The English flora - SeaweedAfrica

244 CHARACEJE.
gated particles, which possessed double refraction, and had regular
and depolarizing axes." 1
In those species of Cliara which are destitute of the calcareous
incrustation, and even in those which possess it, when that
covering is removed, the movement of the sap has been distinctly
observed and brought into notice by Professor Amici of Modena.
Each joint or distinct tube has its own peculiar circulation, and
the movement was ascertained in C. vulgaris to be at the rate
of 2 lines per minute. M. Blainville witnessed the phenomenon
with Professor Amici, and observes that the microscope brought
to view a movement of 2 liquid currents, the one ascending and
the other descending, circulating in the same tube, without being
separated by any partition which could insulate them. The reality
of this was placed beyond a doubt by the distinct passage of
certain molecules of one of the currents, which, being attracted
by the one which moved in the opposite direction, were occasionally
dragged along with it. 2
Notwithstanding the minute size of the nucules of the Genus,
Cliara, they occur in a fossil state both in the marie deposits in
the lakes of Forfarshire, and in the chalk of Montmartre, where
they are known by the name of Gyrogonites, and were long
considered by naturalists to belong to some extinct testaceous
animals. In the first-mentioned situations, the same species (C
hispidd) has been found also to exist very abundantly in a recent
state in the water which covers the beds of calcareous marie
that include the fossil nucules.
Professor Agardh has divided the Genus into Nitella and
Chara, characterizing the former by its having a single, jointed
tube composed of a very thin colourless membrane, resembling that
of his Genus Valonia, the globules and nucules separated, desti-
tute of bracteas and with scarcely any perceptible prominences or
points crowning the nucules :—whilst, in Chara, the principal tube
is covered by several lesser tubes, (except in the part which is
buried in the mud and in the extremities of the branches,) the
globules and nucules are placed near each other, supported by many
bractese, and the nucules are crowned with distinct teeth. But
the character derived from the simple or compound stems is of
extremely difficult investigation, and that deduced from the
situation of the organs of reproduction does not appear to
be constant.
Species of Chara, scarcely differing from those of Europe,
I have received from almost every part of the world ; from Iceland
in the north (where they sometimes grow in the hot
springs) to the tropics, and in both hemispheres. They are
found carpetting the bottoms of ditches, and stagnant waters, and
frequently yielding a very disagreeable odour. Trout and Carp
1 Ed. Phil. Journ. v. 9. p. 194. 2 Brewster's Ed. Journ. 1827, p. 384. ,