..Bangiaceae - Eti Florideae Eugleneae Chi Iromonadinae Pleurococcaceae - Endosphaeraceae Volvocaceae hlorosphaeraceae ï¿½ CoNJuGA'rAE, Siphonales Tetrasporaceao Ulvaceae Confdyvaleb Characeae in the culminating stage of Fucus, where the oogonium is separated from the stalk-cell, so that unless it be contended that the Fucus is really a sporophyte which does not produce spores, and that the gametophyte is represented merely by the oogonium and antheridium, there is no semblance of alternation of generation in this case.
In Fucus and allied forms the spindle-fibres between the daughter nuclei disappear early and the new cell-wall is formed in the cytoplasm.
In the Algae, such as Fucus, Volvox, Oedogonium, Bulbochaete, and in the Fungus Monoblepharis, the spermatozoid is a small oval or elongate cell containing nucleus, cytoplasm and sometimes plastids.
Chara, Fucus, Ulva and Conferva, and in ï¿½ part Tremella and Byssus - would to-day, in any sense in which the term is employed, be regarded as algae.
On the British coasts zones are observable in passing from high to low water mark, characterized by the prevalence of different species, thus: - Pelvetia canaliculata, Fucus platycarpus, Fucus vesiculosus, Ascophyllum nodosum, Fucus serratus, Laminaria digitata.
In Fucus vesiculosus they arise in lateral pairs; in Ascophyllum they are single and median; in Macrocystis one vesicle arises at the base of each thallus segment; in Sargassum and Halidrys the vesicles arise on special branches.
Both organs may occur in one conceptacle, as in Pelvetia, or each may be confined to one conceptacle or even one plant, as in Fucus vesiculosus.
The oogonia arise on a stalk cell from the lining layer of the cavity, the contents dividing to form eight oospheres as in Fucus, four as in Ascophyllum, two as in Pelvetia, or one only as in Halidrys.
Fucus vesiculosus, young oogonium.
Fucus vesiculosus, discharge of eight oospheres from oogonium.
In some cases such as Delesseria, Neurymenia, Fucus, Alaria, the leaf-like structure is provided with a strengthening mid-rib, and when as in Delesseria it is also richly veined the resemblance to the leaf of a flowering plant is striking.
Strasburger, " Kerntheilung and Befruchtung bei Fucus," Cytologische Studien (Berlin, 1897); F.
Its chief constituent is mannite or manna sugar, a hexatomic alcohol, C6H8(OH)6, which likewise occurs, in much smaller quantity, in certain species of the brown seaweed, Fucus, and in plants of several widely separated natural orders.