ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
469 
which are the nucleus and protoplasm. The stalk is connected with the 
supporting lamella. 
The subepithelial tissue consists of ganglionic, sexual, and indifferent 
cells, the last of which give rise to the others and to the stinging cells. 
The ganglionic cells have a small nucleus, but no nucleolus, a small 
quantity only of protoplasm and long branching processes, which become 
varicose on treatment with acetic acid. These processes become con- 
nected with one another, with the epithelio-muscular cells, and probably 
also with the stinging cells. The spermatozoa have a cylindrical head, 
a transversely flattened middle piece, and a long, thin flagellum. The 
indifferent cells are rounded, cubical, or somewhat cylindrical, and have 
a nucleus of medium size, together with a nucleolus. 
The stinging cells are derived from the indifferent by the central 
secretion of an alkaline product which is first surrounded by the inner 
wall, and by the outer only when the formation of the filament ceases. 
The filament is probably formed by the surrounding protoplasm growing 
into the secretion-cavity. The ganglionic cells are formed from the 
indifferent by the using up of the central part of the cell at the expense 
of the peripheral, which takes on a semilunar form and grows out into 
processes. The spermatozoa are formed by repeated indirect division of 
the indifferent cells. 
The endoderm is likewise formed of epithelial and sub-epithelial 
cells. The former are epithelio-muscular, or nutrient, glandular, and 
sensory cells ; in some of the first there are stinging-capsules. The 
epithelio-muscular cells have two (rarely three or one) flagella. They 
excrete basally a contractile fibre, which takes a circular course, and is 
less well developed than in the ectoderm. The processes into the sup- 
porting lamella are also more delicate. In the interior there are nutrient 
bodies, and brownish or reddish pigment ; they multiply by indirect 
division. The glandular cells have two or three flagella ; are shortly 
oval, and are rarely provided with a prolongation at their basal end ; 
they have in their interior a highly refractive secretion which fills the 
protoplasm in the form of rounded balls. The sensory cells are fila- 
mentar, but somewhat thickened peripherally ; they have an elongated 
nucleus and a short hair on the surface ; at their base they break up 
into varicose processes ; they would appear to be derived from epithelio- 
muscular cells. The stinging capsules appear to have no nucleus, and 
we cannot, therefore, suppose that they are directly derived from the 
nutrient cells. The ganglionic cells agree exactly with those in the 
ectoderm. They are derived from the sensory cells, as intermediate 
stages between them may be observed. The indifferent cells are like 
those of the ectoderm, but are much rarer. 
The supporting lamella is a homogeneous intermediate layer between 
the ectoderm and endoderm, but is much more closely connected with 
the former. 
In an appendix Herr Schneider deals with some of the histological 
elements of Eudendrium ramosum and Tubularia larynx. Their ganglionic 
cells correspond in form and position almost exactly with those of Hydra 
f usca , but the number of processes is smaller and the processes themselves 
are finer ; the nucleus has a nucleolus ; the processes of the cells were not 
observed to be connected wfith one another or with epithelial cells. The 
