ON THE WATSONIA 



outright in a very short time were it not for the 

 transpiration of water from the pores of the leaf, 

 through which the temperature is equalized. 



In spite of this danger the sunlight is known 

 to be absolutely essential to the carrying on of life 

 processes, but it is obviously desirable to limit the 

 amount of heat as much as possible. 



So the question of the heating effect of the sun 

 must have a share in determining the color of the 

 floral envelope. 



A flower that blooms in the open and is exposed 

 to the blazing rays of the sun may advantageously 

 develop a glossy surface, just as a leaf does, in 

 order to reflect the largest possible amount of 

 light; and may in addition take on to advantage 

 such transformation of its tissues as will make 

 them reflect the long heat-bearing waves of the 

 spectrum. 



Such a flower, interpreted in ordinary lan- 

 guage, is red in color — for of course that is the 

 untechnical way of stating the facts that a given 

 object reflects the long rays of light, and absorbs 

 the others. 



Contrariwise, it would be almost fatal for a 

 blossom of ordinary texture to develop such con- 

 sistency as to absorb the main bulk of the light- 

 waves, inasmuch as such a blossom would soon be 

 heated to a dangerous temperature. That, doubt- 



[293] 



