RED PIGMENT OF FLOWERING PLANTS. 409 



Temporary Red Coloration. 



1. Young developing shoots: common in temperate 

 regions ; very characteristic of trees of hill country of 

 tropics. 



2. Autumn leaves during depletion. 



3. Grown green leaves during cold weather of spring 

 or autumn (red on light-exposed side). 



Temporary or Pe^nnaneiit. 



4. Stem, leaf-stalk and mid-rib becoming red in sunny 

 places, not in shade. 



5. Wounded or weak places of leaves and fruit (neigh- 

 bouring sound tissue often red), 



6. i\lpine plants. 



7. Plants of deep shade (specially within the tropics). 



Permanent. 



8. As a phenomenon of variation. 



From this summary it will be clear, how grave is the 

 difficulty of ascribing to anthocyan any single consistent 

 function, and how tempting it is to apply the neo-teleology 

 of adaptation to each case. The pursuit of this doctrine of 

 the obvious has been followed by none more keenly than 

 by Kerner (17), who supplies a significance for nearly all 

 the different occurrences of anthocyan. His statements, in 

 some cases supported by experiment, are as follows. To 

 the anthocyan occurring in the under side of leaves, e.g., 

 in Boating leaves and those of shady forests, and in the non- 

 chlorophyll containing parts of Alpine plants, he assigns 

 the function of a converter of light to heat, by which means 

 the metabolic processes of the plant may be conceived to be 

 facilitated: transpiration, for example, being augmented. In 

 seedlings, developing in spring or in cold weather, the 

 anthocyan appearing promiscuously in the leaf, but mainly 

 along the veins and on the leaf stalk, assists, according to 

 him, the translocation of carbohydrates by keeping back light 

 which he states to be inimical to this transport. Lastly, the 



