ON THE CTENOPHORE EGG 



9 



them is represented in Fig. 16. This strikingly resembles embryos 

 developed from two end-cells of the 16-cell stage deprived of the 

 first micromeres (Figs. 12, 13). 



In comparing the above results it may be concluded that in the 

 middle-cell the development of comb-plates is arrested in some cases. 

 The difference in behavior between the end- and middle-cells can 

 hardly be due to that of the degree of injury, if any, received at the 



u 



Figs. 7—16. x60. 



Figs. 8 and 9, embryos from E (Fig. 7); Eig. 11, embryos from -V. 

 (Fig. 10); Fig. 13, embryo from 2E— 2e, (Fig. 12); Fig. 15, embryo with two 

 comb-rows developed from 2M (Fig. 14) ; Fig. 16 combless embyro from 2M. 



