Fritsch, Observations on the young plants of Stigeoclonium Kütz. 375 
events in my cultures I never observed anything of the kind. It 
would seem therefore, as though in addition to the two types of 
development, described by Berthold (cp. p. 1, 2), a third occurs, in 
which by the germination of the zoospore an uprieht filament with 
a basal cell, specially modified for attachment, is formed. Possibly 
the Stig. amoenum, figured by Gay (91, Fig. 47c), belongs to this 
type, although the basal cell is scarcely modified. Nägeli’s (55, 
Tab. IH, figs. 18—22) figures of Stg. insigne are drawn from too 
early stages, as are also those of Thuret (50, Pl. 18, Fig. 15) for 
Stig. protensum Kütz, to be able to settle this point; in the latter 
species, however, a basal cell is figured by Kützing, as already 
mentioned. In St:g. nanum young plants of the type, shown in 
Tab. XI, fies. 22—21 were sometimes observed; in these the lowest 
eell of the young upright filaments entirely resembled the others, 
but at the point of its adhesion to the C/adophora, on which it 
was growing, a eranule of the red matter above mentioned was 
often present. I was not successful in following up the further 
fate of these young plants. 
In si. variabıle the basal cell often grows out into a number 
of rhizoids (Tab. XI, figs. 19, 21), which may ultimately become 
multiceillular and grow to a great length (Fig. 16). Such rhizoids 
also ar se from cells above the base (Tab. XI, fig. 19; Tab. XI, fig. 
32, R); they may grow out in all directions and are frequently 
- present in considerable number. Although in the young stage the 
cell-contents in these rhizoids resemble those in the main filaments 
(Tab. XII, fig. 32) they are later on either quite empty or the proxim- 
al cells may have a little contents; the distal ones are always 
quite empty, being usually longer and narrower than the former 
(cp. also Cienkowski 76#, p. 539, Tab. IX, fig. 8). In general 
appearance they are not unlike the branches terminating in hairs 
(ep. especially Tab. XII, fig. 32 R), but the longer ones usually possess 
an irregular, almost undulating outline (Tab. XII, fig. 30)') They 
should be considered as modified descending branches of the ordinary 
type. — Not infrequently the rhizoids are branched (Tab. XT, fig. 16), 
but mostly only near the base. The excessive formation of rhizoids 
in St. variabile in some cases (Fig. 16) may have been due to the 
existence of slightly abnormal conditions. In the other species with 
a well-developed basal portion such rhizoids were only rarely ob- 
served (cp. fig. 7 for Stig. farctum; figs. 28 and 29 for Stig. nanum, 
where they are however quite short). 
Berthold (78, p. 201) remarks that such rhizoids are rarely 
met with in nature; this is also my experience, those, just described 
in St. varıabıle, appearing only after the Alga had been kept indoors 
for several weeks. Gay (91, p. 42, 43), however, found that they 
were always present in St. amoenum and St. nanum. His description 
of the rhizoids quite coincides with that, I have just given; he 
says: „on peut les considerer morphologiquement comme des ra- 
meaux adaptes a une nouvelle fonction........ Ds sont simples 
(fig. 51a) ou peuvrement ramifies (fig. 52a, b). Is different des 
rameaux vegsetatifs; plus gräles, ils s’attenuent peu & peu vers leur 
2) cp. also Chodat (02, p. 321, Fig. 235). 
