Environmental Engineering Reference
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has two equal-length flagella which can
point in different directions from the colony
edge . .........................
Eudorina
Unlike the cells of a
Pandorina
colony, those
of
Eudorina
are spherical and spaced out
within the mucilaginous matrix near to the
edge, leaving a clear zone at the centre. In
immature colonies, they may be more closely
packed. The chloroplasts are cup-shaped and
greenwithoneormorepyrenoidsandaneye-
spot. The storage product is starch. Widely
distributed in the plankton and can form
dense growths. Can impart both taste and
odours to drinking waters (Palmer, 1962).
Chlorophyta. Plate X. Fig. 4.39.
20 μm
75
(73) (a) Chloroplasts golden-brown. Cells pear-
shaped with thread-like mucilage strands
connecting them to the colony centre. Stor-
age product leucosin . ...........
Uroglena
Colonies of
Uroglena
can be quite large,
up to 1 mm diameter, and are composed of
many hundreds of cells. Individual cells (10-
22 μm in length) possess one or two chloro-
plasts and have two, unequal-length, flagella.
Cysts are produced which have smooth walls
and may not have a collar. Although similar,
Uroglena
colonies can be distinguished from
Volvox
by their golden-brown chloroplasts,
pear-shaped cells and the unequal flagella.
Commonintheplankton.Reportedtobeable
toimpartunwantedodourstodrinkingwaters
(Palmer, 1962). Chrysophyta. Plate X.
25 μm
Figure 4.39
Eudorina
. Top: Cells dispersed (not
touching) within the globular colony. Bottom: Colony
slightly compressed to show central cavity and mucilagi-
nous matrix. Indian ink preparation. The flagella are not
visible in either the DIC (top) or BF (bottom) images.
(b) Chloroplasts green, storage product
starch. Cells spherical with interconnecting
mucilaginous strands and are situated around
the periphery of the colony. Mucilaginous
strands do not radiate from the centre of the
colony. Each cell with two equal-length flag-
ella..............................
Volvox
duction occurs by formation of daughter
colonies that develop from special cells
within the hollow colony, from which they
are released. Sexual reproduction is ooga-
mous, with the formation of sperm packets
and egg cells from vegetative cells, leading
to zygote formation. Common in the plank-
ton. May produce a fishy odour in drinking
waters (Palmer, 1962). Chlorophyta. Plate X.
Fig. 4.40.
Volvox
colonies are large (up to 2.5 mm
diameter) and spherical, composed of hun-
dreds or thousands of cells. Asexual repro-
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