74 ANATOMY OF THE EGG. 



It is perforated with numerous poreo, 

 through which the air passes during incuba- 

 tion. It is sometimes entirely wanting, 

 which is generally attributed to the fact 

 that the fowl has had no access to lime be- 

 fore laying. The shell, however, is known 

 to be the last part formed, and this with 

 great rapidity, while in the oviduct. It is 

 probable, therefore, that those eggs without 

 a shell result from the ardent desire to lay 

 a desire which does not permit the egg to 

 remain twenty hours, or long enougTi in the 

 oviduct to receive its hard shell. The 

 French poulterers attribute this want of a 

 calcareous covering, or shell, to the exces- 

 sive fatness of the fowl, and recommend to 

 diminish the quantity of food, and give 

 chalk in the water, and pounded bricks 

 mixed with its food. On the inner surface 

 of this hard shell we notice a firm white 

 membrane, termed the skin ; at the large! 

 end this forms a cavity, filled with air, anc 

 which enlarges during incubation. The 

 glair e, or white, is divisible into two por 

 tions, or layers, each surrounded by its pe 



