The English flora - SeaweedAfrica

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2 ALCkffi CONFERVOIDE^:. [OsciUatoria.
spection I could make, the filaments in the two following species
are cylindrical and not articulated but merely contracted
at certain equal distances into a series of imperfect or pervious
cells, each including- a couple of sporidia. These contractions
form the only essential difference between this genus and
Lyngbya." Carm. MSS.
1. R. le?itigera, Carm. {short-jointed Rosaria); locules strongly
contracted, as long' as broad, sporidia lenticular.
On various small Algce. Appin, rare, Captain Carmichael.— " Filaments
gregarious, 1— 2 lines in length, curved, of an olive colour, regularly
contracted at equal distances to one-fourth of the diameter of the tube;
celteas long as broad, containing two fentiform sporidia. At first, the
sporidia are in one mass, marked only by a transverse stria." Carm.
MSS.
2. R. globifera, Carm. (long-jointed Rosaria); locules subcon-
tracted twice as long as broad, sporidia globular.
On Utva ? percursa ; extremely rare. Appin, Capt. Carmichael.—
"Filaments scattered, 1—2 lines in length, of a fulvous colour, not above
half the diameter of the preceding species. Cells slightly contracted,
twice as long as broad, containing two globular sporidia." Carm. MSS.
76. OseiLLAToitiA.i Vaach. OsciUatoria.
Filaments invested by a common mucous matrix, rigid, elas-
] Captain Carmichael has the following ingenious remarks under OsciUatoria,
in his unpublished "Alc/ce Appinenses." " I have been induced to bestow considerable
attention on such of the species as fell under my notice, on account of
the singular motion remarked in the filaments by various Naturalists ; and I
do confess, that the result is something like conviction that they belong rather
to the animal than to the vegetable kingdom. This motion or oscillation has
been attributed to various causes; to the rapidity of growth, to the action of
the light, or to the agitation of the water in which the specimens were immersed
for inspection; but none of these affords a satisfactory explanation :
the last may be put to the proof by a very simple contrivance. Let a small
portion of the stratum be placed in a watch-glass nearly filled with water, and
covered with a circular film of talc, so that its edge may touch the glass ; the
water will be rendered as fixed as if it was a piece of ice. The glass may now
be placed under the microscope, and the oscillation of the filaments viewed
without any risk of disturbance from the agitation of the water ; by following
this course, it will be speedily perceived that the motion in question is entirely
independent of that cause.
" The action of light, as a cause of motion, cannot be directly disproved, because
we cannot view our specimens in the dark; but indirectly there is nothing
easier. If a watch-glass, charged as above, be laid aside for a night, it
will be found that by next morning, not only a considerable radiation has
taken place, but that multitudes of the filaments have entirely escaped from the
stratum; both indicating motion independent of light. Rapidity of growth
will show itself in a prolongation of the filaments, but will not account for this
oscillation to the right and left : and still less for their travelling in the course
of a few hours to the distance often times their own length from the stratum.
This last is a kind of motion, unexampled, I believe, in the vegetable kingdom.
There is another point in the natural history of the OsciUatoria., which favours
the opinion that they are animalculse. It is the extremely limited term of their
existence. The community, if I may so call it, lives for several months; but
the individuals die off", and are succeeded by others with a rapidity to which
there is no parallel among genuine plants. If a small portion of stratum, say
one-fourth of an inch in diameter, be left for 3 or 4 days in a watch-glass, filled
with water, the whole area of the glass will be found covered with a thin
transparent pellicle or incipient stratum, derived from the filaments that had
successively radiated and died in the course of that short period."