1 8 7 
I hese ridges are continued by the epithelial cells. The homogeneous layer is almost free from 
cells; a few rare cells occur in places. At the base of the tentacle, where its wall is continued 
by the peripheric body wall, the mesogloea contains a number of fibrillar connections between 
ectoderm and entoderm. Here the mesogloea is thinner (PI. I, fig. 13); the fibrillae, unbranched 
over their entire length, give the impression of being protoplasmatic connections with local 
swellings; on the mesogloeal limits they are continued by the bases of the respective epithelial 
cells. I hese fibrillae are not found on the transition of tentacle and oral cone. In some places 
(fig. 13, to the left!) these fibrillae end near the ectoderm and branch into a very fine tissue, 
in a layer parallel with the mesogloeal limit. These branches are too fine to be followed. — 
The entode rm is 12 p. or less; the papillose structure is even more defined than in the 
ectoderm; the diverging epithelial cells are in the periphery only in contact (PI. I, fig. 9). 
Deeply staining glandcells are absent, as well as nematocysts. The nuclei are somewhat larger 
than the ectodermal nuclei, and more rounded. 
Bodywall (PI. I, figs. 14, 15 and 16). The ectoderm is thinner than in the tentacles; 
it contains, together with the numerous Supporting cells with small, elongated nuclei, hyaline 
glandcells, and also deeply staining ones, but the latter are rare and only locally more crowded. 
There is a nervous layer but no muscular layer; the former is very deeply seated and contains 
a small number of nuclei which are exactly like those of the epithelial cells. There are no 
nematocyst-batteries, but a few single nematocysts occur (PI. I, fig. 16 at the bottom). The 
mesogloea varies from 6 p. at the top to 50 p, at the base of the tentacles and is a homogeneous 
layer. In some places cells may be found (PI. I, fig. 14); one or two of these cells, with 
deeply staining round nuclei, are inclosed in oval or round mesogloeal cavities. The entoderm 
is the same as in the tentacles. 
Axis. PI. I, fig. 20 gives a section trough the axial connection with the bodywall. 
Nowhere a cicatrice or groove is to be found in the ectoderm of the bodywall as a rest of 
the formation of the axis. The connecting septum is short and broad. The axis-entoderm is 
the same in structure as that of the bodywall, especially in the shape of the nuclei. The axis- 
ectoderm, which is ontogenetically to be derived from the bodywall-ectoderm, is in structure 
and the shape of the nuclei entirely like the entoderm, probably through the influence of the 
changed function and situation. There are no glandular elements. — The mesogloea is 
very thin, so that the fibrillar bases of ecto- and entoderm leave no homogeneous layer between 
them. The axis itself is concentrically stratified, with alternating layers of a more or less 
refractive substance. The axial canal is surrounded by a brown axis-intima. — The axial epithelial 
layers are continued over the spines, and this sheath of the spines is often tused with the 
entoderm and the mesogloea of the bodywall (PI. V, fig. 21, where the section is made near 
the top of the colony so that the axis fills almost the entire polypar cavity). In PI. V, fig. 19 
the axis-mesogloea is even grown together with the mesogloea of one of the primary mesen¬ 
teries. — The axis-ectoderm is usually thickened at the base of the spines (PI. V, fig. 21). 
Actinopharynx (PI. I, fig. 19; PI. V, figs. 17, 18 and 20). The ectoderm (20 p.) is 
very deeply staining through a layer of small actinopharyngeal glandcells, just below the surface 
of the ectoderm, while there is a large number of nuclei also in the upper two thirds of the 
