An elegant tree, allied to the last, the Holquahuitl of the Mexicans, or Ule di Papantla of the Spaniards (Castilloa elastica Deppe), furnishes the caoutchouc of New Spain, and the inconceivable quantities of this substance which are brought to our ports from the East Indies are collected in great part from the venerable fig-trees in which that Asiatic tropical world is so rich. On a trunk of giant girth, but seldom more than fifteen feet high, rests the enormous crown of the banyan, or holy fig (Ficus religiosa); the branches often run a hundred feet horizontally out from the trunk, sending down to the ground, at various intervals, long straight roots, which quickly penetrate and take firm hold, thus becoming props to the long branches. These wonderful trees, each one resembling a small wood, are dedicated to the god Fo, and the helpless, lazy Bonze builds his hut, not unlike a bird-cage, in its branches, in which he passes the day, sometimes asleep, sometimes dreaming in contemplative indolence in the pleasant cool shade. These great fig-trees (Ficus religiosa, indica, benjaminea, elastica) have sweet fruits, and their milk-sap contains the interesting caoutchouc. Some of these plants also yield a harmless juice. By far the most remarkable in this respect is the Palo de Vacca or Arbol de Leche, the cow-tree of South America (Galactodendron utile), which was first made known to us by Alexander von Humboldt. When a tolerably large incision is made into the trunk of this tree, a white, oily, fragrant, and sweet fluid, very similar to animal milk, flows out in sufficient quantity to refresh and satisfy the hunger of several persons. A striking contrast to this is afforded by the properties of other nettle-plants. One is tempted to call them the serpents of the vegetable kingdom; and the parallel is not difficult to carry out. The similarity between the instruments with which both produce and poison their wounds is very remarkable. The snakes have in the front of the upper jaw two long, thin, somewhat curved teeth, which are perforated lengthwise by a minute canal, which opens in front at the sharp point. These teeth are not fixed firmly in the jaw like the others, but movable, like, but in a less degree, the claws of a cat. Beneath each tooth, in a cavity in the jaw, lies a little gland, in which the poison is prepared, and the excretory duct of this gland runs through the canal in the tooth, and opens at its apex. When the animal bites, the resistance of the bitten body pushes back the tooth, so that it presses upon the gland, which squeezes out of it the deadly fluid into the wound. If we examine, now, the hairs on the leaf of the nettle, we find a wonderful agreement. The stinging hair consists of a single cell, terminating above in a little knob. Below, it expands into a small sac, which contains the irritating juice.