FISHES. 363 



nerativc organs, and these are in their turn controlled by 

 the temperature of the water in which the fishes remain, or 

 the supply of food. In rivers where salmon spawn, it is 

 observed that they continue entering the river for the space 

 of seven or eight months. Those marine fishes, such as the 

 herring, pilchard, and many others, which leave the deep- 

 water, and approach the shores for the purposes of spawn- 

 ing, are equally irregular, with respect to their periods of 

 appearing and disappearing. 



Besides these movements, which depend on the generative 

 impulse, many marine fishes appear to migrate from one shore 

 to another, influenced bylaws which have never been satisfac- 

 torily explained. Thus, haddocks have been known to visit a 

 coast for many years in succession, and then suddenly to dis- 

 appear, leading off at the same time all those predacious fish 

 which fed upon them. Perhaps these movements may de- 

 pend upon the supply of food, and be regulated by circum- 

 stances over which we can exercise no controul. . Accurate 

 observations, however, would probably ascertain the limits 

 of these migrations, and enable us to derive advantage from 

 motions which at present we regard as calamitous. 



In tracing the history of those attempts which have been 

 made to subject this portion of the creation to our controul, we 

 trace at the same time the progress of civilization and luxury. 

 In Egypt, the inhabitants had their sluices and their fish- 

 ponds in the days of Isaiah (chap. xix. 10.), and from this 

 early seat of the arts and sciences, the Romans probably ac- 

 quired the knowledge of rearing and feeding fish. During 

 the more prosperous days of that refined people, almost every 

 wealthy citizen had his fish-ponds. In modern times, the 

 Chinese bestow more attention on the cultivation of fish, 

 than perhaps any other nation. And in Europe, the im- 

 portance -of the subject has been duly appreciated by the 

 Swedes, Prussians, and Germans. In the latter countries, 



