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Oscillaria rubiginosa. Garmichael Alg. App. ined.
Stratum gelatinous, dark purple; trichomes very thin, straight,
indistinctly articulated, laid on a thin, compact, greenish substratum
.
S iz e . Threads -OOd-'OOdS mm. diam.
Oscillaria violacea, Rabh. Alg. Eur. ii., 113. Eng. Fl. v.
377.O
scillatoria violacea, Hass. Alg. 254, t. 72, f. 10. Harv.
Man. 166. Johnst. El. Berw. ii., 264.
Conferva mucosa confragosa rivulis innascens, Dillen (?)
Rapid streams, and on stones at the bottom of rivers.
When dry the filaments of this speoies assume a blackish green cast,
with an evident gloss. Striæ when dried almost invisible, at a distance
of about two diameters from each other.—Hassall.
As another speoies is called Oscillaria violaoea (Wallr), which has
priority, the name proposed by Carmichael must be adopted.
Plate XCFIII. fig. 6. Portions of trichomes X 400, from the original
specimens.
Osc illazia su b fu sca . Vauch. Conf. 193, t. 15, f . 5.
Forming a very thin, greenish brown, then blackish stratum,
shortly radiating. Trichomes equal, straight, curved at the
apex (curvature of 4 to 5 joints), joints about equal in length to
their breadth (after division shorter), dissepiments very distinctly
granulate, extreme apical point fimbriate, or bearded.
Cell-contents pale greenish steel-blue, granular.
Siz e . Threads 'OOdh-'OOfi mm. diam.
Rabh. Alg. Eur. i., 100. Kirch. Alg. Sohl. p. 246. Mack.
Hib. p. 240. Eng. El. v., 377. Harv. Man. 166.
Oscillatoria subfusca, Hass. Alg. 253, t. 72, f. 9.
Attached to wood, rocks, stones, &c., in streams.
“ Stratum extensive, soft, slimy, void of tenacity, -wrinkled, of a
dusky grey colour, when dry greyish-brown, streaked with green to-
wards the edges ; filaments very slender, striæ invisible.”—llarvey,
Plate XCVI. Jig. 7. Portions of trichomes X 400.
Oscillavia æ rugescens. Drumm. Ann. Nai. Hist. (1838) i,p . 1.
Stratum of a fine deep green, highly gelatinous, when dried
æruginous blue, and glossy ; trichomes very slender, opaque
green, conglomerated in large masses, rarely floating, or broken
into fragments and suspended like cloudy flocculi in the water,
joints about half their diameter long.
S iz e . Trichomes '005 mm. diam.
Oscillatoria oerugescens, Hass. Alg. 249, t. 72, f. 2. Harv.
Man. 163.
In lakes and poola.
This is the speoies which Dr. Drummond described as the “ colouring
substance of Glasslough Lake, Ireland.” He commences by stating that
“ Glas-lough” signifies “ green lake,” an appellation given to it from
time immemorial on account of the hue of its waters, which exhibit a
green tinge, equal to, or exceeding in intensity, that of the sea, though
it is not at all times equally striking. “ From the accounts I received,
the green colour is evident in the lough throughout the year, and if I
may judge from my own observations, every drop of it is impregnated
with the oscillatory filaments.” “ When a little of the water is lifted in
the hand it seems perfectly transparent, and it appears equally clear at
the edges of the lake, but at a depth of two feet the bottom is indistinguishable,
and the water presents a sort of feculent opacity, accompanied
by a dull, dirty, greenish hue. On lifting some of this in a glass
it seems at first sight quite transparent, but on holding it up to the light
innumerable minute flocculi are seen floating through every part of it,
and producing a mottled cloudiness throughout the whole.” “ At first I
could only find the plant diffused through the water, but at length I discovered
a wet ditch extending fi om the lake into an adjoining field, and
there it appeared swimming on the surface in large masses several inches
ill thickness, and above a foot and a half in length. These seemed evi.
dently to be produced by an agglomeration of the filaments floated in
from the lake, matted together at the surface, and increased in growth.
The surface of these masses, where dried by the contact of the air, was
of a bright bluish verdigris hue, while the parts immersed in the water
were of a dull opaque green.
“ On examining specimens in the microscope, I sometimes observed
their motions to be very vivid, and in other instances little or no motion
could be perceived. They are extremely minute, their transverse striæ
very numerous, and at distances of about half a diameter from each
other. The filaments in the conglomerated masses appeared to me to be
many inches long, and running parallel together ; the broken fragments
dispersed through the lake cross each other in all directions.”
Plate XCVlll. fig. 5.
Trichomes from specimen collected by Drum-
mond X 400 diam.
Oscillaxia t e n u is . Ag. Syst. Alg. p. 60.
Forming a brig h t green, or dark blue green stratum, shortly,
or elongated radiating. Trichomes straight, rather rigid, more
or less endowed with active motion ; joints equal or half as
long as broad, sometimes a little constricted at the dissepiments,
which are delicately granulated ; apex more or less
attenuated, obtuse, curved or s tr a ig h t; cell-coiitents pale
watery blue.
S iz e . Threads '054--006 mm. diam.
Rabh. Alg. Eur. i., 102.
Oscillatoria limosa. Hook El. Soot, ii., 79.
Oscillaria viridis, Kutz. Tab. Phyo. i., t. 41, f. 6 . Eng. Bot.
t. 2523. Johnst. Fl. Berw. ii., 264.
Oscillatoria contexta, Carm. Hass. Alg. 256, t. 71, f. 7, 4,
6 . Eng. El. V., 876. Harv. Man. 165.
Oscillatoria tenuis, Hass. Alg. 248, t . 72, f. 1. (?) Jenii.
Tunb. Wells 188. Harv. Man. 163. Grev. Fl. Edin. 803.
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