186 
J. BRONTE GATENBY. 
Fig. 8. — Part of egg mass of Donacia in transverse section showing a 
parasite at the stage drawn in fig. 28. 
Fig. 9. — Nearly mature ovarian egg of parasite to show nucleus (N.y 
and germ cell determinant (G. C. D.). 
Fig. 10. — Newly-laid egg, with spermatozoon (M. P. N.). 
Fig. 11. — Formation of second polar body. 
Fig. 12. — Typical blastoderm stage showing extruded nuclei (EX. N .) 
and germ cells ( G . C.). 
Fig. 13. — Later blastoderm to show stages in nuclei and shortening 
of egg. 
Fig. 14. — Late blastoderm stage showing beginning of formation of 
endoderm (N. S. I.). 
Fig. 15. — Stage after fig. 14 to show beginning of insinking of 
peripheral nuclei (x Y.), and penetration and change of position 
of germ cells. 
Fig. 16. — Part of transverse section of blastoderm stage to show 
structure of nuclei. 
Fig. 17. — Transverse section of a blastoderm stage to show expulsion 
of nuclei (Y.). 
Fig. 18. — Transverse section showing final extrusion of nuclei 
(EX. N.) and beginning of gastrulation. 
Fig. 19. — Gastrula stage in transverse section after expulsion of 
nuclei (EX. N.). Nuclei in this specimen a little larger than usual. 
Fig. 20. — Transverse section of posterior pole of the same egg as 
that in fig. 7, to show germ cell determinant. 
Fig. 21. — Posterior pole of blastoderm stage to show germ cells 
(G. C.) and structure of nuclei. 
Fig. 22. — Posterior pole of egg just after sinking inwards of germ 
pocket (G. C. P .) and when the nuclei (X. X.) form a covering for 
the pocket. 
Fig. 23. — Transverse section of same embryo as that in figs. 24, 25, 
and PL 12, fig. 31, to show germ cells. Such a section as this is 
through the points A ... A in PI. , fig. 15. 
Fig. 24. — Transverse section of embryo during the formation of gut 
(END. N.) and nervous system (N. C.), etc. 
Fig. 25. — Section through anterior region near stomodseum. 
Fig. 26. — Enlarged view of posterior pole of the egg drawn in fig. 11, 
to show breaking up germ cell determinant (P. P.). 
Fig. 27. — Obliquely sagittal section through embryo to show forma- 
tion of gut (G. T.), stomodseum (STD.), proctodseum, brain, and nerve 
chord. 
