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Fam. I. Chlorotheciaceae, 
Plant-body unicellular and uninucleate. Cells either solitary 
and attached by a basal stalk, or united by mucilage to one another to 
form a small colony. Reproduction by sivanners which either ger¬ 
minate singly or conjugate in pairs (facultative gametes). The 
swarmers have one long conspicuous flagellum , and presumably a 
second short one (not yet demonstrated for any of the genera); and 
usually one lateral chromatophore (two in Mischococcus). 
Genera. 
:;: Cells solitary and attached by a thick or thin stalk. Vegetative 
division does not occur. 
1. Peromelia. Gobi, 1887. 
Cells rounded or pyriform, with a single chromatophore; 
quite imbedded in the mucilaginous investment of 
other Algae and attached to the host by a long stalk 
of extreme fineness. Reproduction by pyriform 
zoospores which burrow into the mucilage anew and 
attach themselves by the long flagellum which then 
becomes the stalk. Gametes not known. A piano- 
spores occur. 
2. Stipitococcus. West & G. S. West, 1901. 
Chiefly distinguished from Peroniella by its much smaller 
size : should, perhaps, be united with it as a recently 
described species is not so small. 
3. Characiopsis. Borzi, 1895. 
Cells obovate or round, with several chromatophores ; 
epiphytic by a short thick stalk. Reproduction by 
division of the cell-contents, either directly to eight 
zoospores (liberated by solution of the upper part of 
the mother cell-wall) or to a large number of spherical 
aplanospores which when liberated, become at once 
gametangia, each producing two to four gametes. 
Zygote germinates to form zoospores. 
4. Chlorothecium. Borzi, 1885. 
Cells obovate containing one or a few chromatophores, but 
otherwise resembling the previous genus. In repro¬ 
duction the cell-contents divide into a large number of 
spherical aplanospores (liberated by solution of the 
middle part of the mother-cell-wall) which at once 
become zoosporangia liberating two to four swarmers 
which are facultative gametes. Zygote germinates 
to form zoospores. 
[It seems highly probable that the vegetative cell of Chlorothecium 
will be able to give rise to zoospores directly (at all events under 
certain conditions). If this is so, then the life-histories as well as the 
morphology of the two previous genera become so similar that no clear 
generic distinction remains between them. Borzi calls the liberated 
clusters of aplanospores palmelloid states , but apparently these never 
grow or multiply independently.] 
