508 
Philippine Journal of Science 
1919 
to form planes of contact with the walls of opposite and neigh- 
boring gonidia. The thickening of the inner wall of the goni- 
dium, sufficient for contact with the walls of the neighbors, 
extends outward to about the equatorial plane of the gonidiai 
protoplast. From this region outward the walls separate and 
rapidly shade off in thickness, leaving an intercellular space 
between the gonidiai walls and the walls of the somatic layer. 
The anterior walls of the anterior quartet of gonidia round out 
into the anterior intercellular space of the coenobium. 
The terete condition of the coenobia under the margins of the 
cover glasses seems to be due to the absorption of atmospheric 
moisture during the storage of the preparations. The first water 
absorbed seems to be taken up by the cell membranes, particu- 
larly by the intralamellar substance of the somatic and gonidiai 
cell walls, and by the substance in the intercellular coenobial 
cavity. After sufficient water has been absorbed for the com- 
plete expansion of the cell walls, additional water absorbed seems 
to be taken up by the protoplasm and by salts in the vacuoles, 
rendering the specimens unsightly. 
The form and extent of the membranes of the sexual repro- 
ductive cells I have not been able to determine. 
The details of the structure of the somatic protoplasts as they 
occur in the living and the fixed material are yet to be studied, 
and will not be taken up here. 
The full history of the segmentation of the gonidia and the 
metamorphosis of the embryos will likewise be left for future 
study. The material on the type slide was purposely fixed at an 
hour when the characteristic stages of the embryos were present 
in abundance, with the result that stages of segmentation of the 
gonidia are lacking in this batch of material. 
The most distinctly peculiar features of the ontogeny of this 
species appear in Plate II, figs. 13 and 15. These are both from 
slide 1 of the pond F material. Fig. 13 shows a specimen (No. 
27) in which the youngest of seven embryos, in the left upper 
quarter, is in the bowl stage with the gonidia perched on the 
rim of the bowl. The older embryos are in the bullet stage, 
the four in the center and the right upper quarter presenting 
side views, and the two lower ones presenting almost rear polar 
views. In all of these bullet embryos, except the nearer one 
showing a side view, the gonidia are closely packed, and in the 
exceptional case they have begun to separate. 
The bullet embryos are shown on a larger scale in Plate II, fig. 
15, a view of a specimen (28) containing six embryos and one 
