The food of most species consists partly of insects and partly of the honey extracted from flowers. In order to obtain its food from the deep recesses of flowers, it possesses a long delicate beak; in some birds straight, in others curved downwards, while some, again, have a double curve. These variations in form are undoubtedly to suit the particular flowers on which they feed. By means of the peculiar structure of its tongue, which is long, filamentous, and doubled nearly to the base, it is enabled to project it to a great distance--even into the very depths of the largest flowers. There are upwards of three hundred species of these beautiful birds, and others are being constantly discovered--one vying with the other in beauty and richness of plumage--truly described as the "feathered gems of the mountain and forest." Some humming-birds tower, like the lark, to a great height in the air; while others keep always near the ground, among the shrubs in which they live. The nests of humming-birds vary in form and structure, but they are all of a most delicate nature. The external parts of some are formed of light grey lichen, and so perfectly arranged round it as to appear at a little distance as if only forming part of the branch to which it is attached. The interior consists of the silky fibres of the cotton-tree, extremely delicate and soft. The female lays a couple of eggs only, purely white, and about the size of peas. Ten days are required for their hatching, and the birds raise two broods in a season. When first hatched they are not larger than an ordinary-sized fly. Small as is the male humming-bird, he is a brave little fellow, and will courageously fly at the largest bird which approaches his nest; while, by the rapidity of his flight, he can avoid the attacks of even the swiftest of the larger race. There is a remarkable circumstance connected with humming-birds, especially in lofty regions, where they are more particularly susceptible of electric influences. It is well known that in many regions small birds are found killed after a thunder-storm, in consequence of the amount of electricity in the air. The humming-birds, as if conscious of this danger, build their nests of peculiar form, and of materials which are bad conductors of electricity, within which they are thoroughly protected. The nests of some are shaped like inverted cones, tapering to a fine point--that, as is supposed, the electricity which would destroy the delicate young ones, or the vitality of the eggs, may pass off into the air. Their notes are very feeble, rarely rising into a whistle. In one week after they are hatched, the young birds are ready to fly, but they are fed by their parents for nearly another week. Their plumage, however, does not attain its full brilliancy till the succeeding spring. But we must confine ourselves to the humming-birds of the Cordilleras, on the western coast. SWORD-BILL HUMMING-BIRD.