TIME REQUIRED FOR INCUBATION 



321 



Time Required for Incubation. — 



Under normal conditions of temper- 

 ature and other factors, it will take 

 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 

 either way from the normal. In arti- 

 ficial incubation, the variation in 

 temperature will materially decrease 

 or lengthen the hatching period. A 

 high temperature continued for a 

 number of days will shorten the 

 period, while a cool temperature ex- 

 tending over a considerable time will 

 often materially lengthen the hatch- 

 ing period to as many as twentj^- 

 three days. It is an interesting fact 

 that a variation of two or three 

 degrees from the normal temperature 

 either way, providing the average 

 temperature is normal, does not no- 

 ticeably affect the hatch in any way. 

 Varying amounts of moisture in 

 the incubator also materially affect 

 the time of hatching. A high humid- 

 ity during the last week, and espe- 

 cially during the nineteenth and 

 twentieth days, will postpone the 

 hatch as much as from twelve to 

 twenty-four hours, but will usually 

 result in a quick, uniform, high per- 

 centage hatch. When managing the 

 incubator, long periods of cooling 

 will increase the hatching period. 

 Under natural methods, the eggs 

 will hatch on the twenty-first day. 

 21 



16 



Fig. 152. — Manner of toe punching 

 for baby chicks, showing sixteen com. 

 binations, making it possible to identify 

 sixteen different matings. 



