Figs. 1-4. Different stages in the segmentation of the ovum.
Fig. 1. Ovum with a single vertical furrow, from above.
Fig. 2. Ovum with two vertical furrows, from above.
Fig. 3. Side view of an ovum with a completely formed blastodermic disc.
Fig. 4. The same ovum as fig. 3, from below, shewing four vertical furrows
nearly meeting at the vegetative pole.
Figs. 5-10. External views of embryos up to time of hatching.
Fig. 5. Embryo, 3.5 millims. long, third day after impregnation.
Fig. 6. Embryo on the fifth day after impregnation.
Fig. 7. Posterior part of same embryo as fig. 6, shewing tail swelling.
Fig. 8. Embryo on the sixth day after impregnation.
Fig. 9. Embryo on the seventh day after impregnation.
Fig. 10. Embryo on the eleventh day after impregnation (shortly before
hatching).
Fig. 11. Head of embryo about the same age as fig. 10, ventral aspect.
Fig. 12. Side view of a larva about 11 millims. in length, shortly after
hatching.
Fig. 13. Head of a larva about the same age as fig. 12, ventral aspect.
Fig. 14. Side view of a larva about 15 millims. long, five days after
hatching.
Fig. 15. Head of a larva 23 millims. in length.
Fig. 16. Tail of a larva 11 centims. in length.
Fig. 17. Transverse section through the egg-membranes of a just-laid ovum.
We are indebted to Professor W. K. Parker for figs. 12, 14 and 15.