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406 TROPICAL NATUREThe seeds of a particular species may be carried to anothercountry, may find there a suitable soil and climate, may growand produceflowers ;but if the insect which alone can fertiliseit should not inhabit that country, the plant cannot maintainitself, however frequently itmay be introduced or howevervigorously it may grow. Thus may probably be explainedthe poverty in flowering-plants and the great preponderanceof ferns that distinguishes many oceanic islands, as well asthe deficiencyof gaily -coloured flowers in others. NewZealand in is, proportion to its total number of floweringplants,exceedingly poor in handsome flowers, and it is correspondinglypoor in insects, especially in bees and butterflies,the two groups which so greatly aid in fertilisation. In boththese aspects it contrasts strongly with Southern Australiaand Tasmania in the same latitudes, where there is a profusionof gaily -coloured flowers and an exceeding rich insectfauna.Another case is presented by the Galapagos islands,which, though situated on the equator off the west coast ofSouth America, and with a tolerably luxuriant vegetation inthe damp mountain zone, yet produce hardly a single conspicuously-colouredflower; and this is correlated with, andno doubt dependent on, an extreme poverty of insect life, notone bee and only a single butterfly having been found there.Again, there is reason to believe that some portion of thelarge size and corresponding showiness of tropical flowers isdue to their being fertilised by very large insects and evenby birds. Tropical sphinx-moths often have their proboscesnine or ten inches long, and we find flowers whose tubes orspurs reach about the same length, while the giant bees, andthe numerous flower-sucking birds, aid in the fertilisation offlowers whose corollas or stamens are proportionately large.Recent Views as to direct Action of Light on the Colours ofFlowers and FruitsThe theory that the brilliant colours of flowers and fruitsare due to the direct action of light has been supported by arecent writer by examples taken from the arctic instead offrom the tropical flora. In the arctic regions vegetation isexcessively rapid during the short summer, and this is heldto be due to the continuous action of light throughout the