No. 3.] DEVELOPMENT OF MARINE SPONGES. 341 
find any more, my conclusion is that these anchors are foreign 
particles, and that bits of the sponge to which they originally 
belonged entered Tedanione and were used as food. 
2. DEVELOPMENT. 
My observations on the development of Tedanione and Hir- 
cinia deal only with the egg development, going in the former 
sponge as far as the formation of the swimming larva, but in 
the latter no farther than the segmentation. 
Tedanione was with eggs in September and October and 
possibly for a much longer time at Green Turtle Cay, Bahamas. 
Adults were kept in aquaria, and after an hour or two, as a 
rule, a few ciliated larvae were thrown out of the oscula. 
The very young ovarian egg is of an irregular shape and lies 
in the mesoderm surrounded by a follicle of flattened cells, 
Pl]. XXIII, Fig. 102, ov.0. It has a large nucleus and single 
nucleolus. As the egg increases in size it becomes rounded, 
its protoplasm becomes filled with yolk, and the nucleus 
undergoes certain changes, which are not completed until the 
ege has attained its full size and is ready for segmentation. 
A general idea of the change in size and character of the egg 
during its growth may be gathered from a comparison of PI. 
XXIII, Figs. 102, 103, 104, 105, 106, drawn to the same scale 
and representing successive stages in the life of the egg. 
During the increase in the size of the egg, its follicle is 
constantly surrounded by a dense mass of mesoderm cells, as 
may be seen in the section, Fig. 103 (mes. =the cells in ques- 
tion; the egg is one-half the full size). These cells have large, 
plump bodies which stain well, being full of a finely granular 
yolk. The shape and direction of the cells on the outskirts of 
the mass indicate a migration of mesoderm cells from all 
quarters to the egg. By the time the egg has reached its full 
size the surrounding mass of cells has dwindled away to a 
small number, Fig. 104, and during the remaining period of 
its life in the parent sponge the embryo is surrounded by 
ordinary mesoderm, in which the cells are not more thickly 
crowded than elsewhere in the body. It is only while the egg 
