Incubation 185^ 



Moisture on the glass door of tlie incubator at pipping time usually in- 

 dicates a good hatch. This moisture is due to the large amoimt evaporated 

 from the chicks. 



Controlling ventilation. — In some cases ventilation is controlled by- 

 slides over the ventilator openings, which are usually in the bottom of 

 the incubator. In using incubators of this type, it is a good practice 

 to restrict ventilation during the first five days of incubation by keeping 

 the slides closed, opening them gradually after the fifth day until the\' ai-e 

 wide open. The temperature of the room must be considered in regulating 

 the ventilators ; and the warmer the weather is, the wider the ventilators 

 may be opened. Some incubators have additional ventilators to be 

 opened only after the chicks are through hatching; these must not be 

 mistaken for the ventilators that are to be used during incubation. Con- 

 stant ventilation is provided in some types of incubators that are not 

 fitted with slides. Such machines should never be tampered with. The 

 necessity of following the manufacturers' directions in regard to venti- 

 lation cannot be too strongly impressed on the mind of the novice. 



HANDLING THE EGGS 



The eggs should not be placed in the incubator until it has been heated 



for several days and properly regulated, and all directions have been 



followed in regard to adjustment of parts, special attention having been 



given to the manufacturers' directions 



concerning ventilators, felts, trays, 



and the like. Eggs of a uniform size, 



shape, and color shotdd be chosen so 



far as possible, and those with very 



porous or otherwise defective shells 



should be eliminated (Fig. 64). A 



few more hours are usuallv required Fig. 6j^.—Eggs for incubation; i, Se- 



, , . . , , ' lected; 2, non-selected 



m hatchmg eggs from the hea\'^' type 



of fowls than are needed for leghorn eggs; therefore it is not advisable 



to set the two kinds of eggs together in an incubator. 



Turning the eggs. — From the time when the eggs become thoroughly 



heated until the chicks issue from the shells, more or less evaporation 



of the egg contents takes place. The yolk being lighter than the albumen, 



unless the position of the egg is changed at frequent intervals, there 



is a tendency for the yolk to gradually rise; and, as the developing germ 



retains its position on the upper side of the yolk, it will in time be forced 



against the inner shell membrane and become dried fast to it, this condition 



resulting in death to the germ. It is said that the sitting hen turns her 



eggs several times during the day and night; but conditions existing 



