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M ic ro cy stis protogenita. {Bias.) llaih. Alg. Eur. u., 51.
Thallus membranaceous, thin, green; families small, angular
from mutual pressure ; cells small, sphærical ; cell-contents
granular, pale blue-green.
S iz e . Families, '02 mm. Cells, •0015-'002 mm.
Micraloa protogenita, Bias. Alg. Mior. t. xix. Meneg. Nost.
t. xiv., fig. 1 (partly).
In water long standing, stagnant ditches, amongst other
Algæ, &c.
Plate L X X X V I . fig. 5. Families magnified 400 diam.
M ic ro cy stis marginata. {Ueneg.) Kirch. Alg. Schl. 255.
Thallns sphærical, flattened, or orbicular and lens-shaped,
sometimes confluent, pale-green, colourless at the margin ; cells’
minute ; cell contents blue-green, at length granular.
S iz e . Cells 'OOS-'OOI mm. Families '8-03 mm.
Anacystis marginata, Meneg. Nost. 98, t, 13, f. 1, Rabh. Alg.
Eur. ii., 52.
In ditches, free swimming.
Plate L X X X V I , fig. 6. Families magnified 400 diam.
Genus 85. CBATHROCYSTIS. Henfrey. (1856.)
Frond, a microscopic gelatinous body, at first solid, then
saccate, ultimately clathrate (fragments of the broken fronds
occurring in irregularly lobed forms) composed of a colourless
matrix, in which are imbedded innumerable minute cells, which
multiply by division within the frond as it increases in size.—
Quart. Journ. Micr. Sci., 1856, p. 53.
C lathr ccystis ærugincsa. Benf. Micr. Journ. 1856, p. 53. t. 4
/. 28-36. ’
Fronds floating in vast strata on freshwater pools, forming a
bright green scum, presenting to the naked eye a finely granular
appearance ; when dried, appearing like a crust of verdigris ■
cells minute. ’
S iz e . Fronds -03--13 mm. ; cells •0025--0085 mm.
Rabh. Alg. Eur. ii., 54. Kirch. Alg. Schles. 254.
Microcystis oeruginosa, Kutz. Tab. i., t. 8.
Polycystis oeruginosa, Kutz. Spec. 210.
Cn fresh water lakes.
“ The smallest fronds met with are usually roundish or ellipsoidal
When quite young they appear to be solid, butas they grow by the multil
plication of the internal cells and the secretion of gelatinous matter, the
expansion takes pla,oe chiefly near the periphery, so that the frond becomes
a hollow body. The walls of the sac then give way, aud, as the expansion
proceeds, orifices are formed in different parts, until the whole
becomes a coarsely latticed sac or clumsy net of irregularly lobed form.
Then this becomes broken up into irregular fragments of all shapes and
sizes (giving the stratum a granular appearance to the naked eye), each
of which recommences the expanding growth, and beooines a latticed
frond. The internal cells are very minute, but have a distinot margin
with internal granules. They multiply by dividing into two and four.
The gelatinous frond always presents a transparent border or peripheral
stratum, destitute of green cells ; but no boundary membrane exists, the
surface exhibiting a softened or half-dissolved aspect. On the approach of
winter the fronds ceased to increase, and by degrees most of the gelatinous
masses faded to a light brownish tint, swelled up and settled to the
bottom of the water in light floooulent clouds. They appear to beoome
half-dissolved, and to allow the green cells to beoome free, as many of the
latter were found free, adhering to the sides of the vessel. Perhaps these
reproduce the fronds in the next season. No zoospores were ever detected.”—
Henfrey.
Clathrocystis rosen-persicina, Oohn., is already included in this work, as
Pleurococcus roseo-fcrdciiius, pi. 2, fig. 6.
Plate L X X X V I . fig. 7. a, Thalli magnified 200 diam. ; 6, cells mag-
nified áOO diam.
Genus 86. COE LO S PHÆ R IÎJM . Xäg. (1849.)
Thallus globose, small, vesicular, hollow, composed of small
cells, which are associated in families at the periphery, immersed
in a mucous stratum, formed from the speedily confluent
teguments. Increase by division of the cells in all directions.
C oe lo sp hæ rium K n t z in g i a n u m . Nag. Einz. Alg. p. 54, t. 1 c.
Families sphærical. Cells snbglobose, geminate, or quaternate,
loosely disposed ; cell-contents blue-green, delicately
granulose.
S iz e . Cells •002--005 mm. ; families -06 mm. and more.
Rabh. Alg. Eur. ii., 55. Quart. Jonrn. Micr. Soi. 1869, p.
197. Kirch. Alg. Sohles. 254.
In ponds, meres, &c.
Plate LX X X V II. fig. 1. Families magnified 400 diam.
Genus 87. G OM PH O S PH OE R IA . KuU. (1836.)
Cells wedge-shaped, peripherical, 2-4-8 associated in radiating
families nestling in jelly, covered with a tegument, and forming
a solid globose free-swimming thallus. Cells dividing alternately
in three directions.
G om p h o sp hæ ria a p o n in a . Kutz. Tab. i., t. 31,/. 8.
Thallus microscopical, blue-green, often becoming pale, tegument
colourless, ra ther thick aud somewhat lamellose, central
cells smaller, cell-contents verdigris or pale blue-green,