THE EARLY DEVELOPMENT OF THE CHICK 235 



2 



ov 



f 0, 



4 



OS 



da 



cl 



FIG. 86. The reproductive system of the fowl. After Duval (Coste). The 

 figure shows two eggs in the oviduct, whereas normally only one egg is in the 

 oviduct at a time, b, Blastoderm; c cicatrix; cl, cloaca; da, dense layer of 

 albumen;/, empty egg follicle from which the ovum has escaped; g, glandular por- 

 tion of oviduct; i, isthmus; ra, mesovarium ; 01-04, ovarian ova in various stages of 

 growth; Oi, ovum in upper end of oviduct; Oz, ovum in middle portion of ovi- 

 duct (the oviduct has been cut open to show the structure of this ovum) ; os, os- 

 tium or infundibulum; ov, ovary containing ova in various stages of growth; 

 r, rectum; u, uterus; v, vitellus; w, ventral body wall, opened and reflected. 



