EGG AND FEMALE ORGANS OF GENERATION. 



551 



Fig. 180. 



in abundant, projecting, leaf-like villosities, exudes a fluid very rich 

 in calcareous salts. The most external of the three membranes 

 just described is permeated by this fluid, and very soon the calcare- 

 ous matter begins to crystallize in 

 the interstices of its fibres. This 

 deposit of calcareous matter goes 

 on, growing constantly thicker and 

 more condensed, until the entire 

 external membrane is converted into 

 a white, opaque, brittle, calcareous 

 shell, which incloses the remaining 

 portions and protects them from ex- 

 ternal injury. The egg is then driven 

 outward by the contraction of the 

 muscular coat through a narrow por- 

 tion of the oviduct (h), and, gradually 

 dilating the passages by its conical 

 extremity, is finally discharged from 

 the external orifice. 



The egg of the fowl, after it has 

 been discharged from the body, con- 

 sists, accordingly, of various parts; 

 some of which, as the yolk and the 

 vitelline membrane, entered into its 

 original formation, while the remain- 

 der have been deposited round it dur- 

 ing its passage through the oviduct. 

 On examining such an egg (Fig. 181), 

 we find externally the calcareous 

 shell (h), while immediately beneath 

 it are situated the middle and internal 

 fibrous shell-membranes (e,f). 



Soon after the expulsion of the egg 

 there is a partial evaporation of its 

 watery ingredients, which are replaced 

 by air penetrating through the pores 



F -MALE 'GENERATIVE ORGANS OF FOWL. ft. Ovary. &. Graafian follicle, from which the 

 egg has just been discharged, c. Yolk, entering upper extremity of oviduct. d,e. Second division 

 of oviduct, in which chalaziferous membran*, chalazse, and albumen are formed. /. Third portion, 

 in which the fibrous shell membranes are produced, g. Fourth portion laid open, showing egg 

 comp'etely formed, with calcareous shell, h. Narrow canal through which the egg is discharged. 



