320 The Living Plant 



regular open flowers are yellow or white, and visited by a great 

 variety of small insects, especially flies. Blue flowers, however, 

 are visited mostly by bees, and, as the Larkspur and Monkshood 

 well illustrate, possess in general a position of nectar, a compul- 

 sory mode of access thereto, and an arrangement of stamens and 

 stigmas such that bees can best of all insects get the nectar and 

 most surely carry the pollen. Red flowers, such as the Pinks, are 

 oftenest visited by Butterflies, whose probosces are long enough 

 to reach to the bottom of their slender tubes for the nectar which 

 is there inaccessible to the very much shorter probosces of Bees. 

 Again, white flowers, in highly specialized kinds like the Orchids, 

 are preferred by Moths, which are indeed the only insects possess- 

 ing probosces of a length sufficient to reach to the bottoms of the 

 unusually long nectariferous tubes. The reason of course why 

 the insects prefer the respective colors is because these have 

 come to be associated with a construction of flower from which 

 they can easily draw nectar, while that nectar is pretty sure to be 

 present because other kinds of insects are largely excluded. These 

 relations, as before, are not precise in detail, but operate as a 

 general principle; and, as a general principle, also, it is true that 

 insects, floral colors, and floral structure have evolved together in 

 harmonious correlation. 



While considering this subject of floral colors, I may here add 

 a number of miscellaneous matters of particular interest. Thus, 

 as to white color, it is found to distinguish most flowers that bloom 

 in the dusk of the evening, that being of course the one color 

 which is most conspicuous in darkness ; and such flowers commonly 

 exhibit the very long nectar-tubes and other constructional 

 features adapting them to the visits of moths, which are chiefly 

 night-flying in habit. This is the explanation of the peculiarities 

 of the Night-blooming Cereus, Nicotiana, and some Jessamines. 

 Quite a different aspect of floral conspicuousness is involved in 

 the brilliant coloration of flowers that grow in rather inhospitable 

 places, such as Arctic shores, Alpine heights, and desert wastes. 



