268 



COMMERCIAL POULTRY RAISING 



Testing Eggs. — It is customary to test hatching eggs twice, 

 the first time on or about the seventh day, for fertiHty, in which 

 the clear eggs are removed; and the second time at the end of 

 the second week, though some operators, if they make their first 

 test on the seventh day, which is pretty sure to remove most of 

 the dead germs, prefer to make the last test on the evening of the 

 eighteenth day, when the eggs are turned and cooled for the last 



time, and the machine 

 is to be closed until the 

 hatch is completed. 



The shells of white 

 eggs are so translu- 

 cent that they can be 

 tested on the third 

 day, which is a big 

 convenience. The 

 shells of brown are so 

 dense and thick that 

 it is difficult to see the 

 contents with any de- 

 gree of accuracy until 

 the seventh day. 



The process of test- 

 ing eggs is simple 

 enough after a little 

 experience is acquired . 

 It consists mainly in 

 holding the egg between the eye and a strong light, which illu- 

 minates the interior of the egg. In fact, it is precisely the same 

 as candling eggs. See Fig. 169. 



Egg Testers.^There are many types of egg testers on the 

 market, and the manufacturers of incubators usually furnish 

 one with each machine. The simplest device is a tube or chim- 

 ney of tin to fit over an oil lamp, and on one side of the tube there 

 is a small opening, against which the egg is held for an examina- 

 tion. See Fig. 170. Eggs may also be tested by sunlight, using 



Fig. 170. — Simple egg candling outfit — ordinary 

 lamp and cardboard box. 



