Page:Popular Science Monthly Volume 35.djvu/680

656 are curious. In some a portion of the body of the parent begins to grow out, and this continues until a perfect bud-like protuberance is the result, and then the bud drops off and, after various interesting changes, becomes a fully formed jelly-fish. Sometimes the parent begins to divide, and actually splits into two parts, each of which becomes a perfect animal.

So great is the transparency of most jelly-fishes that they are scarcely visible; but at night, what a change takes place! When a school is passed, the water becomes suddenly transformed to a mass of liquid fire, composed of individual balls that together, on account of their great number, appear as one vast sheet of light. When they are disturbed, their brilliancy is increased. Far different from the jelly-fish in structure, but resembling it in its phosphorescence, is Pyrosoma, a colony of animals often found in these warm waters, which together form a fleshy mass, possessing no remarkable points by day, but at night becoming most brilliantly phosphorescent. In the mass, six inches in length, there are hundreds of separate animals, each like the others, all massed together in a common colony. They are very curious, for, while most of the young remain to help build the mother colony, some become entirely separate, and, after swimming about for a while, begin a new cluster that soon takes the form of the parent group. Each group has a regular shape just like the original one. The same is true of corals and most other clusters formed of more than one individual.

In our surface towings we find many beautiful animals, but none have impressed me so strongly as the so-called sea-butterflies. They are small, usually, and seldom found in abundance, and, being thus inconspicuous, are not likely to be seen by those not specially searching for them. Every color is found in these beautiful forms, and, as they float upon the surface, with their wing like expansions spread out to catch the wind, but a small amount of imagination is needed to transform them into true butterflies accidentally fallen into the water. They have a very light and beautiful shell, with an air-chamber above to serve as a float, while from a lower compartment the wings are expanded. When startled, their sails are withdrawn into this chamber, and the oddly shaped shell is alone exposed to view. Sea-butterflies can, by arranging their sails so as to utilize the wind in the most effective manner, guide their course to a certain extent, just as the ship can proceed against a head wind. Their shells, which are often taken without the animal, present many very peculiar forms, from the nearly round to the long, sharply pointed ones, some with spines, others perfectly smooth; and we can see them in every conceivable color, the glassy, transparent kinds, the milk-white, and masses of the most brilliant colors, so confusing