APPENDIX. 235 



land, can for its size equal it in production ? What, then, 

 can be the particular food that fattens them so rapidly ? 



" My own impression is, that the fresh-water gammari, 

 or pulex, to which I have previously referred, have not a 

 little to do with it, for these insects abound in this stream 

 even to profusion to a greater extent, indeed, than I have 

 ever found them in any other brook. The trout feed upon 

 them voraciously j and it is a very common thing to find in 

 the trout a mass of these insects, half digested, and as large 

 as a filbert. I have seen the trout picking them off the 

 walls, which pen the stream in some places, as rapidly as a 

 child would pick blackberries from a hedge ; and I am in- 

 duced to think that this insect has, as I have said, much to 

 do with the fineness of the fish ; and the more so, because, 

 wherever I have found it to exist in any quantity, I have 

 invariably observed that the trout are of fine size, and in 

 unusually good condition.* 



* " These insects of course thrive better in sluggish than in rapid 

 water, though they do well enough in either when there are weeds. 

 They are peculiarly well adapted for lakes ; and were I owner of a 

 lake, I would leave no stone unturned to introduce them in large 

 numbers. They feed upon almost anything, and are the scavengers 

 of the water. They are very fond of the large fresh-water mussel, 

 and destroy and cat them in large numbers. These, which are 

 easily introduced, should be as food for the trout food. Where the 

 streams are too rapid for the plentiful production of the gammari, 

 it would be by no means a bad plan to make here and there (where 

 the situation of the soil and the banks suited such a plan) small 

 shallow ponds, supplied with water by means of a small pipe, and 

 having an exit to the stream. In these the requisite kind of weeds 

 might be planted, a stock of these little insects turned in, and some 

 kind of offal or other food occasionally being cast to them, and the 

 insects left to thrive and increase. They would of their own accord 

 miike their way into the stream, where they would afford excellent 

 food for the trout. Other kinds of insects might be also placed in 

 such food-breeding ponds, where they might propagate and multiply 



