178 



HARDWICKE'S SCIENCE- GO SSIP. 



[Aug. 1, 1867. 



PHYLLACTIDIUM. 



SEVERAL correspondents having applied for 

 information concerning the freshwater plant 

 called Phyllactidium pulchellum ; we have resolved 

 upon communicating a few paragraphs of its history. 

 During the spring of 1866, Mr. Aylward, of Man- 

 chester, sent us, for determination, some curious 

 little green discs which had grown in a bottle of 

 water collected in the previous autumn from a small 

 pond near the new Assize Court, Manchester. When 

 collected, this water contained Volvox globator in 

 abundance, but no discs ; during winter all traces 

 of Volvox disappeared, and the little green discs 

 supplied their place. At first, and for some time, 

 Mr. Aylward suspected that they were a condition 

 of Volvox, and sent us the discs to be named, these 

 were submitted to Dr. Gray, E.R.S., whom we 

 knew to have been for very many years deeply in- 

 terested in Algse (indeed, almost a walking polyglot 

 of all forms of vegetable and animal life), and in 

 July, 1866, a description of these discs, under the 

 name of Phyllactidium pulchellum, appeared in 

 Seemann's "Journal of Botany," contributed by 

 Dr. Gray, in which the scientific affinities of the 

 plant were discussed, and much useful information 

 supplied. 



This discoid water-weed received the above 

 names, generic and specific, from Kutzing, who 

 appears to have been the first to observe it, and we 

 gather from a private letter, from this author, that 

 he first found it in his fresh-water aquarium which 

 he had in 1838-10, in his study. He found about 

 seven or eight specimens of various sizes attached 

 to the glass, and took a drawing of several of them, 

 afterwards describing the plant in his " Phycologia," 

 under the name which it still bears, but he does not 

 seem to have met with it again, or in any other situa- 

 tion. When Dr. Gray wrote the account above 

 alluded to, he was under the impression that it had 

 not been before observed in Great Britain ; but, 

 within a few days after its appearance, Professor 

 Balfour stated at a meeting of the Botanical Society 

 of Edinburgh, that it was found thirteen years ago 

 in Scotland by Mr. George Lawson, in the water of 

 a vase at the Royal Botanic Gardens, and specimens 

 were exhibited under the microscope which were 

 put up at that time by Mr. Lawson. In December, 

 1866, Dr. Gray communicated to the "Journal of 

 Botany " an additional note on Phyllactidium, in 

 which he announced the discovery of a still older 

 authority for this plant in Britain, for that Mr. 

 Ralfs had read a paper before the Botanical Society 

 of Edinburgh in December, 1841, which was printed 

 in the "Annals of Natural History" in 1815 (vol. xvi. 

 p. 308), in which the same plant was described and 

 figured under the name of Coleochcete scutata. He 

 also says that he sent specimens to Professor Kiitz- 

 ing, and that gentleman considered it to be the 



same as his Phyllactidium pulchellum. Hence it 

 was known in Britain in 1S11, and the merit of dis- 

 covery is due to Mr. Ralfs, who adds to his account 

 that he was indebted to Dr. Dickie for determining 

 its name. It is also somewhat singular that Mr. 

 Ralfs gives so many stations for this plant, as, 

 Victoria Park and Windermere, on the authority of 

 Mr. Sidebottom ; Aberdeen, where it was found by 

 Dr. Dickie; Henfield, and near Tunbridge Wells, 

 as communicated by Mr. Jenner ; near Pleetwood, on 

 the authority of Mr. J. S. Ashworth ; near Bristol, 

 found by Mr. Thwaites ; ponds at Singleton and 

 Sketty, near Swansea, accordiug to Mr. Moggridge ; 

 also abundant in Cromlyn Bogs, near the same 

 town, and in several stations near Penzance and 

 Dolgelly. 





HEW''* ' ■ ■ '-^m:W^ r >'' 



Fig. 180. Phyllactidium pulchellum magnified. 



So much for the history of this interesting plant 

 which we have figured from a specimen furnished to 

 us by Mr. Aylward. We will not follow Dr. Gray 

 in discussing whether it should be called Phyllacti- 

 dium or Coleochcete, or Bulbochcete, but refer those 

 interested in the more technical phases of the 

 subject to Dr. Gray's two communications in the 

 " Journal of Botany " for 1866. For the sake of those 

 who may still be strangers to this organism we give 

 Dr. Gray's excellent description. "The form is 

 discoidal, circular, slightly concave on one side, 

 formed of very many minute, nearly equal-sized ; 

 square cells, placed on forked lines regularly spread- 

 ing from a central cell to the circumference ; the 

 frond is thin, membranaceous, and the upper and 

 under surfaces are similar. The fructification con- 

 sists of 12 to 16 square thickened patches, forming 

 a circle (sometimes two) rather nearer the margin 

 than the centre of the disc, the square patches being 

 often placed in pairs. The fructification was first 

 observed, and is well figured by Suringar, in his 

 thesis entitled ' Observations Physiologies, ' 

 delivered in Leyden on the 3rd of March, 1857, 

 (p. 26, fig. 4, a)." The student may also consult 

 Dr. Pringsheim's monograph of the genus Bul- 

 bochcete in his "Jahrbucher," vol. vii., for I860. 



We shall be happy to record additional localities, 

 if authenticated by the name aud address of the 

 writer. 



