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I t forms large masses on the water, fall of air-biibbles, being pale
and yellowish above, and of a blackish green beneath. Filaments not
lubricous, nearly equalling tbose of Spii'ogp'a nitida, but with much
longer articulations. When yonng the coiour is of a dull pale green,
and about three imperfectly spiral lines of shining granules are with
difficulty distinguishable. Afterwards these lines become more con-
spionous, the rest of the filament being now perfectly colourless, and
their component granules larger, but their arrangement is still irregular.
The filaments subsequently unite here and there, not by every articulation,
and their connecting processes are usually nearer to one end of the
vessicle than to the other. Such filaments are divaricated at the points
of connection. In some of the combined articulations the contents
appear unchanged, in others they form a mass of larger granules than
in the lines, and some have a large oval sporidium which often swells
the joint. Some traces of unchanged lines occur, now and then, in the
fructifying —English Botany, 2nd ed., p. 176.
a, sterile cells X 200; b, c, d, e, coningatino- cells
X 200 ; / , zygospore X iOO. After De Bary.
G en u s 47. ZYGOGONIUM;. Kutz. (1843.)
Cells cylindncal or barrel-shaped, with a compact, often many-
layered glittering cell-wall. On each side near the middle an
irregular chlorophyll-body, each furnished with a starch granule,
both often confluent in an axile string (in the very thick-wailed
cells usually concealed by granules). Connection of the copulating
threads ladder-Iike. The protuberances of the two contiguous
inter-growing threads th at receive the chlorophyll-
contents are bounded by partitions into fruotifying-oells, which
then coalesce into a not-contracted zygospore.
Z y g o g o n ium e iic e to ium . De Bary Conj. p. 79.
Sterile cells, to 2 times as long as broad.
Zygospores subglobose or oblong, sporoderm rather thick
even. ’
S i z e .— Cells -013 t o -018 mm. diam. Zygospore -013 x '025
mm.
var. a. tezzestiris,
Zygogonium ericetorum, Kntz. Tab. v. t. 10, Dickie Bot. Guide
M6. Jenner FI. Tunb. Wells, 184. Hass. Alg. 174, t. 41,’
I. 3, 2. ’
Zygogonium torulosum, Kutz. Tab. v. t. 14.
Gonfmwa ericetorum, Eng. FI. v. 850 ; Harv. Man. 125:
Dillw. Conf. 1 .1, Eng. Bot. 1st Ed., t. 1553, 2nd ed. t. 2473
? 9 r ' D Hrev. Crypt. FI. t. 261 (?) Mack. Hib.
224. FI. Devon, ii. o l. Hook. FI. Scot. ii. 81
Conferva alpina, Eng. FI. v. 350. Harv. Man. 125. Grev
Sc. Crypt. FI. t. 2 6 1, f. 2.
On heaths.
ZYGNEMACEÆ. 99
var. b, A q u a ticum .
Zygogonium didymum, Eabh. Hedw. 1, t. 3, f. 2.
Zygogonium Agardhii, Rabh. Alg. Enr. iii., p. 253.
Conferva purpurascens, Carm. Eng. FI. v. 350. Harv. Man
123. Mack. Hib. 224.
In pools, bogs, &c.
This is a very polymorphous species, some of the forms being terrestrial,
and always sterile, others are aquatic producing zygospores. The
old name ai Zygogonium erictorum has been retained, but undoubtedly
all these various forms belong to Zygogonium Agardhii, Kabh. {Zyg.
didymum, E.)
“ The colour, no less than the condition of the endochrome, varies
considerably in this species. In some specimens tbe filaments are of a
bright green, iu which case tbey have always been found immersed in
water ; while in others, and more frequently, they are purple, of which
colour they invariably are when found spreading over swampy heaths."
—Hass.
Plate X L . fig. 2. Terrestrial form, a, sterile cells X 400 Fig. 3.
var. aquaticum. a, sterile cells X 400; b, o, oonjugating cells with
zygospores X 400.
Doubtful Species.
Zygogonium grac ile . Berk.
' Sterile cells about five times as long as broad, of a pale or
yellowish green colour.
Zygospore unknown.
S i z e . Cells -Oll.-'Olfi mm. diam.
Rabh. Alg. Eur. iii., 255.
Zygnema gracile, Berk. Glean, t. 12, f. 3.
Face of a dripping rook.
Eabenhorst includes this with uncertain species of Zygogonium, but it
seems more probable that it is a Zygnema, and perhaps one of the
varieties of Z. Yaucherii. The following is the original description :—
^ “ Pale dirty yellowish green, mucous ; threads extremely fine, articulations
not at all constant in length, 4 to 8 times as long as broad, marked
in the centre with two approximate roundish globules. Slender filaments
occur in tbe same mass, with joints longer in proportion, the
green mass not divided into two distinot portions. I have not seen it
conjugated.”—Berkeley.
Plate XL. jig. 4. Sterile cells X 400.
G en u s 48. IHOUGEOTIA. DeBary. (1858.)
Cells with axile chlorophyll-plates. Copulation ladder-like.
Zygospore drawn together in the swollen, bladdery, persisting
middle space.
De Bary includes this genns iu Zyynemeoe, although Wittrock joins it
with Mesocarpus, and it seems to us very difficult to indicate any trne
generic distinction apart from the dividing off from the parent cells of
the empty persistent cells which remain some time attached to the zygo-
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