i893. 



EVOLUTION IN THE GUIANA FOREST. 43 



caterpillar or other is, however, almost always found to digest the most 

 repellent juices and make all such efforts fruitless. A few have attained 

 a large measure of success on account of the toughness of their leaves 

 and their covering of stiff bristles or thorns ; but the most curious 

 provision is, perhaps, that by which a garrison of carnivorous ants is 

 accommodated. Either in swollen petioles or bases of thorns the ants 

 take up their abode and fall upon and destroy every invader. 



It is generally found that the trees most commonly attacked by 

 larvae are those the flowers of which are nectariferous, and therefore 

 provide food for the perfect insect. The fiddle-wood tree {Citharexylon) 

 is a striking example of this. Its spikes of white flowers perfume 

 the air at night for long distances, and attract large numbers of moths. 

 These same insects lay their eggs upon the tree, with the result that 

 myriads of larvae are produced, and the tree is often denuded of every 

 leaf. In the ordinary course of nature it drops its leaves and is bare 

 for a few days, after which the flowers are produced. The result of 

 the ravages of the larvae, like that of a ruthless pruning, is similar, so 

 that by the time the perfect moth emerges from its pupa-case the 

 flowers are ready to provide nectar for it. Other trees are attacked 

 in the same way, and careful observation will no doubt show that 

 there is something so remarkable in the actions of both plant and 

 insect that nothing short of design can account for it. 



Plants are undoubtedly improved by having to contend with so 

 many difficulties. The survivor is always the fittest and most suited 

 to the environment. One contrivance after another is developed, with 

 good, bad, or indifferent results, but generally somewhat to its advan- 

 tage in over-reaching its neighbours. Meanw^hile, however, its rivals 

 have not been sleeping, but as fast as the one gains an advantage 

 others will have put on some defensive armour, or perhaps become 

 more fitted to assume the aggressive. The study of the innumerable 

 contrivances by which the plants of Guiana have attained their 

 present stage is a never-ending source of interest. Probably there is 

 more to be learnt here in a few miles of forest, river, and swamp, than 

 in the whole of Europe, while the difficulties of a thorough investigation 

 of even one square mile are enormous. 



In Europe a large number of trees are anemophilous, but here 

 all are fertilised by insect agency. This is one of the reasons why 

 insects are so plentiful. At some seasons great moths fly into our 

 open rooms at night, often to fall a prey to the gas lights. Some- 

 times a table below the chandelier becomes littered with hundreds 

 of small moths and other insects in an hour or two. If a tree is 

 flowering outside, and happens to be one of those that are fertilised 

 at night, the increase is most striking. The moths fly towards the 

 white flowers and are apparently attracted farther by the intenser 

 light of lamps. In the streets of Georgetown the arc electric 

 lamps also attract great numbers of insects, including some of the 

 largest moths, which may be seen wheeling round them almost like 



