PLATE 6 



EXPLANATION OP FIGURES 



Hybocodon prolifer 



49 Portion of a longitudinal section through stomach wall of developing 

 secondary medusa, of a stage about like that of figure 48, ectoderm to the left. 

 X 615. 



50 Part of a transverse section of stomach of developing secondary medusa, 

 considerably older than figure 49, ectoderm uppermost in figure. X 615. 



51 Oocytes of a mature medusa, just ready to begin growth. Shows the 

 character of cytoplasm, nucleolus, and nucleus; extra-nuclear chromatin in 

 cytoplasm. X 1150. 



52 An oocyte from same ovary as figure 51; growth has begun. The cyto- 

 plasm and nucleus have undergone some changes. X 1150. 



53 Growing egg of considerable size, but not full grown. Cytoplasm filled 

 with degenerating nuclei of absorbed oocytes. Germinal vesicle shown. X 1150. 



54 Mature egg showing germinal vesicle; entoplasm of egg much vacuolated 

 and containing chromatin grains, germinal vesicle contains small nucleolus and 

 chromatin bodies. X 1150. 



55 Reconstruction of stomach and growing eggs of one medusa; pseudopodia 

 of eggs and the tiny germinal vesicles are shown; the oocytes which fill spaces 

 between growing eggs not represented. 



640 



