The attractions of the sea coast are undoubtedly greater by day than at night, especially in the summer season, when the excessive heat of the land is tempered by the cool sea breezes, and when life, both on the cliffs and among the rocks, is at its maximum. But the sea is grand at night, when its gentle ripples flicker in the silvery light of the full moon. No phenomenon of the sea, however, is more interesting than the beautiful phosphorescence to be observed on a dark summer’s night. At times the breaking ripples flash with a soft bluish light, and the water in the wake of a boat is illuminated by what appears to be liquid fire. The advancing ripples, as they embrace a standing rock, surround it with a ring of flame; while streaks and flashes alternately appear and disappear in the open water where there is apparently no disturbance of any kind. These effects are all produced by the agency of certain marine animals, some of which display a phosphorescent light over the whole surface of their bodies, while in others the light-giving power is restricted to certain organs or to certain well-defined areas of the body; and in some cases it even appears as if the creatures concerned have the power of ejecting from their bodies a phosphorescent fluid. It was once supposed that the phosphorescence of the sea was produced by only a few of the lower forms of life, but it is well known now that quite a large number of animals, belonging to widely different classes, play a part in this phenomenon. Many of these are minute creatures, hardly to be seen without the aid of some magnifying power, while others are of considerable size. Among the peculiar features of the phosphorescence of the sea are the suddenness with which it sometimes appears and disappears, and its very irregular variations both at different seasons and at different hours of the same night. On certain nights the sea is apparently full of living fire when, almost suddenly the light vanishes and hardly a trace of phosphorescence remains; while, on other occasions, the phenomenon is observed only on certain patches of water, the areas of which are so well defined that one passes suddenly from or into a luminous sea. The actual nature of the light and the manner in which it is produced are but ill understood, but the variations and fitfulness of its appearances can be to a certain extent conjectured from our knowledge of some of the animals that produce it.