. The development of the chick; an introduction to embryology . iata of older ova. The third phase of ovogenesis, maturation or formation ofthe polar globules, is transferred to the next chapter, because itis overlapped by the process of fertihzation. It is not definitely THE EGG 31 known if maturation in birds may be completed without fertiliza-tion, but it seems probable that, as in many other animals, thecompletion of maturation is dependent on the stimulus of fertihza-tion. It is, however, essentially a process absolutely distinctfrom fertilization, and in some animals {, echinids) is
. The development of the chick; an introduction to embryology . iata of older ova. The third phase of ovogenesis, maturation or formation ofthe polar globules, is transferred to the next chapter, because itis overlapped by the process of fertihzation. It is not definitely THE EGG 31 known if maturation in birds may be completed without fertiliza-tion, but it seems probable that, as in many other animals, thecompletion of maturation is dependent on the stimulus of fertihza-tion. It is, however, essentially a process absolutely distinctfrom fertilization, and in some animals {, echinids) is com-pleted without fertilization. CHAPTER IITHE DEVELOPMENT PRIOR TO LAYING I. Maturation During the growth period the germinal vesicle has increasedto an enormous size (455 x 72 ju in an ovmn 37 mm. in diameter,Fig. 8). It lies in contact with the vitelline membrane. Themargins of the lenticular nucleus are folded into the interior insuch a way that sections give an effect of rod-shaped bodies spring-ing from the membrane which were doubtfully interpreted as. ^-^
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