INCUBATION 251 



hot weather) because her eggs are making her uncomfortably warm. 

 Unless it is known that eggs have been chilled beyond recovery, 

 the damage due to chilling can be ascertained only by continuing 

 incubation, and testing after a sufficient time has elapsed to plainly 

 show whether development has stopped. In cold weather, eggs left 

 by a bird for only ten or fifteen minutes may be fatally chilled, 

 while in warm weather a bird may remain off for hours at a time 

 without impairing the hatch. An actual chill probably always does 

 damage, but circumstances or superior hardiness sometimes save 

 the germs in some eggs. Cases have been known of vigorous 

 chicks hatching from eggs in nests where most of the germs were 

 destroyed by a chill. 



When the eggs begin to hatch. The inclination of the mother is 

 to keep the nest until she is ready to leave it with her young. In 

 houses where the sitters are under control, it is well now to keep the 

 nests closed. The advantage of protecting an outside nest is empha- 

 sized at this stage. A nest cover like those shown in Figs. 278 and 

 279 can be completely closed by a board in front of the entrance, 

 and the sitting bird protected from outside interference at the time 

 when it is most dangerous to her brood. If she is in good condition 

 it will be no serious hardship for her to go without food and water 

 for two or three days, while if she leaves the nest, the air may dry 

 the membranes in pipped eggs and there is risk of her crushing 

 in the shells as she returns. On all accounts she should be allowed 

 to remain quiet. Birds that become too restless and crush their 

 eggs should be removed and others substituted, or (if that cannot 

 be done) the eggs should be taken away. 



To avoid losses at this stage some poultrymen who hatch mostly 

 with hens transfer the eggs to incubators at about the eighteenth 

 day, returning the chicks to the hens when dry and ready to begin 

 eating. When this is not practicable, and the mother seems likely 

 to lose many of the young as they hatch, the eggs may be put (in 

 the old-fashioned way) into a flannel-lined box or basket and kept 

 in any safe, warm place until they hatch. The nests should be ex- 

 amined only to observe in a general way how things are progress- 

 ing, and to correct anything going wrong. As a rule, the hen that 

 seems to be doing well should be let alone, the hen that is not doing 

 well relieved of responsibility. When things are going well, all that 



