CHAPTER IV 

 THE FRESH WATERS 



Variety of the Fresh Waters Similar Animals in widely separated 

 Places From Salt Water to Fresh Origin of Fresh-water 

 Animals Circulation of Matter in the Fresh Waters The 

 Web of Life in the Fresh Waters The Danger of Drought 

 The Danger of Frost The Danger of Flood Parental 

 Care among Fresh-water Animals The Story of the Eel 

 The Story of the Salmon The Story of the Lamprey 

 Water Insects The Story of the Fresh-water Spider. 



THE fresh waters do not occupy even a 

 hundredth part of the earth's surface 

 1,800,000 square miles out of the 197,000,000, 

 which form the total. But the haunt makes 

 up for its relatively small size by its great 

 variety. 



VARIETY OF THE FRESH WATERS 



There are lakes so vast that their depths 

 may be as cold, and dark, and plantless as 

 those of the sea itself. Lake Baikal in Asia 



has a depth of 760 fathoms, with an additional 



136 



