222 BRITISH FLOWERING PLANTS chap. 



flower, while the stamens project straight in front, the 

 pistil is turned somewhat downwards ; moreover, it 

 projects beyond the anthers, so that self-fertilisation is 

 doubly precluded. The next day the appearance of the 

 flower is quite altered. If it has been, as usual, visited 

 by insects, the pollen is gone, and the stamens gradually 

 turn downwards, while the pistil rises and takes their 

 place. This change has generally taken place before the 

 evening (seven to eight). During the first night, there- 

 fore, an insect visitor would rub its breast against the 

 anthers, during the second against the stigma. Between 

 the two stages yet other changes take place. The tube 

 commences to arch itself, and the upper and under lip 

 to roll up, so that the flower becomes less conspicuous. 

 Nor is this all. The colour changes : having been white 

 internally and reddish outside, it becomes a clear 

 yellow. This change is completed before the second 

 evening, at which time, therefore, all the flowers of this 

 age are yellow. A change of colour takes place in several 

 other plants, as in Polemonium and Myosotis, and in a 

 Brazilian species of Lonicera there are even two changes, 

 so that the flower presents successively three difi'erent 

 colours. The advantage probably is that moths natu- 

 rally fly first to the more conspicuous flowers, thus 

 dusting themselves with pollen, and then passing on to 

 the others to deposit some of it on the stigma. But 

 this is not all. In the next stage the flowers become 

 darker, and finally dirty orange, the corolla rolls up still 

 more, and the scent ceases, so that the flower becomes less 

 conspicuous, and less and less attractive to insects. On 

 the other hand, Kerner and Warnstorf consider that in the 

 absence of insect visits the flowers fertilise themselves. 

 The production of honey is so considerable that the tube 

 is sometimes filled up half way, In such cases it is 

 accessible to humble bees with the longest probosces, 

 especially to Bombus hortorum. The feast is, however, 

 not arranged for them ; there is no convenient alighting 

 stage, and they waste time in clumsy struggles to get 

 at the honey. The true friends are hawkmoths — 



