Observations on the microscopic alga which causes the discoloration of the sea in various parts of the world / by C. Collingwood.

  • Collingwood, Cuthbert, 1826-1908.
Date:
1868
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the microscopic alga which causes the discoloration of the sea in various parts of the world / by C. Collingwood. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    each its cell-form, as in the case of the Confervse just de- scribed, hut rapidly vanishing under my eyes in a smoke-like manner, until, at the expiration of five or six minutes, there was nothing left of the whole ball but a general granular and amorphous appearance. A species of Trichodesmium was met with by Dr. Hinds, H.M.S. Sulphur, in 1826, on the west coast of North America, and again, in 1837, near St. Salvador, and was referred by Mr. Berkeley to M. Montagne, who regarded it as a new species, and named it T. Hindsii. This species, he says, was like that of the Arabian Gulf (which has been called T. Ehrenbergii), of a fine red colour, and was farther remark- able for the strong musty odour which it gave out, and which deserved the name of olidum. But as I have, on the one hand, remarked that I have nowhere met with Trichodesmium of a red colour, but always of the same fulvous or dirty yellow, so also I must add that on no occasion have I observed any peculiar smell, even when it has been thickest, nor have I ever heard any one with more acute perception of odour than myself remark anything unusual of that nature. M. Ehrenberg, in the original article in Poggendorf’s Annalen,’ states that it was not a permanent phenomenon in the Red Sea, but having observed it three times, viz., on the 25th and 30th December, and 5th January, he suggests a periodicity. The appearance and disappearance of the Alga, other things remaining the same, seems to me to he more re- markable than its permanence would have been, but I have no reason to believe that it is in any way a periodic phenomenon in the China Sea, for at any day, on successive days, and at all seasons, I have observed it unchanged. Ehrenberg’s speci- mens, also, he relates, sank to the bottom of the glass during the night, rising again in the heat of the day. I never ob- served any phenomenon approaching to this. They always floated in the water for the most part, hut some few seemed to have greater specific gravity, and sunk to the bottom. In the ocean, I have observed the scum on the surface in early morning and at sunset; but in the cases of the sparkling appearance in the sea, the fasciculi hovered at various depths below the surface, although it was during the heat of a tropical day. Montagne appends to his exhaustive paper in the f Annales des Sciences’ a series of conclusions on what was known, and questions for further observation, most of which are referred to, and answered in, the present paper; but there still remains the curious fact that although three species are described, T. erythrceum, T. Ehrenbergii, and T. Hindsii,