438 Dr. Griffith on Gallionella ferruginea. 



what I have deemed an error, but they may be useful as showing 

 us how cautious we should be in founding genera from frag- 

 ments : this is a most prolific cause of synonyms, with which no 

 science is so overloaded as geology. 



Cirencester, Sept. 1853. 



XLIV. — On Gallionella ferruginea {Ehrenb.). 

 By J. W. Griffith, M.D., F.L.S. 



In the water of bogs and pools, especially those containing much 

 iron in solution, there are occasionally found microscopic organ- 

 isms, myriads of which are aggregated around the living or dead 

 stems of plants contained in the water, and forming around 

 them reddish or yellowish brown flakes or filmy masses. The 

 general appearance of these organisms has been well described 

 by Ehrenberg in his great work on the Infusoria*, by whom they 

 were placed in the genus Gallionella, with the specific name fer- 

 ruginea. Mr. Ralfs places them among the Diatomacese, in the 

 genus Melosira, with the specific name ochracea f. As the wri- 

 tings of these authors are in every one^s hands, we shall pass 

 them over. The latest writer, Kiitzing, gives the following 

 generic and specific characters : — 



'* Glceotila, Kiitzing. — Trichomata eramosa viridia mucosa, ex cel- 

 lulis monogonimicis composita. — (Paludosse, inundatae.) Gl. fer- 

 ruginea. Kg. Phyc. Germ. p. 191. — G. ochracea, trichomatibus 

 brevissimis moniliformibus, articulis ovato-globosis. Diam. ^(J^qq'". 

 — Gallionella ferruginea, Ehrenb. Infus. t. 10. f. 7. — Melosira mi- 

 nutula, Brebiss. Falais. p. 42. pi. 5. — In fontibus martialibus (v. v.). 

 — Cf. Kg. Bacillar. p. 56, Gallionella ferruginea." 



Neither of these observers has detected their true structure ; 

 nor is this to be wondered at, for the filaments are exceedingly 

 minute (varying from the ^~ to -^^ inch in breadth, but gene- 

 rally from jp^ to 2j5^), and it requires no ordinary management 

 of the microscope to render it distinct. Each filament consists 

 of two interlacing fibres, forming flattened compound spirals. 

 The fibres are coloured by peroxide of iron ; but they contain no 

 silex, or at least not more than a mere trace, such as is natu- 

 rally invariably associated with the peroxide. If the filaments be 

 macerated for some time in distilled water, the fibres will sepa- 

 rate; but they may be clearly distinguished in the compound 

 filaments with the aid of a good object-glass of high power 

 (400 to 500 diameters) ; in fact they form an admirable test- 



* See Pritchard's History of Infusorial Animalcules, 1852. 

 t Ann. Nat. Hist. (1843) vol. xii. p. 351. 



