Red and purple are the favorite colors of the former, while nocturnal moths show a preference for white and pale flowers. Thus the carnation and campion (Lychnis diurna), which open by day, have dark tints in comparison with Lychnis respertina, which unfolds its petals toward evening. Almost scentless by day, this white nocturnal flower diffuses a delicious fragrance in the twilight. The evening primrose (Ænothera), which, however, has yellow petals, is another example of this class. But the most remarkable plant of this type is the night-flowering stock (Cereus). Its pale blossoms open about seven in the evening, emit puffs of odor from time to time, and close up again toward midnight; by morning the flowers are withered. It is impossible to doubt that we have in this instance a flower specialized for the visits of nocturnal moths. The reason why nocturnal flowers, like the honeysuckle and evening campion, have pale-colored petals is not far to seek. These pale hues can be more easily distinguished at night than the red or purple of Dianthus or Githago. Among lilies both diurnal and nocturnal flowers occur, and clearly indicate by their colors to which section of the Lepidoptera they are adapted. The Turk’s-cap lily, with its perianth of fiery scarlet, is a characteristic example of a diurnal flower adapted to butterflies which wander abroad in daytime. On the other hand, Lilium Martagon, an L. candidum, with their white bells, are nocturnal lilies fertilized by night-loving moths. Two flowers, unlike in their coloring, can hardly be equally attractive to the same visitors, even if they grow together on the same plant, as in the case of Arnebia; the presumption, therefore, is that its spotted and pale blossoms are adapted for different insects. Moreover, the stronger colors of the younger flowers correspond with those of the day-blooming class, while the paler tints of those in the second stage will render them more attractive to nocturnal moths; and this view is strongly confirmed by the fact that night-blooming flowers are never variegated, but have their petals uniformly devoid of markings. By night the dark spots tend, in this instance, to conceal the blossoms so much that, if these are to be converted into nocturnal flowers, the removal of the spots is absolutely necessary. We may therefore conclude with tolerable certainty that the flowers of Arnebia in their first stage are adapted to bees and diurnal Lepidoptera, while in their second condition they array themselves in paler hues to attract nocturnal moths.