172 PROFITABLE POULTRY PRODUCTION 



small, dark center (the heart) from which blood 

 vessels radiate in every direction. The infertile 

 or sterile eggs will be perfectly clear when held 

 up to the light. Eggs that contain dead germs can 

 be distinguished by a small, dark center, though 

 sometimes this is lacking, surrounded by an irregu- 

 lar circle and the absence of blood vessels. 



When the eggs are tested on the fifteenth day 

 those that contain live chicks will appear, when 

 held to the light, to be filled with a dark mass, 

 which in reality is the developing embryo. The 

 infertile eggs should be saved and used in feeding 

 the young chicks for the first few days ; they may 

 also be used for baking purposes, as a slight 

 evaporation is the only change that has resulted 

 from incubation. The eggs should not be turned 

 ,or cooled after the eighteenth day. Close the 

 (machine and do not disturb it, except to fill and 

 itrim the lamp, until the hatch is complete. While 

 Ithe eggs are hatching, the temperature of the 

 imachine may go as high as 105 or even 107 de- 

 grees ; this is caused by the animal heat given off 

 by the chicks and no attempt should be made to 

 lower the temperature if the machine has been run- 

 ning properly just previous to hatching. 



Before resetting, the machine should be cleaned 

 and disinfected thoroughly, a new wick put in the 

 lamp, and operated for a day or more in order to 

 adjust the regulator properly. 



CARE OF THE INCUBATOR 



Many incubators are short-lived. The owners 

 complain of unsatisfactory results after the first 

 season or two, but the trouble is more often due to 



