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ANT-THRUSHES AND BEETLES.
half I surveyed and levelled myself; and my almost daily walks up it familiarised me with every bush and fallen log by its side, and with every turn of the clear cool brook that came prattling down over the stones, soon at the machinery to lose its early purity, and be soiled in the ceaseless search for gold.
The sides of the valley rose steeply, and a fair view was obtained from the tramway in the centre over the shrubs and small trees on each side, so that the walk was not so hemmed in with foliage as is usual in the forest roads. Insects were plentiful by this path. In some parts brown tiger beetles ran or flew with great swiftness; in others, leaf-cutting ants in endless trains carried aloft their burdens of foliage, looking, as they marched along with the segments of leaves, held up vertically, like green butterflies, or a mimic representation of a moving Birnam wood. Sometimes the chirping of the ant-thrushes drew attention to where a great body of army-ants were foraging amongst the fallen branches, sending the spiders, cockroaches, and grasshoppers fleeing for their lives, only to fall victims to the surrounding birds. On the fallen branches and logs I obtained many longicorn beetles ; the woodcutters brought me many more, and from this valley were obtained some of the rarest and finest species in my collection. On the myrtle-like flowers of some of the shrubs, large green cockchafers were to be found during the dry season, and a bright green rosechafer was also common. I was surprised to find on two occasions a green and brown bug (Pentatoma punicea) sucking the juices from dead specimens of this species. The bug has weak limbs, and the beetle is more than twice its size and weight, and is very active, quickly taking wing; so that the only way in which it could be overcome that I can think of, is by the bug creeping up when it is sleeping, quietly introducing the point of its sharp proboscis between the rings of its body, and injecting some stupefying poison. In both instances that I witnessed, the bug was on a leaf up a shrub, with the bulky beetle hanging over suspended on its proboscis. Other species of bugs certainly inject poisonous fluids. One black and red species in the forest, if taken in the hand, would thrust its sharp proboscis into the skin, and produce a pain worse than the sting of a wasp. Amongst the bushes were always to be found the beautiful scarlet and black tanager (Rhamphocælus passerinii, Bp.), and more rarely another species (R. sanguinolentus, Less.). Along with these, a brownish-coloured bird, reddish on the breast and top of the head (Phoenicothraupis fusicauda, Cab.), flew sociably; whilst generally somewhere in the vicinity, as evening drew on, a brown hawk might be seen up some of the low trees, watching the thoughtless chirping birds, and ready to pounce down when opportunity offered. Higher up the valley more trees were left standing, and amongst these small flocks of other birds might often be found, one green with red head (Calliste lavinice, Cass.); another, shining green, with black head (Chlorophanes guatemalensis); and a third, beautiful black, blue, and yellow, with yellow head (Calliste larvata, Du Bus.). These and many others were certain to be found where the climbing Marcgravia nepenthoides expanded its curious flowers. The flowers of this lofty climber are disposed in a circle, hanging downwards, like an inverted candelabrum. From the centre of the circle of flowers is suspended a number Ch. VIII.] FLOWERS FERTILISED BY BIRDS.
of pitcher-like vessels, which, when the flowers expand, in February and March, are filled with a sweetish liquid. This liquid attracts insects, and the insects numerous insectivorous birds, including the species I have mentioned and many kinds of humming-birds. The flowers are so disposed, with the stamens hanging downwards, that the birds, to get at the pitchers, must brush against them, and thus convey the pollen from one plant to
FLOWER OF MARCGRAVIA NEPENTHOIDES.
another. A second species of Marcgravia that I found in the woods around Santo Domingo has the pitchers placed close to the pedicels of the flowers, so that the birds must approach them from above; and in this species the flowers are turned upwards, and the pollen is brushed off by the breasts of the birds. In temperate latitudes we find many flowers fertilised by insects, attracted by honey-bearing nectaries; and in tropical America not only bees, moths, and other large insects carry the pollen from one flower to another, but many flowers, like the Marcgravia, are specially adapted to secure the aid of small birds, particularly humming-birds, for this purpose. Amongst these, the “palosabre," a species of Erythrina, a small tree, bearing red flowers,
FLOWER OF PALOSABRE.
that grew in this valley, near the brook, often drew my attention. The tree blooms in February, and is at the time leafless, so that the large red flowers are seen from a great distance. Each flower consists of a single long, rather fleshy petal, doubled over, flattened, and closed, excepting a small opening on one edge, where the stamens protrude. Only minute insects can find access to the flower, which secretes at the base a honey-like fluid. Two long-billed humming-birds frequent it; one (Heliomaster pallidiceps, Gould), which I have already mentioned, is rather rare; the other (Phæthornis longirostris, De Latt.) might be seen at any time when the tree was in bloom, by watching near it for a few minutes. It is mottled brown above, pale below, and the two middle tail feathers are much longer than the others. The bill is very long and curved, enabling the bird easily to probe the long flower, and with its extensile cleft tongue pick up the minute insects from the bottom of the tube, where they are caught as if in a trap, their only way of exit being closed by the bill of the bird.
FOXGLOVE AND HUMBLE-BEE.
Whilst the bird is probing the flower, the pollen of the stamens is rubbed in to the lower part of its head, and thus carried from one flower to fecundate another. The bottom of the flower is covered externally with a thick, fleshy calyx-an effectual guard against the attempts of bees or wasps to break through to get at the honey. Humming-birds feed on minute insects, and the honey would only be wasted if larger ones could gain access to it, but in the flower of the palosabre this contingency is simply and completely guarded against.
Many flowers have contrivances for preventing useless insects from obtaining access to the nectaries. Amongst our English flowers there are scores of interesting examples, and I shall describe the fertilisation of one, the common foxglove, on account of the exceeding simplicity with which this object is effected, and to draw the attention of all lovers of nature to this other branch of a subject on which the labours of Darwin and other naturalists have of late years thrown a flood of light. The pollen of the foxglove (Digitalis purpurea) is carried from one flower to another by the humble-bee, who, far more than the hive bee, that "improves each shining hour,” deserves to be considered the type of steady, persevering industry. It improves not only the hours of sunshine, but those of cloud, and even rain ; and, long before the honey-bee has ventured from its door, is at work bustling from flower to flower, its steady hum changing to an importunate squeak as it rifles the blossoms of their sweets. The racemes of purple bells held up by the foxglove are methodically visited by it, commencing at the bottom flower, and ascending step by step to the highest. The four stamens and the pistil of the foxglove are laid closely