139 
Hirshals, on stones near land, 1—2 m; off Højen, on pebbles within the first shoal and between the 
first and the second shoal. — Lf: XY, at Mullerne, Thisted Bredning, 6,5 m; XV, north of Ronnen at 
Lem Vig; Oddesund, 6,5 to 10 m or deeper. — Kn: South of Skagens Gren, 13—15 m (Kramp); fC, 3 
miles S.W. by S. of Skagen light-house, 15 m, denudate in October; YS?, 
north of Græsholm, Hirsholm, 15 m; YX, east of Nordostrev, Hirsholm, 
23—28 m; south of Hirsholm, 13 m; XH and XL, east of Marens Rev, 11,5 
—15 m. — Ke: FC, east of Flyndergrund, east of Læsø 17—18 m. 
7. Polysiphonia nigrescens (Engl. Bot.) Grey. 
Harvey in Hooker, Brit. Flora II, 1833, p. 332; Phyc. Brit. III, 1851, Plate 
277; J. Agardh, 1863, p. 1057; Kolderup Rosenvinge, 1884, p. 13 (Re- 
sume p. 2), plates I—II figs. 15—29; Hauck, Meeresalg. 1884, p. 2445 
Falkenberg, 1901, p. 129; Svedelius, Östersj. Hafsalg., 1901, p. 121; 
Kylin, 1907, p. 143; Lakowitz, Alg. Danz., 1907, p. 20; Kylin, 1923, 
p. 116; L. Batten, 1923, p. 306. 
Conferva nigrescens Smith, Engl. Bot. 1806 Plate 1717. 
Hutchinsia nigrescens Lyngb. Tent. 1819, p. 109 Tab. 33. 
Hutchinsia violacea Lyngb. Tent. 1819, p. 112 ex parte, tab. 35 A.1—2. B.2. 
f. pectinata J. Agardh, I. c., p. 1058; Aresch. Exsice. 
No. 63 and 57 (Polys. Brodici). 
f. fucoides J. Ag., 1. c. 
f. flaccida Aresch., 1850, p. 49; Kylin, 1907, p. 143, 
Taf. 5 Fig. 1. 
f. reducta Svedelius, 1901, p. 121. 
The morphology of this very common species has been 
described at length by me (1884) and later by FALKENBERG 
(1901). The trichoblasts are arranged in a spiral with rather Fig. 392. 
large angles of divergence, about ?/;. They may occupy all NR 
the consecutive joints, including those bearing branches which 3ı1st. Tip of shoot without 
may take the place of some of the trichoblasts in the spiral te EES KJOLE 
(comp. K. R. 1884 fig. 24). But it also happens that “sterile” 
joints occur between the trichoblast- or branch-bearing ones, e. g. that every second 
joint only bears a lateral organ, or the sterile joints may occur more sparsely and more 
irregularly. In other cases the shoots are entirely or almost entirely devoid of tricho- 
blasts; the branches are then placed in a spiral or they are biseriate, alternate, 
separated by a varying number of joints bearing no lateral organs. The latter occurs 
particularly in the f. pectinata J. Ag. but also in the other forms (fig. 392, comp. 
FALKENBERG, p. 129). The main branches often begin by bearing only branches, 
no trichoblasts. Endogenous branches normally arise at the base of the primary 
axis and of the main branches (fig. 396), and at the base of almost all later well 
developed branches, mostly at their inner face (fig. 393, K. R. 1884, figs. 25—28); these 
56* 
