180 AMERICAN FISH COLTUEE. 



margin of the Mississippi, througli its alluvial bottom lands, 

 by the occasional overflow of that river. This phenomenon 

 is strongly presented to the notice of observing anglers in 

 the neighborhood of St. Louis, and one is apt to wonder 

 where the great numbers and varieties of the perch family 

 come from, to stock those sluggish waters. In thinking 

 over the matter, I have fallen back on my favorite theory, 

 the instinctive migration of surplus production, as appli- 

 cable to fresh-water fishes, as well as to salt water or pelar 

 gian genera. 



" If the reader will take the trouble to look at a good 

 map, he will see that the states north and west of the con- 

 fluence of the Mississippi and Ohio, are threaded for thou- 

 sands of miles by rivers of gentle flow, and dotted with innu- 

 merable lakelets, which, to a great extent, are the feeders 

 and sources of the Mississippi. These are the breeding-places 

 of bass, crappie, and other percoids ; most of them spawn 

 early in the spring, soon after the ice has left the lakelets ; 

 and as most fresh-water species instinctively run down 

 stream after spawning, it is easily conjectured how large 

 schools of these fish are hurried along by freshets, and 

 deposited in the ponds that are fed by the overflow of the 

 great river. 



" After a rise in the Mississippi, the lakes and ponds 

 that skirt its course, above the mouth of the Ohio, and 

 down through the regions of cotton and sugar, are filled 

 with fish of this family. 



" In the ponds which have been replenished in this way 

 in the neighborhood of St. Louis, their numbers decrease 



