ALGALS. 



iiieredulous as to the possibility of the same object being at one time endowed more 

 especially with animal, and at another with vegetable life. Late observations on the 

 reproductive bodies of some AlgcC show that theii* motion is produced by ^^bratile cilia, 

 exactly in the same way as in certain animals. But it is exceedingly difficult to 

 imagine the transformation of one real species into another. The same species may 

 assume a vast variety of forms according to varying circumstances, and it is highly 

 instructive to observe these changes ; but that the same spore should under thfferent 

 circumstances be capable of producing beings of an almost entirely different nature, 

 each capable of reproducing its species, is a matter which ought not to be admitted 

 generally without the strictest proof." 



V For what wise purpose the Creator has filled the sea and the rivers with countless 

 myriads of such plants, so that the Flora of the deep waters is as extensive as that of 

 dry land, we can only conjecture ; the uses to which they are applied by man arc, 

 doubtless, of but secondary considei"atiou ; and yet they are of no little unportance in 

 the manufactui'es and domestic economy of the human race. One of the most curious 

 facts connected with them is their property of growing occasionally upon living 

 animals, which they destroy ; this is the case with Achlya prohfera, to be hereafter 

 noticed. 



Their history and classification have occupied the attention of some of the most 

 acute botanists of the present day. Bishop Agardh and his son, Greville, Harvey, 

 Decaisne, and KUtzmg, deserve to be especially named as most excellent and skilful 

 investigators of a very obscure and difficult subject. It is those only who have made 

 the subject their peculiar study who can determine which of the classifications proposed 

 by these authors has the strongest claim on attention. I, at least, am unable to decide ; 

 and therefore I have prefeii'ed to employ the arrangement made use of by Endlieher 

 in his last Supplement, as that which is most likely to be permanently employed for 

 some years to come. Those who wish to acquaint themselves with the views of the 

 great Algologists of the day should consult the younger Agardh 's AlgcB Maris Mediter- 

 ranei,ii;c. (1842) ; Greville's Algce Britannicce (1830) ; Harvey's Mamial of British 

 AlgcB (1841) ; Decaisne's papers in the Annales cles Sciences Naturelles, 2 Series, 

 vol. xvii. (1842) ; Kiitzing's Phycologia generalis, ocler Anatomic, Physiologic unci Sys- 

 temkunde cler Tange (1843), a most elaborate work, illustrated with eighty exquisite 

 plates ; the Kiesclchaligen Bacillaricn oder Diatomeen by the same author, with three 

 plates, 1844, which we regret to say we know only by name ; the yoimger Agardli's 

 Adversaria in Systemata Algarum hodicrna, 1844, and various papers of Br. Montague. 



Natural Orders of Algals. 



Crystalline, angular, fragmentary bodies, brittle, and midtiplying &yl j Di\tomace^ 



sjJontaneous separation J 



Vesicular, filamentary or membranous bodies, nmltiplied by zoospores \ 2 Conferv\ce^ 



generated in the interior at the expense of their green matter . . . J "^ 

 Cellular or iubidar unsymmctrical bodies, midtiplied by simple spores \^ Fucace^e 



formed cxtanicdly J 



Cellular or tidndccr unsymmetriccd bodies, midtiplied by tetrasporcs . 4 Ceramiaceje. 

 Tabular symmetrically branched bodies, midtiplied by spired coated'X^ Charace^ 



nucules, filled ivith starch J 



*^* For the information of those who may wish to know something of the system of 

 Kiitzing, which I do not adopt, the following Hst is extracted from his gi-eat work, to 

 which the reader is referred for an explanation of the peculiar \news of its author. 



* I. CLASS.— ISOCARPE^E. 



Tribus I. — Gymnospermece. 

 Order I.— EREMOSPERME/E. 



Si'honlo I. — Mycophi/ctYP. 



I. Cryptococce.e. — Crj'ptococcus, Ulvina, Sphae- 



rotilus. 



II. Leptoihite.e. — Hygrocrocis, Sirocrocis, Lep- 



tomitus, Mycotiiamnion, Chameenema, IS'e- 

 matococcus, Cliionyphe. 



III. Saprolegnie.e. — SaprolegTiia, Mycocceliuro . 



IV. Ph.=1!one.me.e. — Stereonema, Phseonema. 



Subordo II. — ChamcephycetP. 



V. Desmidie.'e.- Closterium, aiicrotheca, Penta- 



sterias, Euastruni, Xanthidium, Stauras- 

 trum, Crucigenia, Meiismopoedia, Sceno- 

 desmus, Tessai-thra, Micrasterias, Sphaeras- 



trum, Gomphosphaeria, Desmidium, Didy- 

 moprium. 



VI. Palmelle^.— Protococcus, Microhaloa, Bo- 



tryocystis, Microcystis, Botrydina, Polycoc- 

 cus, Palmella, Inoderma, Coecochloris, 

 Glceocapsa, Tetraspora, Palmogloea. 



VII. Hydeococce.e. — Actinococcus, Entophysa- 



lis, Ilydrococcus, Ilydrurus, Helmintho- 

 nema. 



Sifb<yrdo m.—Tiloblnska. 

 A. Glceosiphe.e. 



a.) Asemospemiea?. 



VIII. Oscillarie.e.— Spirulina, Oscillaria, x\cti- 

 iiocephalus, Phorniidium, Ilydrocoleuin, 

 Chthonoblastus. 



