32 Algce 



line of descent. They are regarded by some as a group of the 

 Phaeophyceae, but are better considered as a distinct class. It 

 may be that there is a much more direct relationship between the 

 Bacillarieae and the Flagellate Peridinieae than is at first apparent. 



The origin of the large class Rhodophyceae is still very un- 

 certain, although quite recently a marine Flagellate with the 

 chromatophores of the Rhodophyceae has been discovered by 

 Karsten 1 . As there are so few freshwater representatives of this 

 large class of Algae, a discussion as to their origin would here be 

 out of place. 



So little is known concerning the Myxophyceae and their life- 

 histories that any attempt to give an account of their origin and 

 evolution would be mostly a matter of conjecture. It is interesting 

 to note, however, the existence of blue-green motile organisms 

 such as Cryptoglena Ehrenb. and Chroomonas Hansg. 2 Reasons 

 for retaining the word 'Myxophyceae' are stated in the Intro- 

 duction (page 3). 



The classification commonly adopted at the present time is the 

 one found in Engler and Prantl's ' Pflanzenfamilien,' in which 

 the Green Algae were arranged by Wille, the Bacillarieae by Schiitt, 

 and the Blue-green Algae by Kirchner. Wille followed Sachs in 

 the removal of the Conjugatae from the Chlorophycese, but the 

 reasons for this are certainly insufficient. It is also significant to 

 note that since the publication of the classification referred to, 

 Wille has regarded the Conjugatae as an order of Chlorophyceae 3 . 



The most recent classification of Green Algae in English is that 

 put forward by Blackman and Tansley 4 in the ' New Phytologist ' 

 for 1902, and they not only accept at the outset the principal 

 changes suggested by Luther and Bohlin, but carry them still 

 further. They separate the CEdogoniales (as the "Stephanokontae") 

 and the Conjugatae (as the "Akontae") from all the rest of the 

 Chlorophyceae, which are placed under the "Isokontae." This 

 arrangement is based upon the assumption that the CEdogoniales 

 and the Conjugatae are phylogenetically independent of the 

 " Isokontae," and that all three groups have arisen from the 



1 Karsten in Wissensch. Meeresuntersuchungen, Kiel, Bd iii, Heft 2, 1898. 



2 Hansgirg, ' Noch einmal iiber die Phykochromaceen-Schwarmer,' Bot. Cen- 

 tralbl. Bd xxiv, 1885. 



3 Wille, ' Algologische Notizen vn, vni,' Nyt Magazin f. Naturvidensk., B. 39, 

 H. 1, Kristiania, 1901. 



4 F. F. Blackman and A. G. Tansley, 'A Kevision of the Classification of the 

 Green Algse,' The New Phytologist, 1902. 



