ARTIFICIAL INCUBATION 73 



will be lost. When the egg is not turned during the latter part of 

 incubation, the embryo does not develop properly, has little chance 

 of hatching or may prove a cripple. 



The turning and moving of the eggs gives exercise to the em- 

 bryo; it is a species of gymnastics for strengthening the chick. 

 The first forty-eight hours and the last forty-eight hours the eggs 

 must not be turned. 



Cooling the Eggs 



Cooling the eggs I consider an important matter in our Ameri- 

 can incubators. The first week, following the hen's example, the 

 eggs require but little cooling beyond the time it takes to turn 

 them. The second week, as soon as the eggs are turned, replace 

 them in the machine and leave the door open for five minutes ; after 

 this increase the time, a minute or two each day, till at the end the 

 eggs are being aired or cooled fifteen or twenty minutes. 



Cooling the eggs helps to make the shell brittle, so that the chick 

 at the proper time can break its way out. Cooling the eggs con- 

 tracts the shell and heating it up again expands it and this con- 

 traction and expansion gives the shell its proper brittleness. As 

 the eggs warm up again, an almost imperceptible moisture comes 

 over them, which takes the place of the perspiration of the hen, and 

 obviates the necessity of sprinkling or dampening the eggs. So in 

 our incubators it is necessary to cool the eggs. If this has been 

 done properly the chicks will be strong and vigorous and few will 

 die in the shell. 



Testing the Eggs 



All sterile eggs and dead germs should be tested out. Egg 

 testers are sold with all incubators and very little practice will en- 

 able even a beginner to detect the sterile eggs and dead germs. 

 Infertile eggs will be of a clear, uniform color throughout, except 

 a slight darkening where the yolk lies. In the fertile eggs will be 

 seen a small dark spot, and in a white egg the blood vessels can be 

 seen branching out from it. Eggs should be tested about the sev- 

 enth day. A second test for removing the dead germs should be 

 made on the fifteenth day, they being easily detected at that time. 

 The chicks in fertile eggs will be seen to fill the shell nearly, except 

 a small space at the small end, and the air space at the large end. 

 All eggs containing dead germs should be removed from the ma- 

 chine and buried. On the eighteenth day the chicks fill the entire 

 shell except the air cell, and the egg will be quite opaque, as if 

 nearly full of ink. To become accurate in egg testing requires 

 practice and a brilliant light. 



Operating the Incubator 



Follow exactly the directions given with whatever incubator 

 you may purchase. The makers of the incubators are anxious for 

 you to succeed and have good hatches ; it is to their interest for 

 you to be successful. They have spent time and money in per- 

 fecting and understand how to manage their own machines better 

 than anyone else. 



