6. Polysiphonia atrorubescens (Dillw.) Grey. 
Greville, Flora Edinensis, 1824, p. 308; Harvey, Phye. Brit. Vol. 2, 1849, pl. 172; Kützing, Tab. phye. 
13. Band, 1863, Taf. 82; J. Agardh, 1863, p. 1035; Farlow, Mar. Alg. N. Engl. 1881, p. 174; Kuckuck, 
Bemerk. I, 1894. Wiss. Meeresuntersuch. N. Folge I. Bd., p. 253, Fig. 21; L. Batten, 1923 p. 289 
fig. 26—29. 
Conferva atrorubescens Dillwyn, Brit. Conf. 1809, pl. 70. 
Polysiphonia Agardhiana Greville, Scottish Cryptog. Flora Vol. IV, 1826, plate 210; Kiitzing Tab. phye. 
13. Band, 1863, Taf. 49. 
A number of vigorous endogenous creeping shoots are given off from the base 
of the primary shoot and from the long branches issuing from its base (fig. 385).1 
These shoots produce numer- 
ous rhizoids (comp. Kuckuck, 
BATTEN) and such organs are 
also given off in number from 
the lowermost part of the erect 
shoots. The rhizoids are se- 
parated from the pericentral 
cell by a wall and contain 
numerous nuclei. The creeping 
shoots bear no trichoblasts but 
produce endogenous shoots; 
they are not much branched, 
most of the branches issuing 
from their proximal part. Some 
of these shoots, arising from 
the upper side, become erect, 
others, given off from the flanks 
or from the under side of the 
shoots grow out in a hori- 
: : Fig. 386. 
zontal direction. The branches p Se - ae 
UE : Polysiphonia atrorubescens. A, tip of tetraspore-bearing shoot with tricho- 
arising at a greater distance blasts. B, trichoblast. 200 : 1. 
from the base of the creeping 
shoots attain only a small size. The creeping shoots are usually somewhat incurved 
at the top, but not always upwards; they seem not to change from the horizontal 
to the vertical direction of growth, being transformed into erect shoot. 
The long erect shoots are densely tufted, issuing endogenously partly from the 
lowermost part of the erect filaments, partly from the innermost part of the creep- 
ing shoots. They bear no trichoblasts from the base to a comparatively great distance 
upwards; often more than the first twenty joints are without trichoblasts, but en- 
dogenous branches may occur in this part of the shoots. The trichoblasts are as a 
rule separated from each other by more than one joint, frequently by two or three 
7 Harvey incorrectly ascribes a scutate root to this species (Phye. Brit. 1. c.). 
