378 Davis . — On Euglenopsis : a New 
Since the structure of this organism is peculiar and most 
readers are not likely to have ever met with a similar form, 
it will be much easier to make the description clear if the 
reader will first glance at Plate XIX. In Fig. i is shown 
a well-developed specimen magnified about 250 diameters. 
From this figure one may get a very fair idea of the habit of 
the plants, which are all small, the larger specimens being 
about one-fourth of a millimeter high. As may readily be 
seen, certain green cells are situated at the ends of a branching 
filament or stalk, and this branching filament consists of 
empty cell-cavities or compartments arranged in a moniliform 
manner. 
The wall of the filament is hyaline and thin, but elastic, 
and so firm that it shows no tendency to collapse, and so 
flexible that the filament quickly regains its former shape 
when it has been bent. It is entirely unaffected by boiling 
in a strong solution of potassic hydrate, which proves that it 
is not of a gelatinous nature. While the wall does not give 
the cellulose-reaction with iodine and concentrated sulphuric 
acid, nevertheless its behaviour when treated with other re- 
agents shows it to consist, if not actually of cellulose, of 
a substance closely related to cellulose. It dissolves in 
the most concentrated sulphuric acid, and can be stained 
slightly by iodine and readily by haematoxylin and certain 
anilin-dyes. 
When it is stated that the cell-cavities in the lower 
portions of the filament are empty, it is meant that they 
are free from any protoplasmic matter. They also contain 
no bubbles of gas, and it is but reasonable to suppose 
that the fluid in their interior is the brackish water of the 
salt-marshes. 
Passing now to the green cells at the ends of the branches 
of the filament, we find, beginning with the exterior of the 
cell, that the protoplasm is surrounded by a thin, hyaline, 
firm wall, that is similar to and continuous with the wall of 
the filament below it. The protoplasmic mass inside the 
wall (see Fig. 2 in particular, and also Figs. 8 and 12) is 
