484 SIGNIFICANCE OF ANTHOCTANIN. 



Here another very remarkable phenomenon may be considered. If the 

 colourless and scaly rhizome ot" Dentaria bulbifera be dug out of the dark forest 

 soil, it appears beautifully white, as if carved out of ivory. If it is put in a glass 

 vessel which is filled up with water and placed in the sun, so that the rhizome is 

 illumined by the direct rays, the white scales in a very short time assume a slight 

 violet tint, and in a few days the whole of the scaly rhizome becomes coloured 

 a deep violet. The same thing happens with the rhizomes of several species of 

 Cuckoo-flower, Violet, Toothwort, &c., but in these it is a little longer before the 

 violet colour appears. The tissues brought from the darkness i'nto the bright light 

 try to neutralize the influence of the light which is injurious to certain substances, 

 and therefore anthocyauin must not be regarded Tiierely as an agent for protecting 

 chlorophyll alone, but other chemical compounds also. That a far wider 

 significance in the life of plants is also assigned to it will be demonstrated in the 

 following section. 



Very often anthocyanin only appears temporarily, when the transmission of 

 food substances occurs on a very large scale. When seeds are germinated, and 

 their reserve matei-ials are conducted into the rapidly sprouting seedlings, such 

 as those produced from the starchy seeds of polygonums, oraches, palms, grasses, 

 &c., anthocyanin regularly appears, while later on it partly or wholly vanishes. 

 When in spring the foliage-buds on subterranean root-stocks or branches begin 

 to develop, and the materials stored in the stem structures travel into the young 

 leaves, to be employed there in further construction, these leaves do not appear 

 green in most cases, but reddish-violet or reddish-brown in colour. As instances 

 of this may be mentioned the well-known Tree of Heaven {Ailanthus glandulosa), 

 Walnut (Juylans regia), Pistaeia (Pistacia Terebinthus), the Sumachs (Rhv^ 

 Cotinus and Rhus Typhinum), the Judas Tree {Cercis Siliquastrum), Berberi- 

 desB (Mahonia, Podophyllum, Epimedium), Ampelideee ( Vitis, Cissus, Ampelopsis), 

 the Trumpet Tree (Catalpa syringcefolia), the red-berried Elder (Sambucus 

 racemosa). Cherry (Prunun avium). Peony and Sea Lavender {Pceonia and 

 Statice), and Rhubarb and Dock (Rheum and Rumex). Later on, when the 

 transmission is eflected, when the foliage-leaves are developed and are able to 

 act independently, the green chlorophyll appears; the loaves become gi-een, 

 and the anthocyanin either vanishes entirely or remains only in those places 

 whei-e it is required as a protection to the chlorophyll, or for another important 

 purpose to be dealt with in the following section, viz. the transformation of light 

 into heat. 



In many plants, anthocyanin is again developed in great abundance when 

 the leaves are obliged to stop their activity for a time on account of the com- 

 mencing dryness of the soil, or still more, on account of cold and the consequent 

 delay of supplies of crude sap. In order to describe this formation of anthocyanin 

 and everything connected with it, it is necessary to go back a little, and to discuss, 

 first of all, the metabolism and transport of materials connected with the stoppage 

 of activity in the green leaves at the close of the vegetative period. These 



