130 Bibliographical Notices. 



nothinpr more than the mixture of chlorophyll with other various colour- 

 iutr-matters, whose peculiarities have hithorto ouly been satisfactorily 

 ascertained in a few instances." 



The tint of phycochrom is so easily distinjjuishable by the eye 

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

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

 the class {^Phi/cochnn.iojiJn/otp) can only be looked njion as provisional, 

 as n sort of " rofugium " for a vast number of hoterogeneons 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 whot^e right to the designation of Alga3 has been called in 

 question. 



Dr. Eabenhorst divides his Phycochtomophilcect into two orders, 

 the Cijstiphonv and the Xemator/etia-. The Ci/stij^horce consist of 

 one family, the Chroococracecp ; and the Nematogeno' of five families, 

 the Oscillarinceip, the Nosiochacece , the liivulariacece, the Seytone- 

 macecf, and Sirosiphonacerp. 



With regard to the Chroococcacecp, it is highly probable that 

 many of the so-called genera of the family are 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 PeJtigera 

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

 tities these gonidia entirely with the Chroococcaccfe, and that in the 

 process of development he has seen them assume the forms of the 

 genera GJctocopsa, Glceothece, and Aplmnothece. 



Again, Messrs. Famintzin and Boranetzky, in their observations 

 in the ' Memoires de TAcad. de St. Petersbourg ' (which are to be 

 found also in the ' Botanische Zeitung' for March 13, 1S08, and 

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

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

 cocciis and Polycoccus (to say nothing of Nostor) are only states of 

 the gonidia of lichens. If this be trae of Cystococcus and Poly- 

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

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

 ci/stif;, Anacystis, Pohjcystis, and Coelosphrvrium, as also with Homa- 

 lococciis, which consists of one species, the CoccochJoris hyal'nui of 

 Meneghini. It is hardly too much to say that Gomphosj^Juma is 

 not geiierically distinguishable from Glieocapsa ; 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 Chroococats or 

 Synecliococnis. AVith the above eliminations the family of the 

 Chroococcac^ip. would be reduced to the genera CJathrocystis, Me- 

 nxmopcTdia , and Oiicohyrsa. Claihrocystis was established by Pro- 

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

 to have separated it from Polyrysfis only because that name 



• Botanische Zeitimg, March 20, 18G8. 



