TIME REQUIRED FOR INCUBATION 321 



Time Required for Incubation. , . 



Under normal conditions of temper- x. I ^s x. ^s 



ature and other factors, it will take ^Js^ 



the average hen's egg twenty-one ,. ^ 

 days to complete the process of in- 

 cubation, beginning from the time 

 the egg is subjected to 103 degrees, 

 until the chick is entirely out of the 

 shell. Under artificial conditions, 

 there are causes which may vary the 

 hatching time twenty-four hours "v^lQx 

 either way from the normal. In arti- 

 ficial incubation, the variation in vO I ., \| o^ 

 temperature will materially decrease ^**^ 6 ^^\^ 

 or lengthen the hatching period. A I o 

 high temperature continued for a ^Xlx^ * 

 number of days will shorten the I 

 period, while a cool temperature ex- v> 5 v | x x x g 

 tending over a considerable time will 

 often materially lengthen the hatch- ^ Lx^ 

 ing period to as many as twenty- 

 three days. It is an interesting fact vO I o^ 

 that a variation of two or three ^^J^^ 10 

 degrees from the normal temperature I 

 either way, providing the average VN X|X X n 

 temperature is normal, does not no- I 

 ticeably affect the hatch in any way. >S Q N J X 2 X 12 



Varying amounts of moisture in 

 the incubator also materially affect vO ., vO Ox 



the time of hatching. A high humid- 13 



ity during the last week, and espe- I o o I o 



cially during the nineteenth and ^sL/ 14 ^vj^^ 

 twentieth days, will postpone the 

 hatch as much as from twelve to ]5 



twenty-four hours, but will usually 

 result in a quick, uniform, high per- 

 centage hatch. When managing the 



incubator, long periods Of COOling FIG. 152. Manner of toe punching 



will increase the hatching period. f r baby chi< ; kSl Rowing sixteen com. 



bmations, making it possible to identify 

 Under natural methods, the eggS sixteen different matinga. 



will hatch on the twenty-first day. 

 21 



