PLATE 8 



EXPLANATION OF FIGURES 



40 Ctenolahrus adspersus 9 X Fundulus heteroclitus cf. The spindle from a 

 three-celled polyspermic egg. The chromatin on the spindle is disintegrating. 



41 Ctenolahrus adspersus 9 X Fundulus heteroclitus cf. Mitotic figures 

 from a sixteen-hour blastoderm. Separate chromosomes cannot be distinguished. 

 No lagging of chromatin noted. 



42 Similar figures from a thirteen-hour blastoderm of Ctenolahrus 9 X 

 Ctenolahrus c?. 



43 Ctenolahrus adspersus 9 X Fundulus heteroclitus c^. Resting nuclei from 

 a sixteen-hour blastoderm showing the single nucleolus characteristic of regularly 

 divided hybrid eggs. 



44 Resting nuclei from a thirteen-hour blastoderm of Ctenolahrus 9 X Cteno- 

 lahrus cf , showing the normal binucleolate condition. 



45 Ctenolahrus 9 X Ctenolahrus d'. Part of a section through a normal 

 thirteen-hour blastoderm. This drawing shows the frequency with which nuclei 

 containing two nucleoli occur in the sections. Magnification not recorded. 



278 



