474 THE AMERICAN NATURALIST. [Vol. XXXVII. 



Conspicuousness Due to Insects. — Bright coloring in flowers, 

 usually accompanied by an enlargement of the perianth, has been 

 evolved through the agency of insects. Wind-flowers are small 

 and green or dull colored. " In New Zealand where insects are 

 so strikingly deficient in variety, the flora is almost as strikingly 

 deficient in gaily-colored blossoms." 1 In many genera as the 

 flowers become more conspicuous, there is an increase in the 

 number of visitors and the power of self-fertilization is lost. A 

 colored perianth, which contrasts strongly with the surrounding 

 green foliage, can evidently be more easily seen by both insects 

 and birds. For the same reason a contrast in color between 

 different species in blossom at the same time is advantageous. 

 Insects would be likely to make their visits indiscriminately in a 

 monochromatic Flora, as now happens in the case of similarly 

 colored species of buttercups and goldenrods. In the Alps, 

 where owing to the shortness of the summer all of the species 

 blossom at the same time, there is the greatest variety of colors. 

 It is a well known principle of physics that when a red and yel- 

 low card are placed side by side each appears more brilliant than 

 when viewed alone, that is the effect of bringing two colors not 

 complimentary in competition is to move them farther apart. 2 

 The utility of color contrast is sufficient to explain the evolution 

 of floral colors without recourse to the hypothesis that they afford 



Insects and Flowers. — The influence of insects upon the evo- 

 lution of flowers has undoubtedly been greatly overestimated. 

 There is certainly no satisfactory evidence that the ancestors of 

 all angiospermous flowers were once entomophilous, and that the 

 wind-fertilized forms are the result of degeneration. In my 

 opinion not only the principal plant series but many families and 

 genera were developed before the habit of flower visiting became 

 established. The formation of this habit must have required a 

 considerable interval of time. Neither is there sufficient evidence 

 to support the claim that the color of every flower has been 



