1919] Setchell-Gardner : Myxophi/ceae 3 



Myxophyceae Stizenbergor, Dr. Ludwio; Rabonhorst's Algen Sach- 

 sens, 1860, p. 18. 



Myxophykca AVallroth, Fl. Crypt. Germ., vol. 2, 1833, p. 4. 



Gloesipheae Kiietz., Phycologia geiieralis, 1843, p. 179. 



Phycochromophyccae Rabenh., Fl. Eur. Alg., vol. 1, 1864, p. 1. 



Cryptophyccoe Thiirct, in Le Jolis, Liste des Alg. dii Cherbo\irg, 

 1863, p .13. 



Cyanophyceae Sachs, Lehrb. d. Bot., ed. 4, 1874, p. 248. • 



Schizophyceae Cohn, Ueber Thallophytsystem, 1879, p. 279. 



The Myxophyceae, or Cyanophyceae, as they are perhaps better 

 known, constitute a fairly compact and easily to be distinguished 

 group of more simple and smaller plants. The cell structure is simple 

 in tiiat the protoplast lacks the distinct differentiation into cytoplasm, 

 nucleus, and chromatophore found in other groups of the Thallophyta 

 and in the Embryophyta, and there is certainly no distinct mitosis. 

 The stature is slight as compared with that of plants of most other 

 groups, the largest plants being only a few centimeters high. The 

 morphological differentiation of the various genera and species is also 

 simple. The reproductive methods are very simple indeed, being 

 either pureh^ vegetative or by non-sexual spores. Neither sexual 

 reproduction nor zoospores are known in the Myxophyceae. Some 

 filamentous species are motile, at least under certain conditions, and 

 tiie hormogonia are said also, in the case of certain if not all species, 

 to be motile, although largely of microscopic or very slight dimensions. 

 The cells, colonies or filaments of most of the Myxophyceae occur in 

 such numbers and so densely aggregated, or even agglutinated together 

 as to form laj'ers or masses of various shapes which are sufficiently 

 conspicuous to be readily visible or even very noticeable. The 

 Myxophyceae inhabit damp places or shallow waters even at fairly 

 high temperature, and some non-marine members of the group even 

 ascend, in thermal waters, to about 77° C or possibly higher. The 

 Myxophyceae are often found in waters containing decomposing 

 organic material. Some of those inhabiting calcareous waters are 

 concerned in causing deposits of tufa or travertine, while some species 

 bore their way into shells. Some species in silicious thermal waters, 

 in turn, are closely associated with the deposit of sinter, IMany species 

 are epiphytic, some even are more or less deeply endophytic while 

 some are associated with fungi in lichen formation. 



The Jlyxophyceae do not seem to be closely related to the other 

 groups of Phycophj'ta although there are certainl}^ close resemblances 



