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.