CHAPTER XIX 

 TESTING EGGS DURING INCUBATION 



Inasmuch as all eggs are not fertile, and because all fertile 

 eggs do not contain embryos that develop properly, it has be- 

 come a rule to test the eggs during the period of incubation, first 

 for fertility, and later for the strength of the embryo. It will be 

 readily understood why this information is desirable: In the 

 first place, by removing the infertile or clear eggs, which may be 

 used for culinary purposes or hard boiled and fed to little chicks, 

 additional room will be created on the egg trays, which means 

 greater ease and convenience in the operation of the incubator. 

 Then again, if the dead germs are removed the egg chamber is 

 more easily kept free from bad odors, and this is a worthy factor. 



Since there is no way to determine if an egg is fertile before 

 placing it in the incubator, we must endeavor to gain this in- 

 formation -v^hile the eggs are being hatched. Claims have been 

 made that fertility can be told before incubation. These theories 

 have no basis in scientific fact. They are usually offered for 

 some pecuniary gain, and should be discarded. 



Construction of an Egg. — The yolk of a fresh egg floats in a 

 dense mass of albumen, popularly known as the white, which is 

 in the form of layers. These layers are particularly noticeable 

 in the hard-boiled egg. Attached to the yolk are two cords, 

 called the chalaza. The ofiEtce of these cords is to suspend the 

 yolk in the white and keep it from injury, and to keep the life 

 germ which is attached to the vitelline membrane of the yolk 

 in a certain position where it will receive the fullest effect of heat 

 during incubation. See chapter on the development of an egg. 



Experiment and you will soon see that no matter how you twist 

 or turn an egg, the yolk will always return to a definite position. 



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