TIME REQUIRED FOR DEVELOPMENT 399 



and becomes watery, hence it fails to support the yolk, which 

 then gravitates to the membranous lining of the shell and adheres 

 to it. 



Fertility. — All normal eggs contain a life germ, but all life 

 germs are not fertile, and there is no way to determine the fer- 

 tility of the embryo before incubation, except by breaking the 

 shell and examining the contents very closely, and even this is 

 not infallible. The fertile germ has a ring or film surrounding 

 it, which is clear, and in the center may be seen little white dots — 

 rudimentary cells. The sterile germ has a whitish appearance 

 and does not possess the outer ring or the dots. After 24 hours' 

 incubation life is perceptible if the egg is opened. 



Shape and Color of Shells. — Notwithstanding many claims 

 to the contrary, the shape of an egg has nothing whatever to 

 do with its sex. We have shown that the shape of an egg is 

 governed almost entirely by the shape of the oviduct, which is 

 peculiar to every individual and practically constant. The 

 same individuality applies to the color of an egg, which also re- 

 mains more or less constant, except that as the laying season ad- 

 vances the color gradually fades to a lighter shade. The reason 

 for this is plain : the glands which secrete the color pigment are 

 more heavily drawn upon, consequently the supply is somewhat 

 weakened. 



Time for Development.— Just how much time is required for 

 the development of an egg is not definitely known. The forma- 

 tion of the yolk is the longest period, and probably requires three 

 weeks before it is ready to leave the ovisac. The second process, 

 that of accumulating the albumen and forming the shell, is com- 

 paratively short, and requires about eighteen hours. It fre- 

 quently happens that two eggs are under completion in the ovi- 

 duct at the same time. 



Like all secretory organs, these reproductive tissues, glands, 

 and so on, are shrunken and very much contracted when not in 

 use, and enlarge to many times their former size when stimulated 

 to a point of productivity. It is this stimulation — the time re- 

 quired to overcome the inert condition — ^which is of vital im- 

 portance to the poultryman's pocket-book. 



