EVENING FLOWERS. 289 



tlie flowers in question are specially designed to 

 attract nip;lit-flyiiig moths. Their honey is usu- 

 ally concealed at the hottom of very deep straight 

 tubes, which only such moths can probe by unroll- 

 ing their long spiral proboscis ; and the heavy per- 

 fume is one particularly attractive to these ces- 

 thetic insects, which are thus enabled to discover 

 the hidden store of sweet nectar during the dusk 

 of evening. In the hours of sunshine, when the 

 proper moths are not flying about, the plant econ- 

 omizes its stock of scent by keeping the glands 

 which produce it tightly shut ; but, as soon as 

 twilight brings out its appointed visitors, it opens 

 them apace, and so advertises the neighborhood 

 of the attractive honey to its insect friends. 



For the self-same reason all or almost all the 

 night-llowering plants have snow-white blossoms. 

 In the gray dusk, blue and red and purple and 

 orange, which prove so attractive to the eyes of 

 bees during the glaring daytime, fade away alike 

 into dull inconspicuousness ; but pure white re- 

 flects whatever little light may still remain, and 

 so assists the perfume by catching the eyes of the 

 moths and leading them straight towards their 

 evening meal of scented honey. Nocturnal in- 

 sects, like nocturnal birds and bats, have organs 

 of vision specially adapted to the slender light of 

 evening, and so they can soon detect the small 

 white patches which mark out the flowers among 



