Text-fios. 2-4. 



Letters CHC = collar-cell of gastral epithelium. EOT and END = ectoplasmic and endo- 

 plasmic regions of oocyte. M= mitochondria. SP = spermatozoon. 



Figs. 2 and 3. — Two stages in the fertilization of Grantia ; in fig-. 2 the spermatozoon (SP) 

 has just entered a collar-cell ; in fig. 3 the collar-cell has lost its collar and ]3 sinking 

 below its fellows. Subsequent stages are drawn on PI. 20. figs. 12, 16, and 17. 



Fig. 4. — Part of an oocyte and the covering-wall of collar-cells (CHC). The black dots 

 represent the comparative positions of twenty-five spermatozoa in that number of 

 cases examined in the stage drawn in fig. 3. In all I have over fifty oocytes in stages 

 at or between Text-figs. 2 & 3 and PI. 20. fig. 11. 



