Fritsch, Obseryations on the young plants of Stigeoclonium Kütz, 373 
very readily with methylene blue, taking on very much the same 
colour as the cell-walls.. In the stained condition it showed no 
special structure, although its outer edge was generally somewhat 
frayed in appearance'); its continuity was frequently slightly inter- 
rupted opposite the transverse walls of the filament. The cell-walls 
of the filaments themselves were quite distinet and apparently un- 
altered; no mucilage was formed between the successive cells, their 
transverse partitions remaining quite thin. Owing to this the fila- 
ments retained their original appearance with the exception that 
the cells were rather more barrel-shaped than usual in this species. 
Schröder, who has recently published an excellent treatise 
on the mucilaginous structures, oceurring in Algae, in the case of 
: Stigeoclonium (Schröder 02, p. 145) refers to Cienkowski’s work 
(ep. Cienkowski 76P), in which the following passage occurs (p. 
539): ,„|Die Wände können dick mehrschichtig sein, dann sind die 
Lumina der Zellen sphäroidalisch, von einander durch mächtige 
Schichtenbildung entfernt (Fig. 13)], oder die Wände bleiben dünn, 
und die fest an einander schliessenden Glieder behalten ihre cylin- 
drische Form. In beiden Fällen kann eine breite, sämmtliche Glieder 
umhüllende Gallertschicht erscheinen ...... “ This description 
agrees well with the phenomena observed in Sig. variable. Such a 
strong development of mucilage was only observed in this species. 
In Stig. nanum the creeping, basal portion was often better 
developed (Tab. XI, fig. 25; Tab. XII, fig. 26, 27, 28). The cells of 
‘ tkis part of the young plant are in this species often considerably 
swollen, as compared with those of the upright branches; this is 
particularly evident in Figs. 25 and 27. These cells have a parietal 
chloroplast, which is connected at different points by strands passing 
right across the cavity of the cell; a considerable portion of the 
cell-cavity thus remains quite colourless. "The cells of the uprieht 
filaments have a similar parietal layer with usually a little bridge 
of chlorophyll across the middle. In each cell one or more usually 
two pyrenoids are to be found. Vertical branches are very abundant 
in this species, almost each cell of the base, developing one (Fig. 
25, 27); these upright filaments, as already mentioned, frequently 
branch very early, as shown in Fig. 26 (at a) and in Fig. 29. The 
base itself is usually but slightly branched. 
Many of the plants of Stig. nanum from the pond at Kew, 
were observed to originate from amongst a group of protococcoid 
cells (Tab. XII, figs. 28, 29), which undoubtedly constituted one of 
the forms in the life-history of this species?). "There was no trace 
of mucilage around these cells. Cienkowski (76®, p. 546) showed 
that in Stigeoclonium the individual cells of a filament often become 
free by the loosening of the contact between them, and that these 
cells further divide in: various directions to form palmelloid or proto- 
coccoid groups. In his own words we meet with „alle möglichen 
Übergänge von einer starken Gallertbildung zu einem kaum merk- 
1) The neilklline blue did not appear to causelany shrinkage of the 
mucilage, as Schröder so frequently observed it. 
2) cp. also Kützing (43. p. 253), where he remurks of the delicate 
Stig. stellare: „Seiner Entstehung geht immer die Bildung von ERRETESTE" 
artigen Kügelchen voraus“; see his Tab. 9, fig. 
