ontaining the spores. The whole should be
kept under cover so as to prevent loss of water by evaporation. By
this method the spores may be examined conveniently without
disturbing them, and the whole may be kept as long as desired, so
long as the blotting paper is kept wet, so as to prevent the
suspended drop from drying up.

CLASS II.--_Schizophytes_.

The Schizophytes are very small plants, though not infrequently
occurring in masses of considerable size. They are among the commonest
of all plants, and are found everywhere. They multiply almost entirely
by simple transverse division, or splitting of the cells, whence their
name. There are two pretty well-marked orders,--the blue-green slimes
(_Cyanophyceae_) and the bacteria (_Schizomycetes_). They are
distinguished, primarily, by the first (with a very few exceptions)
containing chlorophyll (leaf-green), which is entirely absent from
nearly all of the latter.

The blue-green slimes: These are, with few exceptions, green plants of
simple structure, but possessing, in addition to the ordinary green
pigment (chlorophyll, or leaf-green), another coloring matter, soluble
in water, and usually blue in color, though sometimes yellowish or
red.

[Illustration: FIG. 6.--Blue-green slime (_Oscillaria_). _A_, mass of
filaments of the natural size. _B_, single filament, x 300. _C_, a
piece of a filament that has become separated. _s_, sheath, x 300.]

As a representative of the group, we will select one of the commonest
forms (_Oscillaria_), known sometimes as green slime, from forming a
dark blue-green or blackish slimy coat over the mud at the bottom of
stagnant or sluggish water, in watering troughs, on damp rocks, or
even on moist earth. A search in the places mentioned can hardly fail
to secure plenty of specimens for study. If a bit of the slimy mass is
transferred to a china dish, or placed with considerable water on a
piece of stiff paper, after a short time the edge of the mass will
show numerous extremely fine filaments of a dark blue-green color,
radiating in all directions from the mass (Fig. 6, _a_). The filaments
are the individual plants, and possess considerable power of motion,
as is shown by letting the mass remain undisturbed for a day or two,
at the end of which time they will have formed a thin film over the
surface of the vessel in which they are kept; and the radiating
arrangement of the filaments can then be plainly seen.

If the mass