Fig. 
‘ 
Samira. — Gastrulation in Aurelia, 
1. 
pw» 
PLATE I. 
ABBREVIATIONS. 
bl’ po. Blastopore. 
cav. sq. Segmentation cavity. 
Cl Immigrated cell. 
ceelent. Coelenteron. 
cog. Coagulum. 
ec’drm. Ectoderm. 
en’drm. Entoderm. 
nl, Chromatic portion of degenerated nucleus. 
nl. ec’drm. Nuclei of deeper portion of ectoderm. 
Figures 1-4. Sections to illustrate the nature of the invagination. 
An early stage of invagination. 460. 
A slightly later stage than that of Figure 1. x 540. 
A stage in which the invagination is well advanced. 885, 
A gastrula with invagination completed. 410. 
Section of a gastrula cut in a plane (equator) perpendicular to the axis of 
the blastoporic canal. X 385. 
Section of an older individual through the equator, showing increase in 
thickness of the entoderm. x 885. 
