THE OSCILLARIA PHARAONIS. 



[From a Foreign Correspondent]. 



M. de Bribisson has communicated to the last meeting of the Academical 

 Society of Falaise, an interesting account of a rare and but little known species of 

 Alga — the Oscillaria Pharaonis. The coloured liquid formed by its prompt de- 

 composition, presents a remarkable phenomenon, hitherto not sufficiently studied. 

 The water in which this hydrophite has been deposited immediately after its being 

 gathered, assumes a tinge of deep red, either ochreous or blood-coloured, when 

 examined in a deep place or in an opaque vessel : but, on the contrary, if this 

 water is placed between the eye and the light, in a thin diaphanous vessel, the 

 colour assumes a beautiful indigo-blue tinge. A bottle filled with this liquid 

 appears, in the sun, blue on one side and red on the other ; thus it may be said 

 that this liquid in decomposing the rays of light, only permits the blue rays to 

 pass, and reflects the red only. White paper plunged in this liquid always takes 

 an azure colour, and never a red tinge. 



Bovy de St. Vincent, was the first naturalist who has described this singular 

 hydrophite, in the Diet, classique a" Histoire Naturelle. He says of the Oscilla- 

 ria Pharaonis, " we are indebted to the learned Mougeot for a knowledge of this 

 singular species, which, in February and March of the year 1825, presented on 

 the Lakes of Neufchatel and Morat, a phenomenon which recalled the idea of one 

 of the plagues of Egypt, by which the waters were changed into blood. De Can- 

 dolle published some account of this Oscillaria, proposing to call it Oscillaria 

 purpurea — a name which would have created considerable confusion, since other 

 Oscillaria possess a purple colour. The present species is not itself coloured ; but 

 possesses the property of giving out a coloured matter. Its filaments, whose 

 structure has not yet been examined under a microscope, are excessively fine, at 

 first invisible to the naked eye, but become visible by a careful separation in fluid, 

 when they resemble minute undulated tufts, similar to those of the Orgyrosa, to 

 which, also, the Pharaonis we examined presents another resemblance, that of 

 being curled and shining, though the colour is quite different. A red tinge is given 

 by it to paper. It appears that this Oscillaria, while living, was of a fine red 

 colour, which, on dessication, passed into shades of lilac, more or less distinct." 

 De Bribisson remarks that the above description would lead us to imagine that 

 the Oscillaria found in France was of a different species, if it were not that St. 

 Vincent had given it from a dried specimen. 



This Oscillaria is not of a red colour ; its filaments are extremely delicate, 

 being scarcely the hundredth part of a millimeter in diameter. They are long, of 

 a shining blackish -green colour, often as if fasciculated ; growing from a mucous 

 base, thick, and yellowish. It grows in considerable tufts, sometimes more than 



