n] FEATURES OF ENVIRONMENT 23 



Such a forest brings home to us what the struggle 

 for life really means and what it can do. Here it 

 is the struggle for sunlight and for rainwater and to 

 get them at first hand. One of the results is the 

 height of the trees, to which, so to speak, they have 

 forced each other, tall, often slender, branchless stems, 

 with an interlaced canopy above. A plant that can- 

 not grow tall by itself, climbs on to its neighbour's 

 shoulders. Even a cactus in a forest can climb like 

 ivy, and many of them have learned the trick so 

 successfully that they have been transformed into 

 epiphytes, either remaining still upright, or in the 

 guise of big, many-tailed pendent bunches. 



Such is the forest. Let us now consider the 

 inhabitants. The observation of animal life is most 

 disappointing to the novice. He may roam about 

 in this gloomy forest for hours and hear little and 

 certainly see less. Where are the two hundred 

 different kinds of mammals, birds, reptiles, and am- 

 phibians which we know to exist in a Mexican tropical 

 forest? Most of them inhabit the top storey, the 

 roof-garden which is formed by the tree-tops. Tf by 

 a lucky chance we obtain a bird's-eye view from a 

 precipice or from a river, we behold a different world. 

 A dense green carpet overstrewn with mauve, pink, 

 yellow or white flowers, visited by butterflies which 

 are preyed upon by lizards and tree-frogs, these being 

 in turn sought after by tree-snakes. Of bird life also 



