CHAPTER XIV 



TROUT WATERS AND CARP WATERS 



One thing follows upon another, and this chapter is 

 a natural sequel to the one that preceded it, since 

 both are concerned with respiration in the water, its 

 methods, and consequences. 



But this new question must be asked in a general 

 way if we are to get a clear and complete perspective 

 of it, and, in order to assure this, it is a good idea to 

 look at a map of physical geography, in which the 

 watercourses are shown with the contours of the sur- 

 rounding land areas. There we see in miniature, and 

 consequently more clearly, things as they actually are. 

 Graphic representation gives life to the whole. We 

 get a comprehensive idea of the places in which the 

 fishes dwell, the way they are formed, their relations 

 one to another, their resemblances and their contrasts. 

 So we grasp immediately the close relationship between 

 the natural conditions of soil and water with that of 

 the life they foster. 



The Loire, the great French river, gives us a good 

 example which we may take as a model for other 

 watercourses. Its basin, including the tributaries, 

 covers a total area of over 45,000 square miles. Its 

 course is 615 miles. It begins in the south in the 

 heights of Vivarais, about 5000 feet up, at the foot of 

 Mount Gerbier des Jones, not far from the Lake of 

 Issarles. Thence its waters flow directly northwards, 

 crossing the central plateau on one side, and come to 

 the Forez plain. This mountain torrent, narrow, swift, 

 often enclosed by a ravine, seems no more than any other 



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