TURNING THE EGGS 253 



meant that each egg should be turned over an exact i8o degrees, 

 simply that the position of the egg should be sufficiently altered, 

 so that the germ will not gravitate and adhere to the mem- 

 branous lining of the shell. Some operators turn their eggs 

 three or four times a day. It has never been satisfactorily 

 demonstrated that these extra turnings insure better hatches, 



(Courtesy Buckeye Incubator Company) 



Fig. i6i. — Phantom view of mammoth incubator in which the egg trays 

 are arranged in tiers to save space. An even distribution of heat is main- 

 tained by means of electric fans inverted in the top of the machine. 



though it is reasonable to suppose that they do. The hen is 

 known to turn her eggs eight or ten times a day ; but in her case 

 this is necessary to overcome the variation in temperature in the 

 different parts of the nest. 



Best results are obtained when the eggs are turned by rolling 

 them with the hands. The trays of the larger sized machines 



