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FLOWER COLOURS.1

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FLOWER COLOURS. 1 CHANGES AND CONTRASTS. I Flower' are the most beau!iful objects in Nahirc. In form, colour, scents, and savours they are 3o varied that they cannot well be treated in a general manner to furnish anything in the shape of knowledge. The petals of flower; which come forward in an envelope of bructese or in the calyx, arc always more or less green, and possess the tints of the your? parts of ii e plant, though generally in a fault de- gree. when they are tirst perceptible; but aa they uru'old to- tin.- light they acquire all thoso hues vhicri make oar fields and gardens to gay. The distribution of the various colouring mat- ters of flowers in the cell. when the coloured tissue« are examined under the microscope, is seen to be much less regular tnan rmgnt bo imagined, and k doubtless one of the caus^ of tbeVcuiiar chromatic beauty of many flowers. SLfTTrom the solar beams it also been proved by experiment that theie i.-> a co.o li- able matter in the infusion of some plants, even *h™-<rb thev be perfectly colourless when ob- SSS an? upon that 'matter acicU W th. most decided primary effect. Phe action ot lio-h^ too re iders the colours of flowers m gene- ral more'brilliant, but it is not so necessary for producing them as it is for the peon m the [eaves indeed, when very richly coloured flowers are exoosed to the direct rays of the sun thoy become scalded, or otherwise injured. The colouring secretion 1 most universally di- ffused through "flowers i3 that termed chromuie, on which the colour of all green parts depends. It i-. found permeating the vetns, and its for- mation 33 due to the influence of light upon the tissues of the plant. It is further probable that all the colours of flowers are caused by the pre- sence of chromuie, altered by various chemical means. It is a curious circumstance, seemingly impossible of elucidation, that the flowers of a plant raised from seeds of the same parent in the* same soil often produce flowers of a differ- ent hue. Colour contrasts again occur in plants with flowers intended to catch the eye of flying and creeping food-searching animals and in- sects; others, which for obvious reasons are not brightly-coloured, nosscss intensely fragrant or obnoxious odours for servios in the same direc- tion. In writing upon the colours of plants, some reference must be made to the green of foliage. If the fully-developed leaves of a forest tree in summer sometimes tend towards a. certain heavi- ness and monotony of hue, there is still in this oaso a degree of variety present much depend- ing upon their positions on the tree. And then, too, the green colour of foliage varies with its age. To prove this there is no noces- eity to have recourse to prismatic analysis; one has only to illuminate both surfaoes with red light, or to inspect both througn a piece of red glass, to see a very striking difference, especial- ly noticeable with the yellowish-gre««n tollage of yetiig branches. Where plants are grown for ornamental purposes only, the coloration of the foliage and flowers are considered of pri. mary importance in their cultivation,vand yet how little do we know about this matter, in spite of all the attention that has been given to it. The colours peculiar to certain seasons of the year have been investigated, and wo know that "altitude has a marked effect on coloration. On the highest slopes of the Himalayas only blue flowers axe to be found. The fact is that though our knowledge is con- siderable of the results attained in the plant- world, we know but little regarding the pro- cesses by which they are brought about. The generally accepted view regarding all growth is that the formative processes are accomplished independently of any external influences, like light and electricity, heat, gravity, impact, fric- tion. and chemical action. These are stimuli which operate from outsido, but each speciea carries out the work in its own manner. The internal forces of the plant-body act in response to the stimuli, and the various working parts take up such relative position as enable them to carrying out their functions to the best ad- vantage. Each one acts in such a way 8.3 is best calculated to promote the interests (or the plant as a whole. In such a delicate machine it is evident that an unusual combination of exter- nal stimuli will have to be met by new exertions on the part of the plant to ensure the object 01 its existenoe-viz.. the production of its seed. The colours of flowers and fruits are due to the existence of pigments in their cells, either dissolved or in solid particles. The different Colours may originate from the varying colour of the cell-sap, or a different distribution of the cells containing coloured cell-sap, or from the different combinations of dissolved colouring mat- ter with the yellow, yellowish-red, or red ohro- moplasts and the green chloroplasts. White flowers do not get tneir colour from a pigment, but frr-,m the fact that certain oells are filled with air. Chief amongst the colouring pigments are chlorophyll and anthocyanin. The former is well-known, but anthocyanin is not so com- monly referred to as it ought to be. It is ow- ing to anthocyanin and the colours it assumes under varying conditions that the .shades of blue, red, violet, and black (the latter being probably a deep shacto of violet) appear in tho colours of flowers and leaves. Oxidation in cells containing blue anthocyanin changes pink convolvulus to deep purple as it matures, while borage also changes from pink to blue for same reason.—"Daily Telegraph."

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