88 INCUBATION 



The records of artificial incubation are derived from 

 experiments with different makes of incubators. 



The hatch from hens ranged as high as 83.3% and as 

 low as 50%, and that of the incubator from 77.1% to 

 32.5%. 



Selection of Eggs for Incubation. Eggs for hatching 

 in an incubator should all be of one kind, size, and 

 color; for only when eggs of such character are incu- 

 bated together can uniform hatching be secured. 



Eggs from Leghorns and Brahmas do not hatch well 

 if both are together in the same incubator, for the 

 eggs of the Leghorns usually hatch during the twentieth 

 day, and the hatching of the Brahma eggs may be 

 delayed to the end of the twenty-first day. If eggs 

 from Leghorns, Plymouth Rocks, Wyandottes, and 

 Brahmas are all together in the one incubator the hatch 

 is irregular. Eggs but 1 da. old hatch a day sooner 

 than eggs that are 2 wk. old. Leghorn eggs placed in 

 an incubator on the day they are laid may hatch in 

 480 hr. ; eggs of Asiatic fowls placed in the same 

 incubator when 2 wk. old may not hatch for 516 hr., a 

 difference in time that makes poor results inevitable 

 if the eggs of both breeds are incubated together. 

 The eggs of ducks and of chickens cannot be suc- 

 cessfully hatched together in the same incubator, nor 

 do the eggs of any two or more kinds of fowls hatch 

 well if placed together in the same incubator or under 

 the same hen. 



If the eggs are of uniform size, the temperatures of 

 all are equal or nearly so; if large and small eggs 

 are in the same machine the temperature may not be 

 the same in all. 



Eggs with white shells hatch in fewer hours than do 

 the dark-shelled eggs, for white shells are thinner and 

 transmit heat more freely to the germ within. Under 

 the same conditions, eggs with white shells will have 

 larger air cells than those with heavier shells. 



Only smooth and well-formed eggs should be used; 

 eggs with uneven surface, bad form, rough shells, or 



