32 Algce 



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

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

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

 Bacillariea? and the Flagellate Peridiniese than is at first apparent. 



The origin of the large class Rhodophycea? is still very un- 

 certain, although quite recently a marine Flagellate with the 

 chromatophores of the Rhodophyceas 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 Myxophyceas 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 ' Myxophycea? ' 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 Alga? were arranged by Wille, the Bacillariea? by Schtitt, 

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

 the removal of the Conjugate from the Chlorophycea?, 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 Conjugate as an order of Chlorophyceas 3 . 



The most recent classification of Green Alga? in English is that 

 put forward by Blackmail 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 "Stephanokontse") 

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

 Chlorophycea?, which are placed under the " Isokonta3." This 

 arrangement is based upon the assumption that the CEdogoniales 

 and the Conjugate are phylogenetically independent of the 

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



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

 - Hansgirg, 'Noch einmal liber die Phykochromaceen-Sch warmer,' Bot. Cen- 

 tralbl. Bd xxiv, 1885. 



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

 H. 1, Kristiania, 1901. 



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

 Green Algae,' The New Phytologist, 1902. 



