two cubic feet of the Bilin polishing slate. In the sea, gelatinous worms, living or dead, shine like stars,[5] and by their phosphoric light change the surface of the wide ocean into a sea of fire. Ineffaceable is the impression made on my mind by the calm nights of the torrid zone, on the waters of the Pacific. I still see the dark azure of the firmament, the constellation of the Ship near the zenith, and that of the Cross declining towards the horizon, shedding through the perfumed air their soft and planetary lustre; while bright furrows of flashing light marked the track of the dolphins through the midst of the foaming waves.
Not only the ocean, but also the waters of our marshes, hide from us an innumerable multitude of strange forms. The naked eye can with difficulty distinguish the Cyclidias, the Euglenes, and the host of Naids divisible by branches like the Lemna or Duckweed, of which they seek the shade. Other creatures inhabit receptacles where the light cannot penetrate, and an atmosphere variously composed, but differing from that which we breathe: such are the spotted Ascaris, which lives beneath the skin of the earthworm; the Leucophra, of a bright silvery colour, in the interior of the shore Naid; and a Pentastoma, which inhabits the large pulmonary cells of the rattlesnake of the tropics.[6] There are animalculæ in the blood of frogs and of salmon, and even, according to Nordmann, in the fluids of the eyes of fishes and in the gills of the Bleak. Thus the most hidden recesses of creation teem with life. We propose in these pages to direct our attention to the vegetable world, on the existence of which that of animals is dependent. Plants are inces-
