164 Proceedings of the Royal Society of Edinburgh. [Sess. 
Fig. 3a. A cell from an egg containing sixteen cells. x 1000. 
Fig. 3b. A cell from the yolk at the period when the newly formed blastoderm 
presents a crenate outline (see p. 158). x 1000. 
Fig. 4. Yitellophag transformed into a yolk-ball. x 1000. 
Fig. 5 a. Cells of the ventral plate, the amnion, and the serosa drawn from the 
same egg as fig. 6c, but from a section nearer to the cephalic border of the ventral 
plate. x 500. 
Fig. 55. Greatly narrowed and elongated cells of germ-rudiment, and flattened 
amnion cells from the same preparation as fig. 8c. x 500. 
Figs. 6a, 7 a, 8a, and 9a were drawn from living eggs. Explanation in the text, 
pp. 161-163. x 60. 
Figs. 65, 75, 85, and 95 show approximately corresponding embryos after 
fixation. x 60. 
Fig. 65. The fully formed ventral plate, dorsal aspect. 
Fig. 75. The germ-rudiment, dorsal aspect about two hours older. Its edges are 
rolling inwards, while the longitudinal axis increases somewhat in length. 
Fig. 85. The germ-rudiment has assumed a pouch form, and has rotated through 
90 degrees to the left (lateral aspect). 
Fig. 95. The embryo changing into the “ germ-band ” (lateral aspect). 
Fig. 105. A germ-band with dextral aspect. x 60. 
Fig. 115. A sinistrally turned germ-band seven days after oviposition. The 
inner layer has segmented. x 60. 
Fig. 6c. Transverse section of an egg (cf. fig. 65) to show the origin of the 
amnion and its relation to the ventral plate and the serosa (see p. 160). In this and 
the following figures the dorsal surface is uppermost. x 200. 
Fig. 7c. Transverse section of a slightly more advanced stage than fig. 75, the 
embryo beginning to rotate (see p. 161). x 200. 
Fig. 8c. Transverse section of the stage represented by fig. 85 (see p. 162). x 200. 
Fig. 9c. Transverse section of the same stage as fig. 95, showing the medium 
groove and the inner layer. x 200. 
Fig. 10c. Transverse section of an embryo in the same stage as fig. 105. x 200. 
BIBLIOGRAPHY. 
Bobretzky, K., “ Ueber die Bildung des Blastoderms und der Keimblatter bei 
den Insekten,” Zeits. Wiss. Zool., Bd. xxxi, 1878. 
Bruce, Adam, Observations on the Embryology of Insects and Arachnids, 
Baltimore, 1887. 
Graber, V., “ Yergleichende Studien am Keimstreifen der Insekten,” Denkschr. 
Acad. Wiss. Wien, Bd. Ivii, 1890. 
Hallez, P., “ Sur la loi de l’orientation de Fembryon chez les Insectes,” 
G.R. Acad. Sci. Paris, t. ciii, 1886. 
Henking, H., “ Untersuchungen fiber die ersten Entwicklungsvorgange in den 
Eiern der Insekten,” Zeit. Wiss. Zool., Bd. xlix, 1889, and Bd. liv, 1892. 
Herold, M., EntwicJclungsgeschichte der Schmetterlinge , Kassel und Marburg, 
1815. 
