“No. 2. November 15th. In another vessel, also furnished with Stratiotes, I placed six Argyronetræ (water-spiders). The one now referred to began to weave its beautiful web, about five o’clock in the afternoon. After much preliminary preparation it ascended to the surface, and obtained a bubble of air with which it immediately, and quickly, descended, and the bubble was disengaged from the body and left in connection with the web. As the nest was on one side, in contact with the glass, enclosed in an angle formed by two leaves of the Stratiotes, I could easily observe all its movements. Presently, it ascended again, and brought down another bubble, which was similarly deposited. In this way no less than fourteen journeys were performed, sometimes two or three very quickly one after another; at other times with a considerable interval between them, during which time the little animal was employed in extending and giving shape to the beautiful transparent bell, getting into it, pushing it out at one place, and amending it at another, and strengthening its attachments to the supports. At length it seemed to be satisfied with its dimensions, when it crept into it, and settled itself to rest, with the head downwards. The cell was now the size and nearly the form of half an acorn cut transversely, the smaller and rounded part being uppermost.... The manner,” continues Bell, “in which the spider possesses itself of the bubble of air is very curious, and, as far as I know, has never been exactly described. It ascends to the surface slowly, assisted by a thread attached to the leaf or other support, below, and to the surface of the water. As soon as it comes near the surface, it turns with the extremity of the abdomen upwards, and exposes a portion of the body to the air, for an instant, then with a jerk, it snatches, as it were, a bubble of air, which is not only attached to the hairs which cover the abdomen, but is held on by the two hinder legs, which are crossed at an acute angle, near their extremity, this crossing of the legs taking place the instant the bubble is seized. The little creature then descends more rapidly and regains its cell, always by the same route, turns the abdomen within it, and disengages the bubble.” To its home thus ingeniously constructed the water-spider brings whatever prey it catches. Here too it lays and arranges its eggs, which are in due time hatched, so that, though an air-breathing animal, it is both born and passes the earliest days of its life beneath the surface of the water—a curious apparent, though not a real, contradiction. CHAPTER XIV BEAVERS AND THEIR WORK—THE DAM AND THE POND—PRACTICE WITHOUT PRINCIPLES—A USEFUL TAIL—HOW BEAVERS CUT DOWN TREES.