CHAPTER IV. 

 What is an Egg ? 



The egg is the first stage in the reproduction of birds. Its function 

 primarily is to produce offspring, secondarily to furnish food for the 

 embryo and for man. The hen therefore fulfills dual purposes which in 

 a measure are antagonistic in their requirements. The first demand of 

 nature is that the hen shall produce eggs that possess all the qualities ot 

 life and nutrition necessary to produce strong chickens; the second, that 

 she shall furnish eggs good to eat and lots of them. In order to satisfy 

 the commercial requirements of man the hen often is compelled to sacri- 

 fice the higher demands of nature. It becomes a vital question therefore 

 for every poultryman to decide to v^^hat extent he can force heavy lay- 

 ing w^ithout sacrificing the fertility of the eggs or the vitality of the 

 chickens. It is well, then, that we inquire what an egg is and how it is 

 formed. 



HOW THE EGG IS MADE.— The first stage in the development of 

 the egg is the formation of the "yolk." The "ovary" or "egg cluster," 

 which forms a part of the muscular tissue on the left side of the 

 spine, contains many yolks in various stages of development, depending 

 upon the condition of the hen, from the full-sized ripe yolk ready to bt 

 detached, to the microscopic cells so small that they cannot be discerned 

 by the naked eye. Within this ovarian tissue is the power to develop 

 countless other yolks not yet apparent. The number of these yolks or 

 "ova," which may be developed, is not a fixed quantity, certainly not 

 exactly 600, as is frequently stated. The number of eggs which a hen 

 will lay depends upon the inherited tendency of each hen to reproduce, and 

 upon her vigor and vitality to withstand the heavy drain upon her system. 

 The ovary of certain hens is absolutely sterile. Others have the power to 

 produce a few eggs in short litters, while some have an ovary so strong 

 and reproductive that they lay almost without interruption, and continue 

 to do so for years. The egg-laying power is a matter of inheritance. It 

 is a question of selection and breeding, and of stimulating the ovaries 

 to activity by proper feeding. 



Fig. 1, next page, shows ovary of a hen ; 2 is the yolk held within 

 the ovisac or follicle (5). When the yolk is fully ripe it bursts from the 

 follicle and drops into the neck of the oviduct (7). Here we see a wise 

 provision of nature. In order to prevent rupture of blood vessels where 

 the follicle opens, there is a suture mark around the entire surface, where 

 the blood vessels meet but do not cross (4). If for any reason the folli- 



