326 VARIATION OF COLOUR IN WILD PLANTS. 



colour in plants, and which dispose their tints to arrange them- 

 selves in a determinate manner, are for the most part still very 

 obscure. We know that however diversified the tints of a 

 flower may be, yet there is, in reality, no actual intermixture 

 of colour ; each hue is pure, distinct in itself, and accurately 

 defined, although they frequently deliciously harmonize and 

 soften into one another : take, for instance, a petal of the 

 tulip, or the party-coloured ranunculus of our gardens, where 

 the distinctions of tint are beautifully seen. Here we should 

 find, on a minute examination, that their brilliant and varied 

 hues are owing to the deposition of a colouring matter on the 

 inside of the cellules, of which their tissue is composed. The 

 tissue, being colourless and transparent, allows the colouring 

 matter to shine through it, and produce the dazzling effect 

 we witness. It appears, however, now, to be pretty well as- 

 certained, from the researches of Macaire, that all the various 

 colours of flowers may, for the most part, be ascribed to dif- 

 ferent degrees of oxygenation of the chromule, or colouring 

 matter contained in the vesicles of which they are composed. 

 Why green should be the colour chiefly confined to the fo- 

 liage of plants, and various other colours to the petals, which 

 are constructed on precisely the same plan, seems not yet de- 

 termined. It is curious to observe, however, what a striking 

 tendency various parts, in the neighbourhood of the floral 

 leaves, have to clothe themselves also in " coats of many 

 colours." The calyx of the Fuchsia, for instance, is of a 

 bright scarlet, and the bracts of the Hydrangea are often 

 blue. The oxygenation of which we before spoke, appears 

 to be effected by the agency of solar light ; and it may be 

 stated as a general rule, that the brightness of colour in 

 plants is in the direct ratio of the amount of solar light to 

 which they are exposed. The changes of colour which the 

 leaves of different plants assume as autumn approaches ; — the 

 red dress, for example, in which the goddess of Botany, at 

 that period, clothes the pear, the vine, the sumach, and Vir- 

 ginian creeper ; — has been ascribed by Macaire to the same 

 oxydising effect already mentioned. 



Schubler and Funk divide the colours of flowers into two 

 classes, the Oxydised (Xanthic of De Candolle), and the 

 Disoxydised (Cyanic of De Candolle). The first, or Xanthic 

 class, has yellow for its type, and the flowers belonging to 

 this series are capable of passing into red or white, but, ac- 

 cording to those authors, never into blue. To this statement, 

 however, there are certainly some exceptions. Viola lutea, 

 for example, has been observed, both by myself and Mr. 

 Moore, of York, with yellow and purple, or wholly purple, 



