FISH IN DESERT REGIONS. 433 



The rivers again roll down, filling the dry watercourses 

 with a turbid flood, setting free the imprisoned fish to 

 rejoice once more in a renewed lease of life and 

 liberty thus furnishing us with another of those nu- 

 merous instances the student of nature meets with at 

 every turn (and nowhere more than in the Wilderness) 

 which teach us that however great may be the ap- 

 parent difficulties which Nature has to contend with, 

 there is no such word as " impossible " recognised in 

 her economy. Everything to her is not only possible, 

 but easy, and wherever a difficulty arises, means are 

 provided to cope with it. It is therefore impossible 

 for us to say where life may exist, seeing that it does 

 exist under the most apparently (to us) impossible 

 conditions. 



In the case of great rivers flowing through barren 

 deserts the difficulty is often bridged over in a dif- 

 ferent way. Intense heat and months of drought, 

 wherein not a drop of rain has fallen, may have to 

 a great extent dried up the beds of these rivers, but 

 as a rule deep pools are still to be found existing at 

 intervals along their courses, which have been exca- 

 vated by the powerful current during the rainy season 

 and form havens of refuge for their finny inhab- 

 itants. And there they are often to be found collected 

 together during the dry season, in incredible numbers, 

 sometimes furnishing the angler with splendid sport. 

 We shall give instances of this further on. 



It may also be well to say a few words upon the 

 subject of the broad shallow streams which are gene- 

 rally found in considerable numbers crossing the surface 

 of extensive plains, such as the great prairie region 

 of North America. 



VOL. ill. 28 



