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Show 332 DARWINISM OITAP. and oro-an with the enormous powers of increase possessed by pla.nt. ,0ha~e enabled them to become again and agai~ rea.djustod to each chano-e of condition as it occurred, rosultmg m that endless va,ri~ty, that marvellous complo~ity,_ and tha,t exqui ite colouring which excite our adm~ratwn m the realm. of flowers, and constitute them the perenmal charm and crowmng glory of nature. Flowers the Prod~tct of Insect Agency. In his Origin of Species, Mr. Darwin first . stat~d that flowers had been rendered conspicuous and beautiful m order to attract insects, adding : "Hence we may conclude that, if insects ha.d not been developed on the earth, our plants would not have been decked with beautiful flowers, but would have produced only such poor flowers as we see on our ~r, oak, nut, anJ ash trees, on grasses, docks, and nettles, wh10h arc all fertilised through the a,gency of the wind." The argument in favour of this view is now much stronger than when he wTotc; for not only ha,ve we renson to believe that most of th ~Rc wind-fertilised flowers are degraded forms of flowers whiCh have once been insect fertilised, but we have abundant evidence that whenever in ect ao·ency becomes comparatively ineffecti ve, the colours of the flo,~ers become less bright, their size aJl<l beauty diminish, till they are reduced to such small, grcm:i s ~ , inconspicuous flo·wers as those of the r~pture-wort (Hcrm.ana o-labra) the knoto-rass (Poly<Yonum aviCularc), or the clm: to- o ' 0 0 . gamic flowers of the violet. There is good reason to _behove, therefore, not only that flowers ha,ve been developed m or:ler to attract insects to aid in their fertilisation, but that, havmg been once produced, in however great profusion, if the insect races were all to become extinct, flowers (in the temporak zones at all events) would. soon dwindle away, and that ultimately all floral beauty would vani. h from the ~art~. \Ve cannot, therefore, deny the vast change whiCh msects h:wc produced upon the earth's surfa.ce, and which has boca thu · forcibly a,J1(l beautifully delineated by Mr. Grant Al~en : "vVhile man has only tilled a few level plams, a few great n ver valleys, a few peninsular mountain slopes, leaving the vas~ mas:-; of earth untouched by his hand, the insect has spread himself over every land in a thousand shapes, and has made the whole XI THE SPECIAL COLOURS OF PLANTS 333 ------------------------------ flower~ng creati.on subser~ient to his daily wa.nts. His buttercup, _his dandelion! and his meadow-sweet grow thick in every English field. I-lls thyme clothes the hillside; his heather PU:plcs t~e blea~<: gray moorland. High up among the alpine hmghts ~Is gentian .spreads its lakes of blue ; amid the snows of the Himala~as his rho~odend~·ons gleam with crimson light. Even the ways~dc pond yields him the white crowfoot and the arrow.head, whi~e the broad expanses of Brazilian streams arc beautified by his gorgeous water-lilies. The insect has thus turned the whole surface of the earth into a boundless flo ._ d h' h . . WCI gar on, w I? supplies him .from year to year with pollen or ~oney, and 1t~elf m turn gams perpetuation by the baits that It offers for h1s allurement." I Concluding Rema1'ks on Colmw in Nature. In the last four ~hapters I have1 endeavoured to give a general and. sys~ematiC, though necessarily condensed view of the part W~lCh lS p~aye~ by colour in the organic world. vV e have seen m what mfimtely varied ways the need of concealment has led to the modification of animal colours, whether among polar snows or sandy deserts, in tropical forests or in t~e aby~s~s of the ocean. We next find these general adaptatiOns givmg way to more specialised types of coloration b~ wh~ch ~a,ch s~ecies has become more and more harmoni:ecl Wit~ Its n~mecliate surroundings, till we reach the most cunou.sly _mmute resemblances to natural objects in the leaf and ~tiC~ msect~, and those which are so like flowers or moss or birds droppmgs that they deceive the acutest eye. "\Ve have ~earnt, further, that these varied forms of protective colourmg are far more numerous than has been usually . uspected, ~ecause, what appear to be very conspicuous colours or markm~s when the species is observed in a museum or in a menagene, are often highly protective when the creature i. seen und~r the natural conditions of its existence. From these vaned classes of facts it seems not improbable that fully one-half of the species in the animal kino·dom po ess colours which have been more or less adapted ~o secure for them concealment or protection. Passing onward we find the explanation of a distinct type 1 The Colott?' Sense, by Grant Allen, p. 95. |