56 THE WORLD OF LIFE 



latitude. We could thus travel continuously for about five 

 thousand miles from Mexico to northern Argentina in an 

 almost unbroken tropical forest, or about the same distance 

 down the Amazon valley to Paranahyba in northern Brazil, 

 and then, after a break of a few hundred miles, along the 

 east coast forests for about two thousand miles more. This 

 probably equals, if it does not surpass, the tropical forest 

 area of the rest of the globe. 



We must also take into account the fact that, as a rule, 

 tropical forests differ from those of the temperate zone in 

 the species not being gregarious, but so intermingled 

 that adjacent trees are generally of distinct species, while 

 individuals of the same species are more or less widely 

 scattered. When, from some commanding elevation, we can 

 look over a great extent of such a forest, we can usually 

 see, at considerable intervals, a few, perhaps a dozen or more, 

 small patches of identical colour, each indicating a single 

 tree of some particular species which is then in flower. 

 A few days later we see a different colour, also thinly 

 scattered ; but in the region of the most luxuriant tropical 

 forests we never see miles of country thickly dotted with 

 one colour, as would often be the case if our European oaks 

 or beeches, birches or pines, produced bright-coloured flowers. 

 This fact would alone indicate that the tropical forests are 

 wonderfully productive in species of trees and woody 

 climbers, and hardly less so in shrubs of moderate size, 

 which either live under the shade of the loftier trees or line 

 the banks of every river, stream, or brooklet, or other 

 opening to which the sun can penetrate. In those latter 

 positions there is also no lack of herbaceous plants, so that 

 the whole flora is exceedingly rich, and the species composing 

 it rapidly change in response to the slightest change of 

 conditions. 



The difficulty of collecting and preserving plants in 

 these forest-clad areas is so great, and the number of resident 

 botanists who alone could adequately cope with the work is 

 comparatively so small, that it is not surprising to find that 

 the great forest region of tropical America is still very 

 imperfectly known. Only two considerable areas have been 

 systematically collected and studied — in North America 



