FOOD OF FISH AND ITS PRODUCTION. 93 



Some rivers notoriously produce larger trout than 

 others, although the character of the soil they flow 

 through may to all appearance be very similar. I 

 will instance two, both of which are tributaries of 

 the Thames — ^the Chess, a branch of the Bucking- 

 hamshire Colne ; and the Wick, a little stream run- 

 ning through High Wycombe. I select these two 

 streams because they are only some ten or twelve 

 miles from each other, and because they are as 

 nearly as possible of a size. Now, it is generally 

 supposed that the very best and most fattening food 

 provided by Nature for the trout is the may-fly, or 

 green-drake. This fly abounds in profusion on the 

 Chess ; it is rarely if ever seen on the Wick — in fact, 

 it may be said not to exist there. The minnow, 

 likewise supposed to be most excellent and nourish- 

 ing food for the trout, is also a stranger to the Wick ; 

 or if it exists there, is not found in any considerable 

 number. Sticklebacks and millers' thumbs are found 

 in places, though they do not abound in all parts of 

 the stream. The caddis, or case grub of the smaller 

 flies, however, is very abundant ; and in some of the 

 hatch holes there are a considerable quantity of 

 leeches. 



On the Chess a trout of two pounds would be 

 a very fine one, the fish averaging from half a 



