Environment and Adaptation 229 



nents of these views go too far in the other direc- 

 tion, and are quite as much in need of further con- 

 firmation. It may be safely asserted that any showy 

 flower is normally pollinated by insects, and there is, 

 moreover, no question that color is in some cases 

 directly an adaptation. The pale color of most 

 night-blooming flowers is an obvious adaptation, 

 making the flowers more conspicuous in the dark 

 or twilight, and it is equally evident that the strong 

 scent of many of these nocturnal flowers is also a 

 powerful lure to the insects visiting them. Some 

 of the nocturnal flowers, which are quite scentless 

 in the daytime, exhale a very strong perfume in 

 the evening. This is especially true in some of the 

 Nightshade family. The long-tubed flower of the 

 white petunia and the white-flowered tobacco, often 

 grown as an ornamental plant, flood the garden with 

 their strong perfume soon after sunset, and the 

 odor wafted from the big trumpets of the tree 

 Datura is almost overpowering. These tubular 

 nocturnal flowers are especialy frequented by the 

 great humming-bird moths, whose enormously long 

 tongues are especially fitted for probing their nec- 

 taries. 



While such showy flowers as the magnolias 

 and buttercups, which are normally insect polli- 

 nated, can, if necessary, pollinate themselves, this 

 is not the case in a great many flowers, which are 

 so constructed that cross-pollination is absolutely 

 necessary. Only a brief reference can be made to 



