OVARY AND OVISAC 391 



is correct we need only concern ourselves with about 700. The 

 number is not a fixed quantity, and those which will be developed 

 is still less certain. The prolific power of a hen is largely an in- 

 herited tendency, the result of careful selection and breeding, made 

 potent by careful handling and feeding. Both elements are abso- 

 lutely essential, as we have shown in preceding chapters. 



The ovary or egg cell cluster which contains the latent eggs is a 

 muscular tissue on the left side of the spine. In it, in various 

 stages of development, from the full-sized yolk, ready to be de- 

 tached, to the cells which are so small as to be invisible without 

 the aid of a microscope, are the yolks or ova. When a yolk is 

 fully matured and ripe, it bursts from the tough membrane of the 

 ovisac and enters the neck of the oviduct, a convoluted, muscular 

 tube some twenty inches long, wherein the albumen or white is 

 deposited, and later the shell is formed. See Frontispiece. 



The ovisac is lined with blood-vessels, yet provision is made in 

 the healthy, normal hen that when the yolk ruptures this mem- 

 brane the blood-vessels are parted to one side and not broken. 

 It occasionally happens, however, either through an injury to the 

 fowl, fright or weakness due to a debilitated condition, that one 

 of the blood-vessels may become slightly ruptured, whereupon a 

 blood clot will escape with the yolk and later be incorporated with 

 the albumen. This accounts for spots of blood found in strictly 

 fresh eggs, and which have led many consumers to believe they 

 have purchased partly incubated eggs. 



Double Yolk Eggs. — It sometimes happens that two yolks 

 mature and burst through the ovisac at the same time; in this 

 event they are likely to become encased with albumen together, 

 and subsequently surrounded by the same shell, producing a 

 double-yolked egg. Occasionally a mass of albumen will be de- 

 posited without yolk or shell, or it may be laid with a perfectly 

 formed shell but without a yolk; or a yolk will be laid without 

 albumen or shell, and in rare cases a perfectly formed egg has 

 been found within an outer egg shell. These freak conditions 

 are brought about by improper care and feeding, but more 

 especially by fright, neglect or injury. 



