84
f
The following is a tabular arrangement of the British species :—■
Sec. 1. Cells not replicate at the ends.
A. Chlorophyll bands numerous (rarely two).
* Spores ovoid or elliptic.
t Membrane smooth.
1. crassa, Ktz.
2. jngalis, Dill.
3. nitida, Lk.
f t Membrane punctate.
None.
** Spores orbicular.
t Membrane smooth.
4. orthospira, Nag.
f t Membrane punctate.
5. orbicularis, Hass.
6. bellis, Hass.
B. Chlorophyll bands single or double (rarely ternate).
* Spore membrane smooth.
7. porticalis, Yauoh.
var. a. quinina.
Chlorophyll bands usually single.
var. fi. decimina.
Chlorophyll bands usually binate, rarely ternate.
var. s. rim laris, Hass.
Chlorophyll bands usually three.
** Spore membrane punctate.
None.
N.B.—Spirogyra elongata. Berk. Glean., p. 33, tab. 12, f. 3 (Eabh.
Alg. iii. 241), would follow here but that the fruit is unknown, and heuoe
it is uncertain.
C. Chlorophyll bands single.
* Spore membrane smooth.
9. condensata, Vauch.
9. longata, Vauch.
10. flavesoens, Cleve.
** Spore membrane punctate.
(N.B.—No record of Sp. velata or Sp. punctata in Britain.)
Sec. 2. Cells replicate at the ends.
A. Chlorophyll bands usually two or more.
* Spore membrane smooth.
11. Sp. insignis, Hass.
** Spore membrane punctate.
12. Sp. calospora, Cleve.
B. Chlorophyll bands single.
* Spore membrane smooth.
13. Sp. quadrata, Petit.
14. Sp. Weberi, Katz.
15. Sp. tenuissima, Hass.
** Spore membrane punctate.
None.
The English student may also consult with advantage a memoir “ on
the germination of the resting spores in Spirogyra,” by Dr. Pringsheim,
translated in the Annals of Natural History, 2nd ser.. Vol. xi. (1853),
p. 210. “ On the Structure and Division of the Vegetable Cell,” by J.
M. Maofarlane, in Transactions of the Botanical Society of Edinburgh,
Vol. xiv. (1881). Pringsheim’s Eesearches on Chlorophyll, translated by
Professor Bayley Balfour, in Quarterly Journal of Microscopical
Science, Vol. xxii., new series (1882). Darwin “ On the Action of Car.
bonate of Ammonia on Chlorophyll Bodies,” in Journal of the Linnean
Society, Vol. xix. (1882).
S e c t io n 1 . C e l ls n o t r e p l i c a t e a t t h e e n d s .
A. Chlorophyll bands numerous {rarely two).
Spizogyxa cx a ssa . Kutz.
Sterile cells with the extremities truncate, equal or twice as
long as broad. Chlorophyll hands four or more, making i - 1 ^
turns.
Zygospores broadly and obtusely oval, membrane even.
Sporiferous cells persistent, not swollen.
S i z e . Cells • 1 2 - - 1 5 m m . d iam . (Rabh.), '1 5 m m . d iam .
{Petit), zygospore • 1 4 - '1 5 d iam . {Petit), ’1 3 X '1 2 ; ’1 4 x '1 2 ;
•1 6 X -1 2 m m . {M.C.G.).
Zygnema serratum, Hass. Alg. t. 18, f. 1.
Spirogyra crassa, Kutz. Tab. v. t . 28, f. 2 ; Kutz. Phy. Gen.
t . 14, f. 4 ; Kirsch. Alg. Schl. p. 1 1 9 ; P e tit Spirogyra p. 32,
t . 12, f. 3, 4 .
Spirogyra Heeriana, Kutz. Tab. v. t. 28, f. 3.
In ponds, &c. Fruiting in summer.
Hassall says of his Z. serratttm that the “ filaments are of nearly the
same diameter as those of Z. orbie^ilare, but less mucous, from which
species it may readily be distiugnished by the fewer number and serrated
appearance of the spores, the larger size of the granules, and the
form of the sporangia, which in Z. orhiculare are nearly sphærioal, and
compressed, while in Z. serratum they are broadly ovate.”
The sterile cells have a greater diameter than any other British
species, whilst their length varies from about balf a diameter to two
diameters. The zygospore is comparatively broader than in S. jugalis,
and slightly flattened, so that when seen in certain positions it appears
to be narrower than it is, and more resembling that of S. jugalis.
On plate 32, figs. 1 and 2, the nucleus is represented in the centre of
the cells. Pringsheim has recently remarked, as a fact hitherto unrecognised,
that “ the threads of the protoplasm extending ontwards from
the central plasma mass in each cell, do not, as was supposed, end iu the
general protoplasmic lining of the cell wall, bnt each passes directly or
by its branches to the internal surface of a chlorophyll band, and there
dilates in a trumpet-like manner, and grasps, as it were, an amylum
body.”—Researches on Chlorophyll, p. 81.
Plate X X X II . fig. 1. o, sterile cells X 200 ; 5, fertile cells with
zygospores X 200 ; c, fertile cells of Rhynehonema form with zygospore
X 200 ; d, outline of zygospore X 400.
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