HAPALOSIPHON. 275 



Genus 92, HAPALOSIPHON, Naeg. 



Forming tufts, attached or floating, olive green, aeruginous, 

 or with age light or darker brown, branched ; branches ordi- 

 narily simple, springing ,at right angles, or nearly so, from the 

 prostrate stem ; sometimes with secondary branchlets. Cells in 

 a single series, distinct, or sometimes continuous, granulate. 

 Heterocysts occur not infrequently. Inhabits submarine, as well 

 as fresh waters. 



Dr. Itzigsohn, of Prussia, made an elaborate study of the life- 

 history of plants of this genus, particularly of H. Braunii, de- 

 voting two years to it. He gathered fresh material from a pond 

 near his home at least once a week. In the winter months he 

 obtained his specimens from under the ice. He was abundantly 

 rewarded for his labors, making many very important and val- 

 uable observations heretofore unknown, and so new to science 

 that the value of his work was not credited at the time. Even 

 now, after a lapse of more than thirty years, it is only here and 

 there that the correctness of his observations is accepted. Old 

 theories, numerous genera and a multitude of species are ad- 

 mitted, which have no value as species. In the life-history of 

 this one plant, in its numerous polymorphic transition -forms of 

 development, occur conditions of plant-life corresponding with 

 such genera as Chroococcus, Naeg., Aphanotheca, Naeg., Aphano- 

 capsa, Naeg., Microcystis, Kg., Nostoc, Vauch., Hormosiplion, Kg.. 

 Rivularia, Ag., Gloeocapsa, Kg., ftynechococcus, Naeg., and others, 

 each distinctly characteristic, and yet all of them only links in 

 the chain of evolutions necessary to their propagation ; some of 

 them may be abnormal conditions or freaks. Dr. Itzigsohn satis- 

 fied himself that all of the many forms described are connected 

 with the present plant, but he failed to find the precise relation 

 of each to each. 



For full particulars consult "tiMzzen zu einer Lebensgexehichte 

 des Hapalosiphon BrauniiJ' 49 pp. 5 Plates, by H. Itzigsohn. 



HAPALOSIPHON BRAUNII, Kg. 



Floccose caespitose, often parasitic, attached, or floating ; 

 aeruginous, lighter or darker olive brown ; filaments loosely 

 interwoven ; interior trichomes usually light aeruginous ; 

 articulations of stems distinct, about as long as wide or 

 shorter, granular ; sheath thin and close, colorless, rarely 

 yellowish. 



Diameter of filaments, 10-12 /^. 



Primarily parasitic on submerged plants, later floating, 

 sometimes in large masses. 



