THE MAMMOTH INCTXBATOB AND BROODER 437 



long is bent in X squares; then cut out Z J-^-inch from the 

 top end and 3-2 by IJ-^ inch and punch holes at S for wire. 



Overheating. — A great danger in artificial incubation is 

 overheating the eggs, which is impossible to happen with the 

 hen. Overheating is more serious than the same degree of 

 underheating. Eggs raised to a temperature of 105° F., and 

 held at that temperature for any length of time, is dangerous, 

 and the embryo may die when the temperature reaches 107° F. 

 The proper hatching temperature is 103° F. The temperature 

 may be allowed to fall to 99° F. for considerable time without 

 apparently destroying the embryo. This delays the hatching 

 a few hours. 



There are not so many eggs chilled or broken in incubator 

 hatching as hatching by the hen. 



An incubator is desirable on the farm where 200 or more 

 chicks are to be raised. Hens are rather uncertain; many are 

 poor sitters, some desert the nests, and a late spring means 

 late sitting, making late hatching inevitable and undesirable. 



Heavy breeds should be hatched in February, or March at 

 the latest, and the light breeds the first week in April. Chicks 

 hatched too late suffer from the heat and do not mature early, 

 and without development there is no proper weight, and weight 

 is needed when making our selection for breeders and layers for 

 the fall and winter and spring work. 



The hatching powers of the incubator are probably not 

 quite so great as those of the hen. 



All incubators before being used should be thoroughly 

 disinfected by scrubbing with a 1 : 500 solution of formaldehyd 

 solution, and both egg and nursery trays should be disinfected 

 in a like manner between each sitting. 



