Fig. 2a. Portion of same blastoderm highly magnified, to shew the characters of the nuclei of the yolk n´ and the nuclei in the cells of the blastoderm.
Fig. 2b. Large knobbed nucleus from the same blastoderm, very highly magnified.
Fig. 2c. Nucleus of yolk from the same blastoderm.
Fig. 3. Longitudinal section of blastoderm of same stage as fig. 2. (Hardened in chromic acid.)
Fig. 4. Longitudinal section of blastoderm slightly older than fig. 2. Magnified 45 diameters. (Hardened in osmic acid.)
It illustrates (1) the characters of the epiblast; (2) the embryonic swelling; (3) the segmentation cavity.
Fig. 5. Longitudinal section through a blastoderm at the time of the first appearance of the embryonic rim, and before the formation of the medullary groove. Magnified 45 diameters.
Fig. 5a. Section through the periphery of the embryonic rim of the blastoderm of which fig. 5 represents a section.
Fig. 6. Section through the embryonic rim of a blastoderm somewhat younger than that represented on Pl. 8, fig. B.
Fig. 7. Section through the most projecting portion of the embryonic rim of a blastoderm of the same age as that represented on Pl. 8, fig. B. The section is drawn on a very considerably smaller scale than that on fig. 5. It is intended to illustrate the growth of the embryonic rim and the disappearance of the segmentation cavity.