CHAPTER V. 

 Hatching the Egg. 



WHAT IS INCUBATION?— A barnyard hen of the larger breeds 

 will, if left to herself with enough food, "steal her nest." She finds some 

 secluded place, makes a shallow hole and lays a clutch of eggs in it. She 

 then sits on the eggs, leaving them at intervals for water and food and 

 to dust herself, until they are hatched. It is sometimes asked why such 

 a hen, operating in this crude way, will hatch more and stronger chicks 

 than an incubator, or than most hens when put on selected eggs in a com- 

 fortable nest. The chicks from the stolen nest are generally uniform be- 

 cause they are likely to be all from one hen; thus they are sure to be 

 much alike, and more likely to be fertile than when picked from a flock. 

 They are strong because the hen works for her food, roaming about the 

 farm picking up a variety, and exercising so as not to be too fat or dumpy. 

 Left to herself, too, the hen lays eggs in her stolen nest just when they are 

 most likely to be suitable for hatching. Thus she sets an example in feed- 

 ing, selection and breeding. In trying to breed improved stock man 

 attempts to imitate the barnyard hen, and at the same time increase the 

 number of her eggs and make sure of her mating. In the same way when 

 we build an incubator we try to imitate the hen by putting the eggs in 

 a box in a chamber where they may be surrounded by the conditions of 

 heat and moisture which the hen puts around her eggs in the nest. 



A broody hen is fat. The organ of incubation is developed. This organ 

 is a network of veins on the lower part of the hen's body. At the time 

 of hatching, that is, when the hen becomes "broody," these veins enlarge 

 and carry more blood, so that a warmer surface is presented to the eggs than 

 would be the case if the hen were not broody. The hen's feathers permit 

 a slight circulation of air to the eggs, and some little moisture comes from 

 her body. The hen leaves her nest at times, or stands up and shakes 

 herself, thus cooling the eggs. She also moves the eggs about from time 

 to time. It is a question whether the hen does this because she knows it 

 is necessarj', or because she tries to arrange the eggs so as to make the 

 nest most comfortable. In artificial incubation it has been found best to 

 turn the eggs frequently, the chief reason given for doing so being that if 

 the eggs are not turned the germs may dry fast to the shells early in 

 the hatch. 



In artificial incubation we attempt to surround the eggs with temper- 

 ature and moisture such as the hen gives them from her body. Under 

 the influence of a steady, gentle heat the life in the egg develops rapidly 

 and in perfect order. An incubator cannot think, and the best of man's 



