size of air-cell after seven days' incuba- 

 tion; 14, size of air-cell after fourteen days' incubation; 19, size of air-cell 

 after nineteen days' incubation. 



A second candling should be made at the end of 14 days, 

 at which time all eggs containing dead germs should be removed. 

 In the recandling the air cells of eggs with dead germs will 

 be cloudy, while those with live germs will be clear. 



A piece of black cardboard may be used as an egg tester. 

 Cut an oval hole in the center and in a dark room hold the 

 egg to the hole and the apparatus between you and the light. 



Supply each hen with fifteen eggs that have shown evidence 

 of containing live embryos, and if you have one hen without 

 eggs give her fifteen fresh eggs . A good way to care for the hen 



