58 PHYSIOGNOMY OF PLANTS. magnetie lightnings), which, as the result of an increased tension in the interior of the globe, are announced for hours beforehand by the suddenly altered movements of the magnetie needle. (See my letter to the Editor of the Annalen der Physik und Chemie, Bd. xxxvii. 1836, S. 242-244).
Sometimes one cannot even with high magnifying powers discern any animaleules in the luminous water; and yet, whenever the wave strikes and breaks in foam against a hard body, a light is seen to flash. In such ease the eause of the phenomenon probably consists in the decaying animal fibres, which are disseminated in immense abun- danee throughout the body of water. If this luminous water is filtered through fine and closely woven cloths, these little fibres and membranes are separated in the shape of shining points. When we bathed at Cumana in the waters of the Gulf of Cariaeo, and afterwards lingered awhile on the solitary beach in the mild evening air without our clothes, parts of our bodies continued luminous from the shining organix particles which had adhered to the skin, and the light only became extinct at the end of some minutes. Considering the enormous quantity of animal life in all tropical seas, it is, perhaps, not surprising that the sea water should be luminous, even where no visible organie partieles can be detached from it. From the almost infinite subdivision of the masses of dead Dagysæ and Medusa, the sea may perhaps be looked on as a gelatinous fluid, which as such is luminous, distasteful to, and undrinkable by man, and capable of affording nourishment to many fish. If
