(I*
. Kl
i
fill
cell, and as if on a common stipes, that is, as if all were ‘ in ramulis
—qnaternatim conjunctse.’ ” The larger lower cells are combined,
inter se, by a soft irregular colourless furcated (almost as if
shrivelled) stalk, into a crowded colony or family. This branched cluster
of cells requires to be broken up and pressed out ere the arrangement
referred to can be seen. The structure and mode of arrangement of the
cells (which are bright green, with a pale narrow little space at the
upper extremity, and with large chlorophyll granules) becomes thus of
somewhat complex appearance, nor did it appear to have been made out
fully by Braun himself, as conveyed by his description.—See Quart.
Journ. Micr. Science, 1872, pp. 195, 198.
Genus 21. KIISCHOCOCCUS. iVa^r. (1849.)
Thallus dichotomously branched, bearing the terminal cells.
Cells globose, terminal, gemmate or, quaternate. Division of
cells in one direction. Propagation by zoogonidia.
This genus is confined a t present to a single species.
n iischococcus co n feiv ico la. Niiff. Einz. Alg. p. 82.
Cells globose, even, geminate, ternate or quaternate, on the
tips of the branches, bright green, delicately granular, destitute
of a chlorophyllose vesicle ; stem hyaline, spuriously articulated,
often swollen at the angles.
S iz e . Cells -0045--000 mm. (Babh.).
Eabh. Alg. iii. p. 54, fig. 29.
Attached to filamentous Algas in ditches, near Stafford,
August, 1849 (Eev. E . C. Douglas).
This interesting little plant is liable to be overlooked on acoonnt of its
small size and the delicate hyaline stem, only the pair, or more, of little
globose green cells being at first visible.
Plate X I. Jig. 4. a, two plants parasitic on Conferva; h, youiig
plants J c, terminal branches with 4 cells ; d, swollen joints of stem j e,
free cells. All magnified 400 diam.
.
: |f-
F amily II. PROTOOOCOAOBÆ.
Unicellular algæ, in the strictest sense, chlorophyllous, without
terminal growth, or ramification, without a vegetative
generation of cells. Either single, segregate, or associated in
families. Cells of the families either indefinitely increasing in
number (then forming families') or of a definite number (then
forming a cænobium).
Propagation by means of gonidia, arising in the mother cell
by free cell formation ; gonidia of two kinds, the one larger,
maci'ogonidia, the other smaller, microgonidia ; the former
oblong, mostly produced anteriorly into a pale bi-oiliate beak,
rounded and greenish at the posterior end, developing into an
individual plant ; the microgonidia similar to these, and also
motile, but passing after a short time into a quiescent state, and
a t last into resting spores, or hypnospores.
This family is usually subdivided iuto the following subfamilies
: —
1. P rotocooceæ.
2. C hlorocoooaobæ.
3. POLYBDRIEÆ.
4. S o e n k d e sm eæ :.
5. H y d e o d ic t y b æ .
6 . ÜPHIOOYTIEÆ.
7. P e d i a s t r b æ .
8 . S o r a s t r e æ .
9. CHARACIBiE.
Many of these small sab-families include but a single genus, so that,
in effect, the character of the sub-family is that of the genus ; heuoe
they are of little value, especially in a local flora.
8ub-Family 1. P e o t o c o c c e j i ) .
Cells spheroid, segregate ; cytioderm thin, hyaline, without
integument, swimming free, or, when not growing in water,
forming a thin pulverulent stratum. Contents in the beginning
homogenous, then granular, green, or reddish.
Only one genus has yet found a place in this sub-family, of which
one species is British.
G e n u s 22. PEOTOCOCCUS. Ag. (1824.)
Characters the same as in the sub-family. Propagation by
mobile gonidia.
Fzotococcua v iiid is . Ag. Rabh. Alg. in ., 56.
Cells small, segregate, aoounmlated in a broadly expanded
stratum, of a yellowish green colour, either pulverulent, or,
during moist weather and after rain, somewhat gelatinous.
S iz e . Cells -0025--004 mm.
On the trunks of trees, fallen branches, and damp walls
throughout the year.
I t is very probable that this is only a condition of Pleurococcus vulgaris
Fiate X II. jig. 1. Cells magnified 400 diameters.