Smira, — Gastrulation in Aurelia, 
ia 
8. 
9. 
10. 
11. 
12. 
PLATE IL 
ABBREVIATIONS. 
bl’ po. Blastopore. 
cav. 8g. Segmentation cavity. 
cl. Immigrated cell. 
coclent. Coelenteron, 
cog. Coagulum. 
ec’drm. Ectoderm. 
en’drm. Entoderm. 
nl. Chromatic portion of degenerated nucleus. 
nl. ece’drm. Nuclei of deeper portion of ectoderm. 
Figures 7, 9, and 10 are from different sections of the same individual. 
Fig. 
Section through the blastoporic canal and nearly perpendicular to it. 
x 410. 
Section at a stage preceding invagination. It shows an immigrated cell 
in which the nucleus has degenerated. X 385. 
Section before the close of gastrulation, showing an immigrated cell in 
the segmentation cavity. X 410. 
Section from the same individual as Figure 9. It contains an immigrated 
cell in the colenteric cavity. X 410. 
Section of a gastrula with two immigrated cells contained in the colen- 
teric cavity. X 385. 
Section from the same individual as Figure 3, to show the appearance 
when the gastrula is cut parallel to, but at one side of, the blastoporic 
canal. X 885. 
