318 Causes and Course of Organic Evolution 



as running water; species of Lemanea, Tuomeya, Chantransia, 

 and Delesseria live in cold swiftly flowing brooks, etc. That 

 such forms have migrated rather recently from the sea will 

 be considered probable in all parts of this book; here it may 

 only be hinted that Bostrychia Moritziana, through its occur- 

 rence in fresh as well as in salt water, makes such migrations 

 plausible." But the entire evolutionary trend of the red 

 algae suggests such fresh- water origin. In tracing this we 

 would again commence Tx-ith the Cyanophycese. Amongst 

 the living genera of the latter many species are of a bluish 

 violet to violet color, a fact attested to by there being seven 

 species belonging to as many genera that bear the specific 

 name violacea. Some of these are fresh- water, others are 

 marine. The marine species Dermocarpa violacea may vary 

 in its cell-contents from violet to rose-red. Amongst some 

 of the fresh-water and marine Rhodophyceae the color varies 

 from bluish to purple-pink and crimson. This is due to the 

 pigment phycoerythrin, which Kutzing considered to be iden- 

 tical with the pigment of many purple-red or red Oscillatoriese. 



Some species of the genera Radaisia, Chamcesiphon and 

 Hyella of the Cyanophycese exhibit a cellular aspect, a color 

 relation, and a production of non-motile conidia that might 

 well cause them to rank as precursors of the Rhodophyceae. 

 Some of these are fresh-water, some brackish, and some marine 

 in habitat. Some are bluish, some purplish, and some purple- 

 pink to rose-colored. But such non-nucleate and asexual 

 orgauisms seem to be connected with primitive Rhodophy- 

 cese such as the Bangiacese and Helminthocladiese by nucleated 

 but asexual or doubtfully sexual genera like Bangiopsis, Goni- 

 otrichum, Phragnionema, Porphyridium, and Cyanoderma which 

 have adapted themselves to most diverse habitats and sur- 

 roundings. The resemblance of the first named three to 

 Bangia, Porphyra, and Erythrotrichea, specially when the latter 

 are in their youngest growth condition, also of Porphyridium 

 to ErythropeltiSy is, we would consider, more than a coincidence. 

 It suggests rather that, from ancient organisms related to 

 these, the Rhodophycese have slowly originated as a side-line 

 of evolutionary modification, which, starting from bluish 

 violet fresh-water and ultimately violet-red fresh- or salt- 

 water cyanophyceous or senii-rhodophyceous ancestry, have 



