region, the nights in the tropics are made light by a curious, brilliant phenomenon: particularly bright sparks flash out in the ocean, at places where the waves break over rocky cliffs. Over one hundred kinds of animals may co-operate in producing this magic effect. Among these are the Salpœ, the life-history of which Chamisso learned on his voyage around the world. He was the first to prove that the Salpœ which cling together in chains do not vary at all from those swimming about singly. Other agents of a phosphorescent sea are the Medusœ (sea-nettles)—many-colored animals, possessing the most weird of forms. Some kinds have the shape of a bell; long filaments hang down from the edge, and in the center they have long arms to capture and paralyze their prey; in this they are aided by a number of those nettle-like organs mentioned in connection with the polyps.
Occasionally these queer creatures become visible on the surface, in masses several miles in extent. The material of which the body is composed seems to be chiefly water, as a medusa, about twenty pounds in weight, yielded when dried only thirty grammes of gelatinous flakes.
After the ominous sea-serpent, one of the most interesting of the beings which inhabit the mysterious depths of the ocean is Huxley's Bathybius, made of nothing but shapeless, motionless slime. It has been supposed to be the common origin of the animal and the vegetable kingdom, from which all beings have gradually been developed. But lately science has become doubtful as to its true properties, and has begun to question its organic nature; many naturalists consider it nothing more than gelatinous gypsum. Another animal, somewhat of this nature, which several years ago crossed the path of science, like a flickering will-o'-the-wisp, is the Eozoön Canadensis; gradually it has become more and more deprived of the animal characteristics once ascribed to it, and has been again assigned to the inorganic world.
Many are the errors and pitfalls that mark the path along which ever-searching Science strives onward to truth; and yet even these, in their way, show a triumph gained by the divine power of the human mind over its human failings!—(Abstracted from Virchow and Holtzendorffer's "Sammlung gemeinverständlicher wissenschaftlicher Vorträge.")
Professor Edward S. Holden has sketched in "The Overland Monthly" a plan for co-operative photography of the stars. Under ordinarily existing conditions of doing the work, it would take an observatory one hundred and forty years to make a complete photography of the heavens, or ten observatories fourteen years. The desirability of several observatories engaging in the work together is therefore obvious. Photography may be expected to help in the discovery of new asteroids; in the search for the hypothetical planet beyond Neptune; in making star-maps; in finding stars that make no impression on the eye or telescope; in accurately fixing the aspect of the sky, as it is for the benefit of students in all the future and for comparative astronomy; and for many other purposes of practical and scientific importance.
