98 



SCIENCE PROGRESS 



that this tendency led in another direction to the evolution of 

 Pleurococcns (Artari 2, Chodat 12 and 13), which is best regarded 

 as a type reduced from a filamentous Ulotrichaceous ancestor 

 and only rarely forming zoospores (cf. however Wille 70a, p. 36); 

 this view is supported by the fact that under certain circum- 

 stances Pleurococcns may form short filaments (fig. 4, l). Another 

 tendency shown by the Ulotrichales is towards a terrestrial 



Fig. 4. 



A^ CEdogonium Borisiannm, Wittr. (cell-division), b, CEd. geme!H/>antm, Pringsh. (cap-cell), c, CEd. 

 concatenaium, Hass. (zoospore), d, Cylindroca^sa. involuia, Reinsch. E, Conferva bombycina (Ag.), 

 Lagerh. F, Botrydium granulatuin, Rost. et Wor. G, Spirotania condensaia, Breb. H, Meso- 

 ttFnium De Greyi, Turn. k, Cylindrocystis diplospora, Lund. l, Pleiavcoccus Niigeli, Chod. 

 M, Conferva bombycina (Ae.), Lagerh. (zoospore). N, C. bombycina (Ag.), Lagerh. (liberating 

 aplanospores). o, Ophiocytinm vzajus, Nageli. p, Chlorosaccus fluidus, Luther, (a and c after 

 Hirn ; B after Pringsheim ; d after Cienkowski ; e after Gay ; f after Rostafinski and Woronin ; 

 G-K after West and West ; l after Chodat ; M and P after Luther ; N after Oltmanns ; o after West.) 



habit (Chroolepideae, see Oltmanns 53, p. 247), an evolutionary 

 line showing some interesting parallels with the lower Fungi, 

 which lack of space, however, prevents our following up. An- 

 other prominent peculiarity of the Ulotrichales, the formation 

 of hairs, is not of any phylogenetic importance. 



All the different algal forms hitherto considered are at the 



