PDF - Wallace Online

VITHE COLOURS OF PLANTS AND THE ORIGIN OFCOLOUR-SENSETHESource of Colouring Matter in Plants Protective Coloration and Mimicryin Plants Attractive Colours of Fruits Protective Colours ofFruits Attractive Colours of Flowers Attractive Odours in FlowersAttractive Grouping of Flowers Why Alpine Flowers are so beautifulWhyAllied Species of Flowers differ in size and beauty Absenceof Colour in Wind-fertilised Flowers The same Theory of Colourapplicable to Animals and Plantsand their GeographicalAction of LightRelation of the Colours of FlowersDistribution Recent Views as to Directon the Colours of Flowers and Fruits On the Originof the Colour-sense: Supposed increase of Colour-perception withinthe Historical Period Concluding Remarks on the Colour-sense.Source of Colouring Matter in PlantsTHE colouring of plants is neither so varied nor so complexas that of animals, and its explanation accordingly offersfewer difficulties. The colours of foliage are, comparatively,little varied, and can be traced in almost all cases to a specialpigment termed chlorophyll, to which is due the general greencolour of leaves ;but the recent investigations of Mr. Sorbyand others have shown that chlorophyll is not a simple greenpigment, but that it really consists of at least seven distinctsubstances, varying in colour from blue to yellow and orange.These differ in their proportions in the chlorophyll of differentplants ; they have different chemical reactions ; they aredifferently affected by light ;and they give distinct spectra.Mr. Sorby further states that scores of different colouringmatters are found in the leaves and flowers of plants, to someof which appropriate names have been given, as erythrophyll,which is red ;and phaiophyll, which is brown ; and many of