396 
The spores when discharged are globular and naked’, but are soon surrounded 
with a thin membrane. The cell-wall was sometimes found thickened on one side, 
undoubtedly where the first rhizoid would later appear. The cell is then divided by 
an eccentric wall in a smaller cell which gives rise to the rhizoid, and a larger 
cell which divides by walls parallel to the first and gives rise to the primary axis. 
The rhizoid is separated from the small cell by a trans- 
versal wall. My pictures (fig. 289) agree with PRINGSHEIM’s 
figs. 7b, d which represent spores germinating within the 
membrane of the heap. 
The species is perennial and has been met with in 
all seasons. It attains a length of up to 8cm. In winter it 
Fig. 289. is generally smaller, some of the shoots being shed, but 
Plumaria elegans. Sporelings new shoots are produced from the remaining parts. The older 
from germinated paraspores. z = 
230 : 1. shoots are often overgrown with Membranipora. It grows 
partly on stones, partly on various Algæ, as f. inst. Fur- 
cellaria, Chondrus, Ahnfeltia, Fucus serratus, from low-water mark to 9 meters depth. 
When occurring near low-water mark it always grows in shadow f. inst. under 
Ascophyllum nodosum. The paraspores have been met with at all seasons except 
in spring, in the greatest quantity in summer. 
Localities. Kn: TV, Krageskovs Rev; Hirsholm, at various places (Hornemann 1815, !); Busse- 
rey, Brune Rev, Laurs Rey and Marens Rev by Frederikshavn; harbour of Frederikshayn; TL, west of 
Nordre Ronners light-house, 9—14 m. — Su: Gnetare Grund (Swedish coast, Boye Petersen). — Bm: 
SD, N.E. of Moen, 23,5 m, loose, with other loose Algæ, a small specimen with divaricate acuminate 
pinnules, sterile (see above). 
Ptilota C. Agardh. 
1. Ptilota plumosa (L.) Ag. 
C. Agardh, Synops. Alg. Scand. 1817, p. 39; Lyngbye 1819, p.38 Tab. 9A; Kützing, Phyc. gen. 1843, 
p. 378, Taf. 46; Harvey, Phyc. Brit. I, 1846, Pl. 80; Kützing, Tab. phyc. Vol. 12, 1862, Taf. 54; B. 
M. Davis, Developm. of the procarp and cystocarp in the genus Ptilota, Botan. Gazette Vol. 22, 
1896; Buffham 1896 p. 189; R. W. Phillips 1897, p. 362 Pl. 18 Figs. 16, 18; Kylin 1913, p. 58. 
Fucus plumosus Linné, Mantissa pl. alt. 1767, p. 134; Fl. Dan. Tab. 350, 1767. 
Pterota plumosa Cramer 1863 p. 25 Taf. III Figs. 4, 5, IV Figs. 1—7, V Figs. 1—5, VI Figs. 1—5. 
The development of the frond has been carefully described by CRAMER 
whose paper (1863) may here be referred to. Transversal and longitudinal sec- 
tions of a younger frond have been figured by KirzinG (1843, Plate 46). In both is 
shown a small-celled outer cortex and an inner layer composed of larger cells and 
surrounding the axile cell-row. In the longitudinal section it is rightly shown that the 
opposite pinnulæ only issue from every other joint, but the connection between the 
pinnulz and the axial cells of the long shoots is not represented. As shown in my 
* According to BurrHam (1893, p. 303) the paraspores are “possessing a cell wall even before 
discharge”. If this must be understood to mean that the spores are also provided with a cell wall 
when discharged, it is not in accordance with my observations. 
es 
