PLATE 3 



EXPLANATION OF FIGURES 



12 Growing egg from a gonophore of the same colony as those of figures 10 

 and 11. Cytoplasm rather loose and somewhat alveolar with nuclear substance 

 in the cytoplasm. X 1765. 



13 Larger egg from another gonophore of the same region as that of figure 

 12. The cytoplasm is filled with large yolk spheres, and the nuclear substance 

 is still passing into the cytoplasm, though less abundantly than previously. 

 A nucleolus is present in this egg, but was not shown in this section. X 1765. 



14 Male colony. Longitudinal section of stem below the pedicel of a gono- 

 phore, with a small group of germ cells in the entoderm. X 1010. 



15 Male. Longitudinal section of a stem just below the terminal hydranth 

 and above a lateral branch which is forming gonophores. The entoderm con- 

 tains a mass of cells, the deeper ones of which are primitive sperm cells. X 1010. 



16 Longitudinal section through a developing male gonophore showing a 

 group of spermatogonia in the entoderm. X 1010. 



17 to 19 Longitudinal sections through developing male gonophores. The 

 germ cells are shown in the pedicels and in the bodies, more or less scattered 

 in figure 17, but becoming definitely localized in figure 19. X 255. 



