The study of phylogeny has suggested fourteen classes arranged in the following sequence: (1) Bacteria; (2) Cyanophyceae (Blue-green algae); (3) Flagellatae; (4) Myxomycetes (Slime-fungi); (5) Pendineae; (6) Conjugatae; (7) Diatomaceae (Diatoms); (8) Fleteroconteae; (9) Chlorophyceae (Green Algae); (10) Characeae (Stoneworts); (II) Rhodophyceae (Red Algae); (12) Eumycetes (Fungi);
The algal fungi, Phycomycetes, are obviously derived from the Green Algae, while the remaining Fungi, the Eumycetes, appear to have sprung from the same stock as the Rhodophyceae.
None of the existing Red Seaweeds (Rhodophyceae) has a unicellular body.
Rhodophyceae, or Red Algae.
Unknown in Cyanophyceae and Phoeophyceae, known only in Bangiaceae and Nemalion among Rhodophyceae, they are of frequent occurrence among Chlorophyceae, excepting Characeae.
Rhodophyceae, or Florideae.
Rhodophyceae are mostly marine, but not exclusively so.
Most of the larger species of marine Rhodophyceae are attached by means of a disc to rocks, stones or shells.
No unicellular Rhodophyceae are known, although a flagellate organism, Rhodomonas, has recently been described as possessed of the same red colouring matter.
- Rhodophyceae, variously magnified.
A census of Rhodophyceae is furnished below: - (i) Bangiaceae-4 families, 9 genera, 58 species.
Finally, while Chlorophyceae and Phaeophyceae exhibit important affinities, the Rhodophyceae are so distinct that the term " algae " cannot be made to include them, except when used in its widest sense.
Turn ing first to the Rhodophyceae, both on account of the high place which they occupy among algae and also the remarkable uniformity in their reproductive processes, it is clear that, as is the case among Archegoniatae, the product of the sexual act never germinates directly into a plant which gives rise to the sexual organs.
Even among Bangiaceae the carpospores arise from the fertilized cell by division, while in all other Rhodophyceae the oospore, as it may be called, gives rise to a filamentous structure, varying greatly in its dimensions, epiphytic, and to a large extent parasitic upon the egg-bearing parent plant, and in the end giving rise to carpospores in the terminal cells of certain branches.
(For the remarkable symbiotism between algae and fungi see Fungi and Lichens.) Most algae, particularly Phaeophyceae and Rhodophyceae, spend the whole of the life-cycle immersed in water.
The presence of phycocyanin, phyco a role in the morphological development of land plants is entirely wanting in algae, such conducting tissues as do exist in the larger Phaeophyceae and Rhodophyceae serving rather for the convection of elaborated organic substance, and being thus comparable with the phloem of the higher plants.
Schmitz, P. Falkenberg, P. Hauptfleisch, " Rhodophyceae," in Engler and Prantl's Pflanzenfamilien (1897); W.