ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 303 



preceded bv nitrogen-fixing Bacteria. Who can say ? Brnnnthaler 

 cleverly argues that the red Algti3 are the oldest, and the green the 

 youngest group ; and the Flagellata have developed independently. 



2. General character?; of the Flagellata. Klebs distinguished the 

 group from the Chlamydonionads (motile unicellular green alga^) by a 

 number of characters, including amoeboid changes in the periplast ; 

 nutrition either holozoic, saprophytic, or holophytic : entire absence of 

 pyrenuids and of starch ; reproduction by simple longitudinal fission ; 

 absence of gamogenesis. Senn in 1900 grouped the Flagellata in seven 

 divisions — three containing colourless heterotrophic forms, and four 

 pigmented and mainly holophytic. Of the latter four the Chryso- 

 monadineee. with brown chromatophores and producing oil and leucosin, 

 point to the Diatoms and brown Algas ; the CryptomonadineEe, variously 

 coloured and producing starch, may have given rise to the Peridiniales 

 and green Algae : the Chloromonadineae and Eugleninese contain 

 numerous green chromatophores, contractile vacuoles, etc. Cavers 

 recognizes three main lines of descent leading (1) from the simpler 

 Chloromonads to the Heterokontse ; (2) from the Polyblepharids to the 

 .Chlamydomonads and on to the Isokonta^ and other green Alga? : (o) 

 from the Chrysomonads and Cryptomonads to the brown Algse, Peri- 

 diniales, etc. 



3. Chloromonads and Heterokoutee (with two flagella of unequal 

 length). This is the yellow-green group, Confervales, producing oil 

 and not starch. Some recent papers are reviewed ; and a table of the 

 tribes, families, and genera is drawn up. 



•4. Ptelation of green Algge to Chlamydomonads. Papers by Chodat, 

 Blackman, and others, are discussed ; and a diagrammatic phylogeny is 

 shown of the (1) Polyblepharid and Chlamydomonad ; (2) the Chloro- 

 monad ; and (3) the Chrysomonad and Cryptomonad lines, being an 

 indication of how the majority of the green Alga? may be derived from 

 Flagellate ancestors with two or more equal flagella. 



5. A^olvocales. The Polyblepharid acese are discussed, and are shown 

 to contain a remarkable series of transitional forms leading from the 

 Flagellata up to the Chlamydomonads. The Carteriaceae and Sphge- 

 rellaceie are reviewed in a similar way, typical forms being figured. 



Microflora.* — A. Pascher continues his contributions to the study of 

 our microflora. In his second paper he discusses the genus Tetraedron, 

 into which many organisms have been placed which are only stages in 

 the life-history of other known Algae. He then describes a new genus, 

 Pseudotetraedron, which is distinguished by the division of the mem- 

 brane into two parts, by the disk-shaped chromatophores, etc. The 

 author thinks his new genus may be identical with Bachmann's Foly- 

 edriinn, from the Red Sea. Pseudotetraedron belongs to the Heterokontae, 

 in the Chlorobotrydaceae. P. neglect inn was found in Bohemia. 



The third contribution of this author deals with the systematic 

 division of the Heterokontae. After a short general discussion of the 

 class, he points out that the various stages of development of the 

 Heterokontae correspond with those of the Chlorophyce^, and draws up 



* Hedwigia, liii. (1912) pp. 1-5, 6-22 (figs.). 



