Plate II. 

 ( Oogenesis. ) 



Figs. 62-66 were magnified with Zeiss, homog. apoch. immers. 

 -Jg- X 12 compens. oc; the remaining figures, with exception of loi- 

 105, being drawn under Zeiss y^g- obj. x 4 oc. 



Fig. 62- Cross section of metaphase of early generation of oogo- 

 nium showing V-shaped chromosomes. 



Fig. 63. Early generation of oogonium in metaphase in longitu- 

 dinal section. 



Fig. 64. Telophase of the same. 



Fig. 65. Last generation of oogonium in metaphase showing 

 chromosomes as rods. 



Fig. 66. Last generation telophase showing synapsis ; also synap- 

 tic knobs at apices of V's in lower cell. 



Figs. 67-70. Early oocytes, showing polarity of chromosomes and 

 synaptic knobs at apices. 



Figs. 71-72. Early oocytes with chromosomes increased in size. 



Figs. 73-74. First traces of longitudinal split in young oocytes. 



Fig. 75. Oocyte with nearly all the chromosomes longitudinally 

 split. 



Figs. 76-78. Oocytes with chromosomes opening out into longi- 

 tudinally split parallel threads. 



Figs. 79-81. Later oocytes showing the parallel threads separat- 

 ing along their course but often remaining united at one of their ends. 



Figs. 82-83. Two successive sections of the same nucleus. Show- 

 ing the chromosomes at the height of the growth period. 



Fig. 84. Oocyte with chromosomes concentrating into the rings 

 and double rods of the first maturation division. 



Figs. 85-87. Early prophases of 1° maturation division showing 

 chromosomes much more concentrated. 



Figs. 88-90. Late prophase and early metaphase of 1° matura- 

 tion division showing the rings, longitudinally split rods, crosses and 

 true tetrads. 



(62) 



