INSECTS AND FOREST FLOWERS. 65 



the species have become adapted either for self-fertiliza- 

 tion or for cross-fertilization by the agency of the wind. 

 Were there not some such limitation as this, we should 

 expect that the continued struggle for existence among 

 the plants of the tropical forests would have led to the 

 acquisition, by a much larger proportion of them, of so 

 valuable a character as bright-coloured flowers, this being 

 almost a necessary preliminary to a participation in the 

 benefits which have been proved to arise from cross- 

 fertilization by insect agency. 



Concluding Remarks on Tropical Vegetation. In 

 concluding this general sketch of the aspect of tropical 

 vegetation we will attempt briefly to summarize its main 

 features. The primeval forests of the equatorial zone are 

 grand and overwhelming by their vastness, and by the 

 display of a force of development and vigour of growth 

 rarely or never witnessed in temperate climates. Among 

 their best distinguishing features are the variety of forms 

 and species which everywhere meet and grow side by side, 

 and the extent to which parasites, epiphytes, and creepers 

 fill up every available station with peculiar modes of life. 

 If the traveller notices a particular species and wishes to 

 find more like it, he may often turn his eyes in vain in 

 every direction. Trees of varied forms, dimensions, and 

 colours are around him, but he rarely sees any one of 

 them repeated. Time after time he goes towards a tree 

 which looks like the one 'he seeks, but a closer exami- 

 nation proves it to be distinct. He may at length, 

 perhaps, meet with a second specimen half a mile off, or 

 may fail altogether, till on another occasion he stumbles 

 on one by accident. 



The absence of the gregarious or social habit, so 



F 



