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);
Thus simple forms included in the Heteroconteae, Chlorophyceae and Phaeophyceae show an obvious connection with the Flagellatae; the Peridineae may be regarded as a further developed branch; the Conjugatae and Diatomaceae cannot be directly connected; the origin of the Rhodophyceae is also obscure; while the Characeae are an advanced and isolated group (see ALGAE).
It consists of three subdivisions - Conjugatae, Euchlorophyceae and Characeae.
In consonance with this name, its authors propose to re-name the Conjugatae; Akontae and Oedogoniaceae with a chaplet of cilia become Stephanokontae, and the algae remaining over in the three series from which the Heterokontae and Stephanokontae are withdrawn become Isokontae.
Conjugatae, Protococcales and Characeae are exclusively freshwater; Confervales and Siphonales are both freshwater and marine, but the latter group attains its greatest development in the sea.
In all Conjugatae and most have the same unlimited growth as the main axis.
Among Conjugatae reproduction is effected solely by means of conjugation of what are literally aplanospores.
Again, while Conjugatae may be shut out from Chlorophyceae as an independent group co-ordinate with them in rank, the Characeae constitute so aberrant a group that it has even been proposed to raise them as Charophyta to the dignity of a main division co-ordinate with Thallophyta.
Nor must we overlook the possibility that the endosporeformation in non-motile bacteria more than merely resembles the development of azygospores in the Conjugatae, and some Ulothricaceae, if reduced in size, would resemble them.