26 THE WORLD'S WONDERS. 



in its decomposition as in its growth ; in no other zone are there 

 such destructive earthquakes and storms, nor does disease stalk 

 with such dreadful fatality in any other division of the earth. 

 Another characteristic of the tropics is found in the size and 

 ferociousness of its wild animals, whether beasts, birds, or rep- 

 tiles, which find their homes either in the deep jungles or on the 

 craggy peaks of great mountains, where the most intrepid hunter 

 cannot pursue them. But there are many other interesting 

 features found in the tropical zone which should be understood 

 before we proceed to a description of the animal life found within 

 its Km its. 



The lands lying within the tropics comprise a portion of 

 Mexico, all of Central America, and nearly all of South America, 

 Africa, the West India Islands, Polynesia, and about one-half of 

 Australia. The very great excess of water over land within the 

 tropics is one of the most important facts in physical geography, 

 for, were the proportions reversed, there would be a like reduc- 

 tion of growth and a corresponding amount of sterility ; without 

 water there can be neither vegetable nor animal life. All the 

 water that gushes up in fountains or swells into brooks and rivers 

 comes from the ocean, whence it is raised by evaporation and 

 carried along unseen channels of the air to be precipitated in the 

 form of rain or snow, sometimes thousands of miles distant from 

 ihe place whence it was drawn up. This water when first evapo- 

 rated has the salty taste of the ocean or, more directly speaking, 

 te strongly impregnated with salt, but as it is borne upward into 

 clouds, the vapor is subjected to an electrical influence not clearly 

 understood, but which decomposes the salt and precipitates the 

 vapor into pure water ; but in the descent it absorbs f rotai the air 

 a small quantity of carbonic acid, ammonia, or nitric acid, which 

 imparts to rain-water its peculiar taste. All water that is evapo- 

 rated and ascends into the clouds, of course does not come from 

 the ocean, as every fresh as well as salt body of water contributes 

 to that continual ascent and descent which nourishes the earth 

 and the fullness thereof. It has been computed by some patient 

 calculator that 200,000 cubic miles of water are raised each year 



