PASSING from Art to Nature, we have in the jaw of the serpent an exact type of the peculiar leverage by which the spear is thrown. If the reader will refer to the illustration, he will see that the lower jaw of the snake, instead of being set directly on the upper jaw, is attached to an elongated bone, which gives the additional leverage which is needful in the act of swallowing prey, after the manner of serpents. * * * * * IN War and in Peace we have been long accustomed to shield the edges and points of our sharp weapons with sheaths, and even the very savages have been driven to this device. I have in my collection a number of sheathed weapons from nearly all parts of the world, and it is a remarkable fact that the Fan tribe, who are themselves absolutely naked, sheathe their daggers and axes as carefully as we sheathe our swords and bayonets. In some points, indeed, they go beyond us; for the most ignorant Fan savage would never think of blunting the edge of his weapon by sheathing it in a metal scabbard. Their sheaths are beautifully made of two flat pieces of wood, just sufficiently hollowed to allow the blade to lie between them, and bound together with various substances. For example, the sheaths of one or two daggers in my possession are made of wood covered with snake-skin, while others are simply wood bound with a sort of rattan. Even the curious missile-axe which the Fan warrior uses with such power is covered with a sheath when not in actual use. [Illustration: PIERCING APPARATUS AND SHEATHS. SHEATHED SPEARS OF WAGANDA. GNAT. FLEA. BOMBYLIUS.] The figure on the right hand of the illustration represents the heads of two spears of Waganda warriors. When they present themselves before their king, the warriors must not appear without their weapons, and it would be contrary to all etiquette to show a bare blade except in action. The sheath can be slipped off in a moment, but there it is, and any man who dared to appear before his sovereign without his weapon, or with an unsheathed spear, would lose his life on the spot, so exact is the code of etiquette among these savages. The sheathed spears of Nature are shown in the same illustration. On the left is a side view of the piercing apparatus of the common Gnat. In the middle is the compound piercing apparatus of the common Flea, with which we are sometimes too well acquainted, the upper figure showing the lancets and sheaths together, and the lower exhibiting them when separated.