20 THE COLOURS OF FLOWERS. 



pink, purple, or blue petals, they could not specially 

 favour and select them ; so that we are as yet hardly 

 nearer the solution of the problem than ever. 



Here Mr. Sorby, who has chemically studied the 

 colouring matter of leaves and flowers far more deeply 

 than any other invest'gator, supplies us with a useful 

 hint. He tells us that the various pigments of bright 

 petals are already contained in the ordinary tissues of 

 the plant, whose juices only need to be slightly 

 modified in chemical constitution in order to make 

 them into the blues, pinks, and purples with which we 

 are so familiar. "The coloured substances in the 

 petals," he says, " are in many cases exactly the same 

 as those in the foliage fron which chlorophyll has 

 disappeared ; so that the petals are often exactly like 

 leaves which have turned yellow and red in autumn, 

 or the very yellow or red leaves of early spring." " The 

 colour of many crimson, pink, and red flowers is due 

 to the development of substances belonging to the 

 erythrophyll group, and not unfrequently to exactly 

 the same kind as that so often found in leaves. The 

 facts seem to indicate that these various substances 

 may be due to an alteration of the normal constituents 

 of leaves. So far as I have been able to ascertain, 

 their development seems as if related to extra oxidi- 

 sation modified by light and other varying conditions 

 not yet understood.'* 



The different hues assumed by petals are all thus, 

 as it were, laid up beforehand in the tissues of the 

 plant, ready to be brougVt out at a moment's notice. 

 And all flowers, as we know, easily sport a little in 

 colour. But the question is, do their changes tend to 

 follow any regular and definite order } Is there any 



