PLATE I. 



Figs. 1-8, 10 and 11 Uerue oiahi. 

 Fig. 9 l'"iicli(iris ))iuUicor)iin. 



Figs. 1, 2 and 3. Three successive stages of tbe division of tlie first [lolocyto. x270. 

 Fig. 4. Surface view of three polocytes. Clear spot indicates tlie egg-nnclens. 



x270. 

 Fig. 5- Sperm-head in thi- egg (surface view). Notice an aster around the centre 



and a réfringent body situated a little apart from the sperm-head. x270. 

 Fig. 6. Side view of an ectoplasmic acciunnlation caused hy the spermatozoon. 



X27(). 

 Fi-g 7- Tbc same drawn from a Polyspermie egg. x 270. 

 Fig. 8. Trispermic egg (surface view). xGO. 

 Fig. 9. Dividing egg of Kucltaiis (optical section), a stage preceding Figs 23 and 



24 (PL II), 3.23 P.M. xl40. 

 Fig. 10- Dividing egg, the cleavage having proceeded nearly one third the diameter. 



xCO. 

 Fio- 11- Dividing egg, showing outlines of four stages ; a-a' 10 A.M., h 10.8 A.M., 



e-c' 10.2.5 A.M., and d-d' 10 3.5 A.M. xGO. 



