82 ANGLING. 



exist naturally in various baths and thermal springs, 

 of which the temperature ranges from 113 to 120 

 degrees ; and Humboldt and Bonpland were wit- 

 ness in South America to fishes being thrown up 

 alive, and apparently in good health, from the bot- 

 tom of a volcano, along with water and heated 

 vapour, which raised the thermometer to 210, that 

 is, to within two degrees of the boiling point. 

 Contrast this with Dr. Richardson's account of the 

 species of carp common in the fur countries of 

 North America. 



SECTION XV. 



The Swimming Bladder of Fishes. 



ONE of the most peculiar and characteristic organs 

 of the finny tribe is the swimming bladder, com- 

 monly so called. This is a fine pellucid often 

 silvery-coated viscus, of size and shape extremely 

 variable in the different kinds, and in many species 

 altogether wanting. In several genera, it has no 

 opening or canal of communication, and the air 

 which it contains must therefore be the result of 

 secretion. It is composed of an extremely fine in- 

 ternal tunic, and of another of a thicker texture, 

 and peculiar fibrous structure, remarkable for pro- 

 ducing the finest kind of isinglass. It is enclosed 

 within the general coating with which the perito- 

 neum invests the other viscera. It is sometimes 



