44 COLIN CLOUT'S CALENDAR. 



or white. The bright hue thus assumed by young or 

 etiolated leaves is due to the oxidation of their materials ; 

 and, in most cases where growth takes place from a stock 

 of food already laid by, such oxidation must necessarily 

 go on. It is thus that we get the brilliant red, blue, and 

 yellow colouring of rhubarb, sea-kale, potato-sprouts, 

 beetroot leaves, growing paeonies, or young carrots, as 

 well as of long sprays in hedgerows and on young rose- 

 bushes. As soon as the leaves are fully expanded, the 

 green chlorophyll begins to develop, and they rapidly 

 assume their true hue and their active life ; but if they 

 are kept in the dark, or prevented from normally 

 developing, they go on retaining their original bright 

 colours for an indefinite period. 



It seems most probable that in all cases the oxidation 

 of green leaves, stems, or other parts of plants, produces 

 bright red, yellow, and orange colouring matter. We 

 are all familiar with this fact in the instance of autumn 

 hues, where Mr. Sorby has shown that the pigment is 

 chemically nothing more than an oxidised form of the 

 ordinary chlorophyll. So it is in the case of both flowers 

 and fruits, which are purely expensive structures, pro- 

 duced for the most part from reservoirs of raw material, 

 such as bulbs, tubers, starchy root-stocks, or permanent 

 stems, and thus exactly resembling the red or purple 

 shoots of the paeony, the rhubarb, the sea-kale, and the 

 hawthorn bushes. Every one knows that fruits are at 

 first green, and only grow coloured as they ripen that 

 is to say, as they oxidise. Mr. Sorby has shown that in 

 flowers, too, the colouring matter is at first green, and 

 exactly resembles that of ordinary leaves ; but as they 



