is
filled with water and placed in a saucer filled with sand. A strip of
blotting paper about the width of the slide is now placed with one end
in the water, the other hanging over the edge of the glass and against
one side of a slide, which is thus held upright, but must not be
allowed to touch the side of the tumbler. The strip of blotting paper
sucks up the water, which flows slowly down the surface of the slide
in contact with the blotting paper. If now a bit of the substance upon
which the plasmodium is growing is placed against the bottom of the
slide on the side where the stream of water is, the protoplasm will
creep up against the current of water and spread over the slide,
forming delicate threads in which most active streaming movements of
the central granular protoplasm may be seen under the microscope, and
the ends of the branches may be seen to push forward much as we saw in
the amoeba. In order that the experiment may be successful, the whole
apparatus should be carefully protected from the light, and allowed to
stand for several hours. This power of movement, as well as the power
to take in solid food, are eminently animal characteristics, though
the former is common to many plants as well.

After a longer or shorter time the mass of protoplasm contracts and
gathers into little heaps, each of which develops into a structure
that has no resemblance to any animal, but would be at once placed
with plants. In one common form (_Trichia_) these are round or
pear-shaped bodies of a yellow color, and about as big as a pin head
(Fig. 5, _D_), occurring in groups on rotten logs in damp woods.
Others are stalked (_Arcyria_, _Stemonitis_) (Fig. 5, _J_, _K_), and
of various colors,--red, brown, etc. The outer part of the structure
is a more or less firm wall, which breaks when ripe, discharging a
powdery mass, mixed in most forms with very fine fibres.

When strongly magnified the fine dust is found to be made up of
innumerable small cells with thick walls, marked with ridges or
processes which differ much in different species. The fibres also
differ much in different genera. Sometimes they are simple,
hair-like threads; in others they are hollow tubes with spiral
thickenings, often very regularly placed, running around their
walls.

The spores may sometimes be made to germinate by placing them in a
drop of water, and allowing them to remain in a warm place for about
twenty-four hours. If the e