ists changes of temperature to a
remarkable degree. _Vaucheria_ affords a choice hunting ground to the
microscopist, for its tangled masses are the home of numberless infusoria,
rotifers, and the minuter crustacea, while the filaments more advanced in
age are usually thickly incrusted with diatoms. Here, too, is a favorite
haunt of the beautiful zoophytes, _Hydra vividis_ and _H. vulgaris_, whose
delicate tentacles may be seen gracefully waving in nearly every gathering.

REPRODUCTION IN VAUCHERIA.

After the plant has attained a certain stage in its growth, if it be
attentively watched, a marked change will be observed near the ends of the
filaments. The chlorophyl appears to assume a darker hue, and the granules
become more densely crowded. This appearance increases until the extremity
of the tube appears almost swollen. Soon the densely congregated granules
at the extreme end will be seen to separate from the endochrome of the
filament, a clear space sometimes, but not always, marking the point of
division. Here a septum or membrane appears, thus forming a cell whose
length is about three or four times its width, and whose walls completely
inclose the dark green mass of crowded granules (Fig. 1, b). These contents
are now gradually forming themselves into the spore or "gonidium," as
Carpenter calls it, in distinction from the true sexual spores, which he
terms "oospores." At the extreme end of the filament (which is obtusely
conical in shape) the chlorophyl grains retract from the old cellulose
wall, leaving a very evident clear space. In a less noticeable degree, this
is also the case in the other parts of the circumference of the cell, and,
apparently, the granular contents have secreted a separate envelope
entirely distinct from the parent filament. The grand climax is now rapidly
approaching. The contents of the cell near its base are now so densely
clustered as to appear nearly black (Fig. 1, c), while the upper half is of
a much lighter hue and the separate granules are there easily
distinguished, and, if very closely watched, show an almost imperceptible
motion. The old cellulose wall shows signs of great tension, its conical
extremity rounding out under the slowly increasing pressure from within.
Suddenly it gives way at the apex. At the same instant, the inclosed
gonidium (for it is now seen to be fully formed) acquires a rotary motion,
at first slow, but gradually increasing until it has gained considerabl