The Botany of Iceland - 01.12.1928, Blaðsíða 108

432
JOHS. BOYE PETERSEN
Fig. 36.
Chlorella rugosa n.sp.
From sample 326.
(X 1200).
ences between the
to different life-conditions.
contents of a cell along a somewhat oblique plane
of division, thence by division into 4 or 8 cells by
repeated bipartition. Whether the reproductive cells
thus formed develop into zoospores or aplanospores
I have not been able to ascertain from the dried
material at hand. The daughter cells are liberated
by the wall of the mother cell being dissolved at
one end. They have a somewhat different shape
from the full-grown cells, being more oblong or
fusiform.
There was some difference between the two
samples. In sample No. 349 (Fig. 35) the cells were
on the whole larger than in sample No. 326 (Fig. 36),
and the sporangia most frequently contained 8 spores
in contrast to sample 326 where thej' rarely con-
tained more than 4. However, I regard these differ-
two samples as a mere variation most probably due
Ulothricales.
Ulothricaceæ.
Ulothrix zonata Kötz. Chodat 1902, p. 267.
E. Icel. 55 c.
Can probably only grow in water or in places where there is plenty
of water. It was found at the entrance of a small rocky cave with
dripping water in company with Tribonema bombycinum and numerous
Diatoms (especially Meridion circulare). The filaments attained a dia-
meter of 22—35 /t.
Hormidium flaccidum (Kútz.) A. Br. A. Braun Rab. Algen No. 2480
(cited after Gay 1891, p. 79.
Ulothrix ilaccida Kfltzing 1849, p. 349.
E. Icel. 55 b, 88, 91 - N. Icel. 179, 217 - N. W. Icel. 268, 269 -
S. Icel. 294, 352, 387.
This species is noted for its unusually great power of adaptation
in regard to different substrata (Hansgirg 1887, p. 83, Wille 1912,
p. 449, Puymaly 1924, p. 223).
In Iceland I have found it on irrorated rocks, partly freety exposed
to the light, partlj^ in a small cave where it had formed numerous
resting aplanospores with spiny outer wall as described by Wille (1912,
p. 452, Tafl. 14, flg. 20) from a growth in a similar localhy in Norway.
It was not possible for me, liowever, to see the aplanospores lying within
the cells of the mother plant. There was plenty of water present in the
localities mentioned. I have, however, also found it in drier localities,
on moss-covered stones, on earth, on turf in thc wall of a house, on
walls.