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Reproduction takes place by means of asexual zoogonidia, and sexually
produced oospores. The latter do not at onoe produce new plants,
bnt several zoospores. The zoospores, which are developed in the early
part of the year from resting-spores of the previous year, produce only
asexual plants which only form zoogonidia. After a series of asexuri
générations, of variable length, a sexual generation arises, which according
to the species is monoBoious or dioeoious. Fertilization produces
one oospore in the oogonium, which developes iuto a reproductive body,
from the cells of which zoospores proceed in the next period of vegetation.
Zoogonidia may originate in all the vegetative cells of the Coleo-
chæteæ, and are always formed from the entire contents of the mothercell,
escaping through a round hole in the cell wall. t - .r,
“ In C. pulvinata the terminal cell of a branch swells up, and at the
same time elongates into a narrow sac, which then opens, and exudes a
colourless mucilage. The protoplasm of the swollen part, which contains
chlorophyll, forms the oospore, in which a nucleus is visible. Ihe
antheridia are formed at the same time in adjoining cells, two or bh^ree
protuberances growing out, which become separated by septa ; each ot
the cells thus formed, which have somewhat the shape of a fiask, is an
antheridium ; its entire contents form an antherozoid of oval shape
with 2 cilia, which is endowed with motion like a zoogonidium ; its
entrance into the oogonium has not yet been observed. The effect of a
fertilization is seen in that the contents of the carpogomum become
surrounded with a proper membrane and form the oospore.”
Coleochæte so lu ta . Frings. Jahrh. t. 1 ,/. 2,
Threads radiating from a common centre, furcately branched,
of equal length, closely packed side by side, prostrate, bnt not
connate, forming an orbicular disc. Cells one and a-half to
three times as long as broad, oogonia placed before the terminal
cells, globose, corticate.
S i z e . Cells -0 2 5 m m .
Eabh. Alg. Enr. iii., 389. Kirch. Alg. Schles. p. 50.
Attached to aquatic plants.
Plate L X X V I I I. Jig. 3. Plant of Coleochæte soluta, X 400. a, Oogonium
X 250 cliam.
Co leo chæte s c u t a t a . Breb. Ann. Sci. Nat., 1844, p. 29, t. 2.
Filaments and their branches radiating from, the centre, yery
densely connate in one stratum, forming a kind of parenchymatous
orbicular disc ; cells quadrangular, nearly equal or twice
as long, oogonia subglobose, peripherical, corticate above, naked
below.
S iz e . Cells -02--022 mm.
Eabh. A lg . E u r. iii., 390. Hass. Alg. 217, t . 77, f. 6.
Prings. Jahrb. t . i., f. 4 ; t iii., f. 3, 4.
Phyllactidium setigerum, Kutz. Tab. Phyc. iv.
On aquatic plants.
Plate L X X IX Coleochæte scutata. «, plant X 200. d, portion with
oogonia. c, portion with antheridia cells, d, zoospore, active and at
rest, e, development of young plants.
o hæ to ph o r a c bæ . 197
Coleochaete o rh ic u la iis . Brings. Jahrb. t. 1, /. 5.
Disc orbicular, parenchymatous, formed from one stratum of
■cells, brig h t green, cells oblong-quadrangular _ when old, by
pressure becoming often polygonal, usually twice as long as
broad. Oogonia oval, peripherical, mostly naked.
S i z e . Cells •012-'017 mm.
Eabh. Alg. Enr. iii., 390. Kirch. Alg. Schles. p. 50.
Phyllac tidium jmlchellum, Kutz. Tab. Phyc. iv.
On aquatic plants.
Plate LX X X . Jig. 1. a, plant X 200. h, portion with oogonia, after
Pringsheim X 250.
Genus 73. A rH A K O C H JE T E . Braun. (1847.)
Articulate threads prostrate, somewhat creeping, sometimes
more or less united in an irregular stratum. Branches decumbent
or ascending, cells bearing on their apex or hack, often a
long bristle which has no sheath at the base. Propagation by
zoogonidia. Oogonia a t present unknown.
A p h a n o c h ie te le p e n s . Braun Ilejuv. p . 184.
Filaments and branches procumbent, adprcssed ; cells slightly
swollen, of equal diameter in both directions, supporting an
indistinctly articulated bristle.
S i z e . Cells -005 -01 mm.
Kabh. Alg. Eur. iii., 891. Kirch. Alg. Schles. p. 71.
On Cladophora flavescens, and other Alga;.
Plate LXXX. fig. 3. Plant of Aphanochmte repens X 400.
A p h a n o c h s e t e h y s t i i x . (Thw) Eabh. Alg. Bur. ill. 391.
Filaments and their branches radiating, procumbent, ad-
pressed ; more or less connate, in a pale green irregular discoid
thallus. Cells somewhat cylindrical, produced at the apex into
a long bristle, which is not articulated.
S i z e . Cells ’01 mm. diam.
Oclilochaete hystrix, Thwaites in Harv. Phyc. B n tt. t. 226.
On aquatic plants in brackish ditches.
Perhaps scarcely deserving a place here, as it is almost, if not quite,
a iTiarine species.
Plate LXXX. f g . 2. a, plant of ApJtanocJmte hysirix, slightly
magnified, b, portion more highly magnified, after Harvey.
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