86 PRACTICAL POULTRY PRODUCTION 



the machine below the egg tray, sprinkling or soaking the 

 floor of the incubator room, or placing a pail of water under 

 the lamp. There is considerably less danger of getting 

 too much moisture in the incubator by the latter methods 

 than by putting moisture directly into the egg chamber. 

 When moisture is added to a non-moisture machine it 

 should be removed before the chicks hatch. When an 

 incubator is run in the room of a dwelhng house, it is 

 frequently necessary to add moisture even to a non- 

 moisture machine. Such machines run in a cellar in the 

 same building might not need additional moisture. The 

 presence of moisture on the glass 

 in the door of the incubator during 

 hatching time is the best indica- 

 tion of correct moisture conditions 

 during incubation. 



The increased size of the air 

 D/<>^n,ms/,om^/f,emr Cell during incubation is caused by 

 ce//onf/K7"i/^'fancy/9c/qy the evaporation of the water in 



of /r?cutiar/or?. mi • n i . 



the egg. The air cell durmg mcu- 

 '^"'^'^ ■ bation varies in size with the size 



of the egg, while the shape of the air cell varies greatly 

 in different eggs. 



Testing the eggs. An egg whether fertile or not has 

 a grayish spot on the surface of the yolk known as the germ 

 spot, or blastoderm. (See Figure 65). When a fertile egg 

 is placed under a hen or in an incubator, the develop- 

 ment of this germ begins. 



White-shelled eggs can be tested on the 4th or 5th day, 

 while the germ development in brown-shelled eggs often 

 can not be seen plainly until the 7th day. Eggs with dead 

 germs quickly decay and give off a bad odor, if allowed to 

 remain in the incubator or in the nest. Infertile eggs make 

 excellent feed for young chicks and should be used for 



