154 OUTLINES OF ICHTHYOLOGY. 



tion (and, therefore, of temperature), die rapidly 

 on being taken out of the water, and have flesh 

 prone to quick decomposition, and vice versa. Two 

 better examples of these laws could not perhaps be 

 given than those of the Bleak, a surface-swimmer, 

 and the Tench, a ground-swimmer. Amongst sea- 

 fish, Mackerel, Salmon, and Herrings may be 

 quoted as instances of the former law, and Eels, 

 Flat Fish, and Skate, of its converse. 

 ' With a low standard of respiration, and tenacity 

 of life, is connected the extraordinary power exhi- 

 bited by some species of sustaining extremes of. 

 high and low temperature. The Gold fish lives 

 and thrives in water as high as 85° Fahr. Fishes 

 exist in the hot springs and baths of various coun- 

 tries, ranging from 113° to 120°; and in South 

 America Humboldt states that he saw fish thrown 

 up alive, and apparently in health, from the bottom 

 of a volcano, along with water and heated vapour 

 which raised the thermometer to 210°, or two 

 degrees below boiling point. On the other hand, 

 in parts of Europe and North America, Perch and 

 Eels, and several species of Carp, are not uncom- 

 monly frozen and thawed again, and even trans- 

 ported from place to place in a frozen state, with- 

 out injury to life. 



- Passing to the senses with which fish are en- 

 dowed, we come, as first in importance, to the 

 sense of Sight. The eyes of fish occupy entirely 



