FUCI. 
s, or marine conferve, from those 
last longitudinal 
| seme ehehy te Tiectahe 
quite homogeneous. In the former, the tissue ap- 
es ene eee es Soy ad for i 
‘the colour varies. Some of the small cylindrical fuci 
acquire the ap t 
tions aeee pember time of fructification ; ae per- 
fe ucing these partitions, to give firmness to 
re ae orto delay the circulation of the juices, and 
make them undergo a more complete elaboration at this 
crisis. It was first observed by Mr Dillwyn, that the 
aculei of F. aculeatus are regularly jointed, and that 
‘it is without joints. © — 
e ee. ‘of ‘fuci has» more uni- 
b erin and: ly conspi 
« vesiculosus and nodgsus. (See Plate CCLXI. 
Fig. 4; 5.) They are now generally denominated Air- 
vesicles, or simply Vesicles. Most ofthe sea-weeds ha- 
Ratha yproaching to ligneous, are provided 
ith distinct air-vesicles ; and those that are not so pro- 
vided, have in their stems empty spaces, sometimes visi- 
ble to the naked eye. These probably serve the pur- 
pose of air-vessels: they. ‘from the root or base, 
rise with the stem, and disappearin the frond. 
Formerly, the, air-vesicles.. were. generally. supposed 
to be the male fructification. e generic character of 
Fucas, given by Linnaeus, was the following: Mole, 
Vesicles smooth, hollow, with villose hairs within, in- 
peice ' Female, Vesicles smooth, filled with jelly, 
inkled with immersed grains, minent at the ti 
oot ary.” sc sbbaplianieasion to himself ‘the 
application of this character to the common F. nodosus, 
he will eive, that by male vesicles must be meant 
the air- 3 and by female vesicles, the les, 
the immersed grains prominent at the tip, bemg a suffi- 
ciently ok deseiigsion of the tubercles. They were 
ric air as land plants, The ligneous fucacez, he says, 
absorb oxygen during the night, and give it out durin 
the day, though in very small quantity. Analogy wou 
lead us to consider this statement as probably correct ; 
but whether it is founded on direct experiment, is not 
explained by the author. The Floridew, he adds, exhale 
less oxygen than the former. They ret 
. opinion, in order to produce the brilliant tints which 
dorn ites © v0 ee like herbaceous land plants, 
give out by the action of a great ity of oxy- 
gen gas, and a little istic clit ‘Ths datacepaahie 
of the atmospheric air must take place in the vesicles, 
or inthe apacey or valle alaeally-allided! te: these per- 
haps at once serving as reservoirs, and as ans for 
ey. Ag air. On some species, vesicles have 
never yet been found; but Turner is ineli to 
retain it, in his - 
13 
think, that none are entirely and’ at all times destitute 
of them; so that the division ‘* absque vesiculis” might 
be given up. NW 
Many fuci, such asthe common F, vesiculosus 
and serratus, have small tufts of white filaments like 
hairs scattered over their surface, Reaumur conjectu- 
red, that these might be a sort of male flowers, and as 
such he described them. _ In this notion, he was follow- 
ed by some distinguished botanists. But they are now 
known to. be analogous merely to the hairs on land 
plants, and to be useful bably for the secretion or 
ion of particular fluids. It has generally been 
said; that they’ occur on the plant in every stage of its 
ate hw ana at all seasons of the year. Lamouroux, 
ever, asserts, that they are not permanent, but disap- 
pear at certain seasons, and at certain stages of the life 
of the plant. They are never seen on the stem or the 
nerye, but on the frond only. 
It does not appear » le that the submersed al- 
gee derive much of their nourishment from the processes 
by which they ‘are attached to rocks or other substan- 
ces, although these processes in many instances resem- 
ble roots, and usually receive that name. It appears 
likely; that the principal part of ‘their food is imbibed 
by their gen surface. They are attached to rocks 
of mica-slate, greenstone, basalt, sandstone, and lime- 
stone. Many of the smaller kinds grow on the stems of 
the larger plants. It is to be observed, however, that 
Mr Turner;‘in the introduction to his Synopsis of Bris 
tish Fuci; hints it as his opinion, that the root-like pro- 
cesses are not merely intended for fixing the plants, 
but are to.a certain degree useful as organs of nutrition ; 
and he mentions that some species seem peculiar tochalk, 
some 'to , and others to still harder rocks. On 
the other hand, at least one species, Fucus bacciferus of 
Turner, '(t.'47), has never been found with a root or 
base: it evidently lives and increases while floating 
about. ‘The ‘extensive meadows of 'sea-weeds through 
Fuci. 
_—— 
Pencils of 
white hairs. 
Food of 
sea-weeds. 
which navigators to distant countries continue to sail for - 
days in the unfathomable ocean, and which are found 
ina fresh and growing state,afford convincing evidence 
that certain kinds of fuci at least are not entirely, nor 
even chiefly, dependent’on their roots for nourishment. 
M. Desvaux, editor of the Journal de Botanique, has 
lately made a direct experiment on this subject. Ha- 
ving detached some fuci above the roots, he fixed them 
to stones by means of cords or other artificial methods, 
and plunged them again in the sea. Having visited 
them some time after, he found that they had increased 
very sensibly. 
authors have supposed that the fuci are nou- 
vished by their mucilage : but this is only removing the 
diffi ‘one step ; and besides, particular species, as 
F. esculentus, possess little or no mucilage. It has 
been remarked, however, that the cups or dises of F. 
loreus become flaccid and destitute ‘of juice, whenever 
the thongs of the plant have attained full size; and this 
has been ascribed to the exhaustion of the mucilage by 
their growth. 
The Caulerpz of Lamouroux creep in the.sand, and . 
seem to true roots ; but these, though at pre- 
sent associated with the fuci, form not only a very dis- 
tinct genus, but a separate family. 
Colours of Fuci. - 
The colours of sea-weeds have not yet been much 
attended to. A proportion of the fuci are of 
an olive hue; olive brown, olive yellow, or olive 
green. A good many are red or brownish red. Some 
are verdigris green, particularly F. eruginosus, (Turn. 
Colours of 
sea- weeds, 
