266 TROPICAL NATURE 



leaves standing up like great candelabra. Sometimes the 

 ground is carpeted with large flowers, yellow, pink, or white, 

 that have fallen from some invisible tree-top above ; or the air 

 is filled with a delicious perfume, the source of which one seeks 

 around in vain, for the flowers that cause it are far overhead 

 out of sight, lost in the great overshadowing crown of verdure." 



Although, as has been shown elsewhere, it may be 

 doubted whether light directly produces floral colour, there 

 can be no doubt that it is essential to the growth of vegeta- 

 tion and to the full development of foliage and of flowers. 

 In the forests all trees, and shrubs, and creepers struggle 

 upwards to the light, there to expand their blossoms and 

 ripen their fruit. Hence, perhaps, the abundance of climbers 

 which make use of their more sturdy companions to reach 

 this necessary of vegetable life. Yet even on the upper 

 surface of the forest, fully exposed to the light and heat of 

 the tropical sun, there is no special development of coloured 

 flowers. When from some elevated point you can gaze down 

 upon an unbroken expanse of woody vegetation, it often 

 happens that not a single patch of bright colour can be dis- 

 cerned. At other times, and especially at the beginning of 

 the dry season, you may behold scattered at wide intervals 

 over the mottled-green surface a few masses of yellow, white, 

 pink, or more rarely of blue colour, indicating the position of 

 handsome flowering trees. 



The well-established relation between coloured flowers 

 and the need of insects to fertilise them may perhaps be con- 

 nected with the comparative scarcity of the former in the 

 equatorial forests. The various forms of life are linked to- 

 gether in such mutual dependence that no one can inordi- 

 nately increase without bringing about a corresponding increase 

 or diminution of other forms. The insects which are best 

 adapted to fertilise flowers cannot probably increase much 

 beyond definite limits, because in doing so they would lead to 

 a corresponding increase of insectivorous birds and other 

 animals which would keep them down. The chief fertilisers 

 bees and butterflies have enemies at every stage of their 

 growth, from the egg to the perfect insect, and their numbers 

 are, therefore, limited by causes quite independent of the 

 supply of vegetable food. It may, therefore, be the case that 



