116 
INTRODUCTION OF FOREIGN FISH. 
can we predict what it will be hereafter; but its action is not 
for that reason the less certain. 
Introduction and Breeding of Fish. 
The introduction and successful breeding of fish of foreign 
species appears to have been long practised in China and was 
not unknown to the Greeks and Homans. This art has been 
revived in modern times, but thus far without any important 
results, economical or physical, though there seems to be good 
reason to believe it may be employed with advantage on an 
extended scale. As in the case of plants, man has sometimes 
undesignedly introduced new species of aquatic animals into 
countries distant from their birthplace. The accidental escape 
of the Chinese goldfish from ponds where they were bred as a 
garden ornament, has peopled some European, and it is said 
American streams with this species. Canals of navigation and 
irrigation interchange the fish of lakes and rivers widely sepa¬ 
rated by natural barriers, as well as the plants which drop 
their seeds into the waters. The Erie Canal, as measured by 
its own channel, has a length of about three hundred and sixty 
miles, and it has ascending and descending locks in both direc¬ 
tions. By this route, the fresh-water fish of the Hudson and 
the Upper Lakes, and some of the indigenous vegetables of 
these respective basins, have intermixed, and the fauna and 
flora of the two regions have now more species common to 
both than before the canal was opened. Some accidental 
attraction not unfrequently induces fish to follow a vessel for 
days in succession, and they may thus be enticed into zones 
very distant from their native habitat. Several years ago, I 
was told at Constantinople, upon good authority, that a couple 
of fish, of a species wholly unknown to the natives, had just 
been taken in the Bosphorus. They were alleged to have fol¬ 
lowed an English ship from the Thames, and to have been fre¬ 
quently observed by the crew during the passage, but I was 
unable to learn their specific character. 
Many of the fish which pass the greater part of the year in 
