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Show 200 DARWINISM CHAP. assimilate with the black stripes of the tiger j and, in like manner, the spotty shadows of lca;cs in t~e forest so harmonise with the spots of ocelots, Jaguars, t1ger-cats, and spotted deer as to afford them a vc~-y perfect concealment. In some cases the concealment IS effected by colours arHl markings which arc so stri~in9 and peculiar that no ~nc '~h o had not seen the creature m Its native haunts would nnaglllc them to be protective. An example of this is aft:ordcd by the banded fruit pigeon of Timor, whose pure white head and neck, black wings and back, yellow ~clly, and deeply-curved black band across the breast, render 1t a very handsome and conspicuous bird. Yet this is what Mr. H: 0 .. Forbes s~yi'i of it : "On the trees the white-headed fnut p1gcon (Pt1lopm; cinctus) sate motionless during the heat of the day in munbcrs, on well-exposed branches; but it was with the utmost difficul ty that I or my sharp-eyed native servant could ever detect th em, even in trees where we knew they were sitting." I The trees referred to are species of Eucalyptus which abound in Timor. They have whitish or yellowish bark and very open folingr, and it is the intense sunlight casting black curved shadows of one branch upon another, with the white and yellow b:1rk and deep blue sky seen through openings of the foliage, that pro duces the peculiar combination of colours and shadow.- to which the colours am.l markings of this bird have become so closely assimilated. Even such brilliant and gorgeously coloured birds as the sun-birds of Africa arc, according to an excellent observer, often protectively coloured. Mrs. M. E. Barber rcmarl\s that "A casual observer would scarcely imagine that Lhc highly varnished and magnificently coloured plumngc of the various specie of N octarinca could be of servwc to them, ycL this is undoubtedly the case. The most unguarded moments of the li vc of these bi rcl · arc those that arc spent amongst the flower:, and it i. then thnt they arc less w:try than at <lilY other time. The different species of aloes, which blosson1 in succession, form the pri11cipal sources of their winter : upplies of food j and a legion of other gay flowering plants in spring and summer, the aloe blossoms especially, are all brillianLly coloured, a.nd they harmonise admirably with the gay plumage 1 A Naturalist's IVa,Lderinys in the Eastern Archipelago, p. 460. VIII ORIGIN AND USES OF COLOUR IN ANIMALS 201 of the different species of sun-birds. Even the keen eye of a hawk will fail to detect them, so closely do they resemble Lhc flowers they frequent. The sun-birds arc fully aware of this fact, for no sooner have they rclinq11i~hod the flowers than they become exceedingly wn.ry and rapid in flight, darting arrow] ike through the air and seldom remaining in exposed situations. Tho black sun-bird (N cctarinca amcthystina) is never absent from that magnificent forest-tree, the 'Kaffir Boom' (Erythrina caffra); all day long the cheerful notes of these birds may be heard amongst its spreading brunches, yet the general aspect of the tree, which consists of a huge mass of scarlet and purpleblack blossoms without a single green leaf, blends and hurmonises with the colours of the black sun-bird to such an extent that n. dozen of them may be feeding amongst its blossoms without being conspicuous, or even visible." 1 Some other cases will still further illustrate how the colours of even very conspie.uous animals may be adapted to their peculiar haunts. The late Mr. Swinhoe says of the Kerivoula picta, which he observed in Formosa : "The body of this bat was of an orange colour, but the wings were painted with orange-yellow and black It was caught suspended, head downward , on a cluster of the fruit of the longan tree (N ephelium longanum ). Now this tree is an evergreen, and all the year round some portion of its foliage is undergoing decay, the particular leaves being, in such a stage, partially orange and black This bat can, therefore, at all seasons suspend from its branches and elude its enemies by its resemblance to the leaves of the trcc." 2 Even more curious is the case of the sloths-defenceless animals which feed upon leave , and hang from the branches of trees with their back downwards. Most of the species have :t curious buff-colomed spot on the bn.ck, rounded or oval in shape and often with a darker border, which seem placed there on purpose to make th 'm conspicuous; and this was a great puzzle to naturalist., bcc:wse the long coa.rsc rrra.y or greenish hair was evidently like tree-moss and therefore protective. But an old writer, Baron von Slack, in his Voya9e 1 Trans. Phil. Soc. (?qf S. , t.frica), 1878, part iv. p. 27. 2 I'1'0IJ. Zuu{. Sue., 1862 p. 357. |