352 



BEGINNINGS IN ANIMAL HUSBANDRY 



The need of moisture during incubation is commonly 

 recognized. The egg contains from 60 to 65 per cent water 

 and during incubation some of this is lost. In experiments 

 it has been shown that eggs lose from 11 to 17 per cent of 

 their original weight by evaporation. Professor Atwood, 

 of the West Virginia experiment station, has estimated that 

 100 fertile eggs will lose about 8J4 ounces of moisture during 

 the first five days, about 12 ounces during the following seven 

 days, and slightly more during the next seven days. Thus 

 it can be seen that moisture must be provided to some extent 

 during incubation. 



The .need of ventilation during incubation is also well 

 understood. The movement of air about the eggs must be 

 somewhat free, the air being neither too dry or too moist. 

 The hen shifts her position from time to time, and so brings 



fresh air in contact with the eggs 

 and her body. In artificial incu- 

 bation, proper ventilation is so 

 provided that the pure air and 

 right moisture conditions go to- 

 gether. 



The incubator is a box-like 

 device containing a space in which 

 eggs may be incubated by means 

 of artificial heat. The hatching 

 of e ^ s b y artificial incubation 

 ture ' hi State has been in operation for thou- 

 sands of years, especially in Egypt 

 and China. There are various designs of incubators made, 

 ranging in size from those to contain but a few eggs, up to 

 those with a capacity for thousands. Incubators in use 

 at the present time are heated by hot air from a kerosene 

 lamp, or by a hot water system. The hot air type is the one 



u2ive g r e s it f y Agric 



