CHAPTER IV 

 NATURAL AND ARTIFICIAL INCUBATION 



The incubation of eggs by artificial methods has made 

 great progress within recent years. There is no question 

 that artificial incubation as carried on with our present 

 day incubators is thoroughly practical and possesses many 

 advantages over hatching by natural means. A thorough 

 understanding of the fundamentals of incubation and incu- 

 bator operation as given herein, coupled with good manage- 

 ment, will assist materially in securing satisfactory hatches. 



PRELIMINARY CONSIDERATIONS 



THE EGG 



Before considering the subject of incubation a study of 

 the construction of the egg will assist in understanding 

 the suggestions as given for handling eggs that are to be 

 incubated. The shell of the egg is porous, and consists 

 of an outer and an inner layer, under which are two mem- 

 branes. These membranes are separated at the large end 

 of the egg and form the air cell. The air cell in a fresh 

 egg is about as large as a ten cent piece and increases in 

 size as the water in the egg evaporates. (See Figure 84.) 

 Surrounding the yolk is the white of the egg, or albumen. 



/9/Ai,yn/=n /// J /^"-y^-j—y ^^^g— Inner n7enti>rane 



/9/r ce/f mhn<>^^^^^Apr><^>J^^<'f'''^'^ 



* IBrafJ i T I r 1 I ■ ~ < I I I iJ^/ H/.iill 



Figure 65. — Cross-section of ao egg showing its structure and aeveral parts. 



67 



