ii EQUATORIAL VEGETATION 267 



the numbers of suitable insects are totally inadequate to the 

 fertilisation of the countless millions of forest trees over such 

 vast areas as the equatorial zone presents, and that, in con- 

 sequence, a large proportion of the species have become 

 adapted either for self-fertilisation, or for cross-fertilisation by 

 the agency of the wind. Were there not some such limita- 

 tion 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-fertilisa- 

 tion by insect agency. 



Concluding Remarks on Tropical Vegetation 

 In concluding this general sketch of the aspects of tropical 

 vegetation, we will attempt briefly to summarise 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 avail- 

 able 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 examination 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 general in 

 the forests of extra-tropical countries, is probably dependent 

 on the extreme equability and permanence of the climate. 

 Atmospheric conditions are much more important to the 

 growth of plants than any others. Their severest struggle 

 for existence is against climate. As we approach towards 



