PLATE 2 



EXPLANATION OF FIGURES 



All figures on this plate are of primary oocytes 



14 Cross-section of oviduct, showing single layer of primary oocytes with 

 peripherally placed nuclei. Rhachis degenerating. (X 550) 



15 Chromatin of prophase nucleus condensed into one peripheral mass, the 

 linin network disappearing, and vacuolation of the cytoplasm begun. Plasmo- 

 some discrete. (X 1700) 



16 Prophase nucleus, with linin network entirely broken down. Plasmo- 

 some degenerating. (X 3200) 



17 Prophase nucleus, with slight evidences of vacuoles in the chromatin 

 mass. Linin network and plasmosome degenerating. (X 3200) 



18 Prophase nucleus, showing resolution of discrete chromosomes from 

 chromatin mass. Plasmosome granules at the left. (X 3200) 



19 Prophase nucleus, with fully formed monad chromosomes and a discrete 

 plasmosome. (X 3200) 



20 Prophase chromosomes with a Querkerbe and increased number of vacu- 

 oles in the cytoplasm as the cell becomes more nearly spherical. (X 1700) 



21 Slightly older than that of figure 20. (X 3200) 



22 Prophase nucleus, showing beginning of longitudinal split in the thirty- 

 six dyad-like chromosomes. (X 3200) 



23 Prophase nucleus, showing union of thirty-six tetrads by parasyndesis to 

 form eighteen di-tetrads. (X 3200) 



24 Prophase nucleus, showing degeneration of plasmosome and the extru- 

 sion of some of its elements into the cytoplasm. (X 3200) 



25 Nucleus, of same age as the one shown in figure 24, with the plasmosome 

 degenerating and disappearing in situ. (X 3200) 



26 Beginning of the first maturation spindle and the arrangement of the chro- 

 mosomes into an equatorial plate. Nuclear membrane breaking down at poles 

 of spindle. First appearance of centrosomes. (X 1700) 



588 



