UP IN THE TREES. 193 



are occupied by dense rows of Tillandsias, which, 

 as it were, push everything else aside and take 

 possession of the upper surface. They can only 

 grow upright, as their vase-like circles of leaves 

 form reservoirs of water against the time when 

 little or no rain falls. Other plants have had to 

 store up moisture in many different ways, but this 

 is probably the simplest, and gives less trouble 

 than the building up of an assemblage of cells. 

 In the mountains similar reservoirs are utilised 

 by the beautiful Utricularia Humboldtii, as if they 

 were pools a striking example of the many shifts 

 and expedients of plant life to prevent a single 

 ray of sunlight being wasted. 



These are by no means all the epiphytes. 

 Hardly a twig is free from them unless the 

 gloom be too great. Fortunately most of them 

 have attained the power of living on very little 

 light, as certain others can exist and thrive in 

 places where we might expect them to be burnt 

 up. Yet, although these more delicate epiphytes 

 never see the sun, they differ much as to the 

 amount of light they require. On the boles of the 

 trees, often below the level of even ordinary floods, 

 grow patches of filmy ferns, the leaves in some 

 species overlapping each other and entirely cover- 

 ing the bark for several feet. A little higher 



