Fritsch, Observations on the young plants of Stigeoclonium Kütz. 377 
irregular shape (Tab. XI, fig. 1). It then either grows out to form 
an unbranched filament (fig. 2) or it commences to branch almost 
at once (figs. 3, 4). Ultimately we always obtain a well-branched, 
more or less radiate, discoid base, as shown im fig. 5. At this 
stage, at which the base consists of between ten and twenty cells, 
vertical branches have not yet originated. Fig. 6 shows a young 
branch at h, which has arisen from one of the cells of the basal 
portion and is as yet only two-celled; its elongated, narrow cells 
contain only absolutely colourless protoplasm, (indicated by shading 
in the figure). Young plants with more fully -developed upright 
branches are shown in figs. 8 and 9. The cells of these branches 
are elongated and very narrow, and the transverse walls separating 
them are only seen on careful observation; the broad plugs of proto- 
plasm (shaded), which constitute the colourless contents of each cell, 
are far more likely to be taken for transverse partitions in a cur- 
sory examination. These colourless branches can only be compared 
to the hairs found in this and other species of Stigeoclonium, SO 
that here we have a creeping basal portion, which can produce 
hairs alone in lieu of upright branches; the resemblance to Aphano- 
chaete is very great. (cp. West & West 02, Pl. 17, Fig. 11)t). 
Normally, however, in the species under discussion the upright 
branches have a different appearance, consisting of typical chloro- 
phyll-containing cells below, which apically pass over into the colour- 
less, much elongated cells of the hair (Figs. 11 and 14); these latter 
have quite lost their contents. The hairs themselves end bluntly. 
Finally the fact, that the upright branches, although often of con- 
siderable length, are absolutely unbranched, is of great impor- 
tance. 
The ‚fact, that in epiphytic species of Stigeoclonium with a 
strongly -developed basal portion only hairs may be developed in 
place of vertical branches, has before now been remarked upon by 
Huber (92%, p. 323), according to whom „il n’est pas rare que, 
dans les premiers stades du developpement des formes epiphytes du 
genre Stigeoclonium, chez lesquelles le thalle rampant est tres deve- 
loppe, celui-ci fournisse (quelquefois a cöte de rameaux dresses ordi- 
naires) des rameaux dresses entierement transformes en poils pluri- 
cellulaires. La cellule basilaire de ces rameaux a encore conserve 
plus ou moins son caractere vegetatif, mais, des deux cellules qui 
resultent de ses divisions la superieure se transforme constamment 
en cellule de poil.‘“ Such young plants would, (especially if examined 
{rom dry or otherwise preserved material) in no respect?) differ from 
those species of Aphanochaete (or Herposteiron Näg.). which have 
been described as possessing distinctly septate hairs. It is m fact 
my opinion that these species are merely arrested stages in the de- 
velopment of epiphytic species of Stigeoclonium. W. West and G. S. 
West (02, p. 130) remark in connection with the ZHerposteiron 
crassisetum, vecently described by them, that .‚this species is cha- 
; !) Chodat (02, p. 301, Fig. 216) figures a plant of St. flagelliferum, 
which has a well-developed base, from which a few short upright branches 
have arisen, as well as a 6-celled elongated hair. 
?) Species of the genus Aphanochaete frequently form a base, resembling 
that shown in my figures. 
Beihefte Bot. Centralbl. Bd. XIII. 1903. 26 
