THE EARLY DEVELOPMENT OF THE CHICK 235 



ov 



OS 



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; m, mesovarium ; 01-04, ovarian ova in various stages of 

 growth; O\, 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); on, 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. 



