Page:Aspects of nature in different lands and different climates; with scientific elucidations (IA b29329668 0002).pdf/62

 *[Footnote: the water, but the present state of our knowledge does not permit us to receive this as a valid explanation. (Joh. Reinh. Forster's Bemerkungen auf seiner Reise um die Welt, 1783, S. 57; Le Gentil, Voyage dans les Mers de l'Inde, 1779, T. i. p. 685-698.)

Perhaps there are few natural subjects of observation which have been so long and so much debated as the luminosity of the waters of the sea. What we know with certainty on the subject may be reduced to the following simple facts. There are several luminous animals which, when alive, give out at pleasure a faint phosphoric light: this light is, in most instances, rather bluish, as in Nereis noctiluca, Medusa pelagica var. (Forskäl, Fauna Ægyptiaco-arabica, s. Descriptiones animalium quæ in itinere orientali observavit, 1775, p. 109), and in the Monophora noctiluca, discovered in Baudin's expedition, (Bory de St.-Vincent, Voyage dans les Iles des Mers d'Afrique, 1804, T. i. p. 107, pl. vi.) The luminous appearance of the sea is due partly to living animals, such as are spoken of above, and partly to organic fibres and membranes derived from the destruction of these living torch-bearers. The first of these causes is undoubtedly the most usual and most extensive. In proportion as travellers engaged in the investigation of natural phenomena have become more zealous in their researches, and more experienced in the use of excellent microscopes, we have seen in our zoological systems the groups of Mollusca and Infusoria, which become luminous either at pleasure or when excited by external stimulus, increase more and more.

The luminosity of the sea, so far as it is produced by]*