130 Bibliographical Notices. 



nothing more tlian the mixture of chlorophyll with other various colour- 

 ing-matters, whose peculiarities have hitherto only been satisfactorily 

 ascertained in a few instances." 



The tint of phycoehrom is so easily distinguishable by the eye 

 from the other colouring-matters of Algie, that there is a tempta- 

 tion to combine together all those plants whose cells contain it ; but 

 the class (Fhi/cocJiror.wphijce'e) can only be looked upon as provisional, 

 as a sort of " refugium " for a vast number of heterogeneous or- 

 ganisms, few if any of which are really autonomous. It may not 

 be without interest to go shortly through the orders and families 

 into which the class is divided, and to call attention to some of the 

 genera whose right to the designation of Algaj has been called in 

 question. 



Dr. Ilabenhorst divides his Phycochromophycece into two orders, 

 the Cystipliorce and the Nematoyence. The Cystlphone consist of 

 one fimily, the Chroococcacece ; and the Nematoyence of five families, 

 the OsciUariaceo', the Nostochacece, the Kivulariacece, the Scytone- 

 macecB, and Sirosiphonacefn. 



With regard to the Chroococcacecp, it is highly probable that 

 many of the so-called genera of the family arc nothing more than 

 phases of the gonidia of lichens. This notion has been making pro- 

 gress lately ; but its origin is not of very recent date. In one of 

 the latest papers* on the subject. Dr. Itzigsohn gives the result of 

 a series of observations on the culture of the gonidia of Peltiyera 

 canina. He says that the mode of growth observed in them iden- 

 tifies these gonidia entirely with the Chroococcacece, and that in the 

 process of development he has seen them assume the foi'ms of the 

 genera Ghi-ocapsa, GJoeofhece, and Aplianotliece. 



Again, ;^[essrs. Famintzin and Boranetzky, in their observations 

 in the ' Memoires de I'Acad. de St. Petersbourg ' (which arc to be 

 found also in the * Botanische Zeituug' for March 13, 18G8, and 

 in the 8th volume of the current series of the ' Annales des 

 Sciences Naturellcs '), have arrived at the conclusion that Cysto- 

 cocciis and Pohjcoccus (to say nothing of Nostoc) are only states of 

 the gonidia of lichens. If this be true of Cjistococcus and Poly- 

 cocciis, it is hardly possible to doubt that the same will be eventually 

 proved to be the case with such genera as Aphanocapsa, Micro- 

 cystis, Anacystis, Pohjcystis, and Coelosphcprium, as also with Homa- 

 lococcus, which consists of one species, the Coccochloris hyalina of 

 Meneghini. It is hardly too much to say that Gomphosphcma is 

 not geuerically distinguishable from Glceocapsci ; and, considering 

 what is now known, it may safely be asserted that no one would, 

 at the present day, think of making a genus of Chroococcus or 

 SynecJiococcus. With the above eliminations the family of the 

 Chroococcacece would be reduced to the genera Clathrocystis, Me- 

 rismopcedia , and Oncohyrm. Clathrocystis was established by Pro- 

 fessor Henfrey in the ' Microscopical Journal ' for 1855. He seems 

 to have separated it from Polycystis only because that name 



* Botanische Zeitung, March 20, 1868. 



