ON THE WATSONIA 



less, is why flowers that are even approximately 

 black are the rarest of all blossoms. 



On the other hand, a flower that reflects all the 

 rays of light, and hence that appears white in 

 color, is given protection against the heating influ- 

 ence of the sun even though it grows in the open. 

 When we add that white is a conspicuous color, 

 the extreme abundance of white flowers is suffi- 

 ciently accounted for. 



It is true that flowers that bloom in the shadow, 

 and particularly those that open in the twilight or 

 at night, are almost universally white, also, but 

 this is sufficiently explained by natural selection, 

 since white flowers are more conspicuous at night 

 than those of any other color. Moreover, it must 

 be recalled that white objects transmit heat less 

 readily than dark ones, so white is not a bad color 

 for a night blooming flower, inasmuch as it con- 

 serves the internal heat even if it is not called 

 upon to shut out heat from the sun's rays. 

 THE SEQUENCE OF COLOR DEVELOPMENT 



All this is more or less axiomatic, but the fur- 

 ther development of the theory of flower colora- 

 tion involves a certain amount of assumption, and 

 must be held only as a tentative theory. 



Briefly stated, the essentials of the theory are 

 that the original or earliest color of the flower was 

 green in imitation of the leaf. All the older or 



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