Hareirr: Pennaria tiarella and Tubularia crocea, 
PLATE 8. 
Tubularia crocea. 
Fig. 61. Early cleavage similar to Figure 60, but with equatorial cleavage 
furrows already started. Corrosive-acetic, iron hematoxylin. 
x dl. 
Fias. 62a, 62b. Two sections of one egg, which contained 30 nuclei, similar 
to Figure 61. The elongated shape of the egg is probably due to 
pressure in the gonophore. Pseudo-cells not represented. Cor- 
rosive-acetic, picro-hematoxylin.  X 5l. 
Fig. 63. Blastula composed of 40—50 cells. Some of the spindles are radial, 
indicating the beginning of a primary delamination. The result 
is the formation of the germ layers and the obliteration of the 
segmentation cavity. Pseudo-cells still abundant, but not 
shown. Corrosive-acetic, iron hematoxylin.  X 51. 
Figs. 64,65. To show nuclear proliferation and the beginning of cytoplasmic 
division. The drawings represent the middle sections of two 
eggs upon which all nuclei are projected. In Figure 64 nuclei 
in four pairs on one side of the egg; a polar cell (cl. pol.) and cyto- 
plasmic furrow occur at the same pole. In Figure 65 the nuclei 
are more scattered. Zenker’s fluid (Fig. 64), Flemming’s fluid 
(Fig. 65). Iron hematoxylin and Congo red.  X 51. 
Fic. 66. An egg from the same polyp as the preceding, with a more regular, 
though unequal, cleavage. Zenker’s fluid, iron hematoxylin 
and Congo red. X 51. 
Fic. 67. Late stage in nuclear proliferation, cytoplasmic division in progress; 
a segmentation cavity present. Flemming’s fluid, iron hema- 
toxylin and Congo red.  X 51. 
Fig. 68. Very late stage, in which a solid mass of cells is present; cytoplasmic 
division still retarded. Zenker’s fluid, iron hematoxylin and 
Congo red.  X 51. 
Fic. 69. More regular cleavage, in which the segmentation cavity is being 
filled by cells,—a part of the process of germ-layer formation. 
Corrosive-acetic, Ehrlich’s hematoxylin and eosin.  X 51. 
Fic. 70. Blastula double, perhaps the result of an uncompleted first cleav- 
age. Germ layers forming. Pseudo-cells still abundant, but . 
not shown. Corrosive-acetic, picro-hematoxylin. X 51. 
