COLOR 



183 



by the action of light, which is prevented by 

 the screening anthocyan. 



The demonstrations of the useful properties 

 of anthocyan as a developer of heat for pro- 

 moting the chemical processes are not nearly 

 so numerous. The opening of the flowers 

 of some of the alpine grasses is brought about 

 b\' the rapid elongation of the colored anthers 

 under the influence of sunlight. It is suggested 

 that the energy for the rapid growth is de- 

 rived from the sunlight by the coloring mat- 

 ter. It is quite true that the heat from any 

 source ^vill cause these flowers to open quickly. 

 The red color of certain gymnospermousflow^- 

 ers may accelerate their opening in the same 

 manner. 



The presence of layers of color in the lower 

 sides of rosettes, and in leaves and rapidly 

 growing organs in the deep recesses of jungles 

 and swamps, admits of no interpretation ex- 

 cept that such arrangements are useful in 

 promoting transpiration by means of the 

 heat developed. If a red and green leaf of the 

 same species are placed with their bases in 

 sunlight with the bases of the petioles placed 

 in calibrated cylinders full of water it will be 

 found that the transpiration is most rapid 

 from the colored leaf since it absorbs the 

 greatest amount of w^ater. A ver^' obvious 

 demonstration may also be made if the base 



Promotion of 

 metabolism 



Promotion of 

 transpiration 



