CHAPTER II 

 THE DEVELOPMENT PRIOR TO LAYING 



I. MATURATION 



THE phenomena of the maturation and fertilization of the hen's 

 egg are almost entirely unknown. The observations of Holl 

 demonstrate only that the wall of the germinal vesicle tends to 

 disappear when the follicle is nearly ripe. He also doubtfully 

 identified six rod-shaped bodies at the margin of the germinal 

 vesicle as the chromosomes of the maturation spindle (Fig. 8). 



FIG. 8. Section of the germinal vesicle and surrounding parts 

 of an ovarian ovum of the hen measuring 40 x 35 mm. (after 

 Holl). 



Chr., Chromosomes. Gr., Granulosa. G. V., Germinal vesi- 

 cle. Z. r., Zona radiata. 



But we have fortunately a very good account of the maturation 

 and fertilization of the pigeon's egg by E. H. Harper, which fur- 

 nishes the basis of the following description: 



The wall of the germinal vesicle begins to break down in ovarian 

 eggs of about 18.75 mm. diameter, the full size of the egg of the 

 pigeon being about 25 mm. Part of the fluid contents of the 

 germinal vesicle flows out and forms a layer outside the disinte- 



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