has since added it to the British flora, having found it at
Wintcrhourne Stream at LcAves, Sussex; and to him and
Mr. Turner I am indebted for the specimen here figured.
I t groAvs on flint stones in little tufts about a quarter of an
inch ill length, and of a hlnlsh green colour, glossy Avhcn
dry. The filaments, Avhich are repeatedly branched, are
erect, straight, of equal height, and very flaccid and slender
thronghoiit. The branches are placed at uncertain, generally
considerable distances, from each other, and issue from
the stem so as to produce an obtuse angle, but immediately
curve iuAvards, and then rise in a more or less upright direction
; their disposition is far from regular, but they are frequently
disposed on opposite sides in alternate parcels of
tAvo or three. The ramuli are ahvays placed nearer to each
other than the main branches, and I have frequently observed
more than one proceeding from the top of the same
jo in t; they are blunt at their apices; the dissepiments are
rcachly observable Avith a microscope, and divide the filaments
into perfectly cylindrical joints, of Avhich the length is generally
from four to six times greater than the diameter.” —
Dillw.
To the above very accurate description of a most beautiful
production, it is necessary to add but very few words. The
single species of the genus Trentepohlia, like those of the
tAvo preceding genera, seem to find pleasure in pure and
running Avaters, attaching itself to any substance favourably
placed in the current of the stream, and to which it can
firmly adhere. When in health the plant is of a blood-red
colour, a colour which, in decomposition, it readily imparts
to whatever It may he in contact Avith. This colour, however,
is observed to change either by age or habitat, or
some other circumstance connected with its place of growth,
to a bluish grey, in which state it constitutes the Conferva
chalybea of Dr. Both and Mr. Dilhvyn. No difference can
be detected between the filaments of the two states, which
may therefore be concluded to be merely conditions of the
same Alya. The fructification, which adds much to the
beauty and elegance of the plant, is by no means rare.
F am. V. CHABACEÆ.
Char. Stem dichotomous and jointed ; each joint composed
either as in Nitella o f a single cell or tube, or as in Chara
o f a single cell surrounded by other smaller contiguous cells,
which take a spiral direction ; each articulation moreover
is surmounted hy a variable number o f branches three
or fo u r times jointed, which are arranged in the form
o f a verticillum or whorl, and at the joints o f which the
reproductive organs are situated ; these are o f two hinds,
consisting o f nucules and globules. Circulation spiral, and
distinct in each cell.
Following the example of those more recent Algologists
who consider the Characeoe as Algæ, I give this order a prominent
place amongst the British freshwater Algæ, a position
to Avhich they are well entitled, both on the ground of their
greater comparative complexity of structure, and of the high
interest attached to certain phenomena connected Avith their
history.
T h e phenomena more p a rticu la rly alluded to in th e p re ceding
paragraph are tAvofold ; th e first having reference
to th e circulation in th e cells of Avhich th e different species
o f th is order are composed, and th e second to th e existence
o f spermatozoa in th e globules or male blossoms.
These phenomena are confined amongst th e freshwater division
of th e Algæ to th e Characeoe.
I n order th a t th e n a tu re of th e circulation (which Avill first
be considered), carried on in th e ceUs o f th e Characeoe, may be
more clearly understood, it Avill be advisable, previously to
en terin g upon its consideration, to give a general notion of
th e stru c tu re of these curious productions.
The order Characeoe is divided into tAVO genera, Chara
and Nitella. The main stems of the different species of