A very common parasite on Cystoseira fibrosa, whose branches
are rarely found free from the olive-coloured soft pencils of this
little plant. In size and appearance to the naked eye there is
much resemblance to Elachistea fucicola (Tab. CCXL.), except
that the colour is generally greener, and the length of the
tufts rather less; but under the microscope these species are
very readily known from one another. E. flaecida is remarkable
for the shortness of its articulations, in proportion to their
breadth throughout the lower and middle portions of the filaments,
and for the gradually increasing length of the cells towards
the apices. The filaments, also, taper exceedingly at the base;
and the tubercle from which they originate is of very much
smaller size than in E. fucicola.
Fig. 1. Tufts of E lachistea flaccida growing on ^
Vertical section of part of a frond, showing a portion of the tubercle, with
paranemata and spores, and part of two filaments. 3. Apex of a filament.
4. Spore, with its paranemata -.— all magnified.