In the ocean, gelatinous sea-worms, living and dead, shine like luminous stars[75], converting by their phosphorescent light the green surface of the ocean into one vast sheet of fire. Indelible is the impression left on my mind by those calm tropical nights of the Pacific, where the constellation of Argo in its zenith, and the setting Southern Cross, pour their mild planetary light through the ethereal azure of the sky, while dolphins mark the foaming waves with their luminous furrows. But not alone the depths of ocean, the waters, too, of our own swamps and marshes, conceal innumerable worms of wonderful form. Almost indistinguishable by the eye are the Cyclidiæ, the Euglenes, and the host of Naiads divisible by branches like the _Lemna_ (Duckweed), whose leafy shade they seek. Surrounded by differently composed atmospheres, and deprived of light, the spotted Ascaris breathes in the skin of the earth-worm, the silvery and bright Leucophra exists in the body of the shore Nais, and a Pentastoma in the large pulmonary cells of the tropical rattle-snake[76]. There are animalcules in the blood of frogs and salmon, and even, according to Nordmann, in the fluid of the eyes of fishes, and in the gills of the bream. Thus are even the most hidden recesses of creation replete with life. We purpose in the following pages to consider the different families of plants, since on their existence entirely depends that of the animal creation. Incessantly are they occupied in organizing the raw material of the earth, assimilating by vital forces those elements which after a thousand metamorphoses become ennobled into active nervous tissue. The glance which we direct to the dissemination of vegetable forms, reveals to us the fulness of that animal life which they sustain and preserve.