PRAIRIE FARMER'S POULTRY BOOK 



Egg types, showing variation in size, also illustrating how the eggs may decrease in size 

 from the first egg of the clutch to the last 



a long period and that each germ cell is fertilized as it is dis- 

 charged into the infundibulum. It is not unlikely that the 

 spermatozoa gain access to the ovary and that all the eggs of 

 the clutch are fertilized very soon after copulation. 



How long after a male bird is introduced into a pen before 

 the eggs will become fertile? The sperm cells are provided 

 with slender tail-like filaments, or flagellae, with which they 

 propel themselves by a whip-like motion, and it is quite 

 probable that some of them reach the mouth of the oviduct 

 within 24 hours. Some eggs, therefore, may be fertile within 

 two or three days. Certainly, in five to 10 days all eggs should 

 be fertile if conditions are normal. 



Detecting Infertility and Sex of Eggs 



To detect whether an egg is fertile or not before incubation 

 is a problem vital to the poultry industry. After a few days of 

 required temperature fertile eggs show plainly the developing 

 embryo, whereas the infertile egg gives no such evidence. 

 After the infertile egg has been subjected to heat in this 

 manner for several days it loses its freshness and is subject to 

 decay much more than the fresh egg. It is, therefore, unfit for 

 market but may be used for cooking purposes in the home. 



As the embryonic cell in a fertile egg differs somewhat in 

 structure from an infertile cell, being enveloped with a distinct 

 ring, it has been thought that fertility and non-fertility could 

 be detected by a powerful" lens, but the structural characters 

 are so delicate and the shell and membranes offer such inter- 

 ference to light that this method will probably prove im- 

 practical. 



It is not impossible that an instrument will yet be devised 

 that will determine not only fertility but the sex of the embryo. 



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