GENERAL OBSERVATIONS. 59 



dependent on the supply of food in their river, and that in 

 its turn rests mainly upon two things, the rapidity of the 

 current and the general temperature of the water. A 

 shallow river rushing quickly over rock or gravel gathers 

 less nutrition for the fish and produces fewer aquatic plants 

 and molluscs than a slow stream trundling quietly along 

 over a soft muddy bottom. It is very common to hear old 

 Yorkshire anglers lament the decadence of the fishing and 

 the diminution in the size of fish since they were boys fifty 

 years ago: something of this probably belongs to one of those 

 fond hallucinations with which the rose-tinted spectacles 

 of Memory are apt to torment the lean and slipper'd pan- 

 taloon, as he looks lovingly back upon " the greenest spot 

 on Memory's waste ;" but at the same time it is obvious 

 that the modern system of drainage has undoubtedly 

 affected the rivers, and in all probability the fish. In old 

 days a very moderate " fresh " would keep the river full for 

 a week. Percolating through the natural channels in the 

 land, and gathering microscopic nutrition as it went, the 

 rain found its way gradually and slowly to the river ; but 

 in these days the downfall is carried off the land through 

 pipes, as quickly as possible, bringing a sudden fresh, which 

 falls just as suddenly. It is quite possible that as in this 

 way the supply of natural food has been diminished, so the 

 trout have been adversely affected as regards their natural 

 growth. 



Then again it must be remembered that almost all the 

 Northern streams have their rise on wild, cold moorlands, 

 high up bare hillsides, many of which approach 2000 feet 

 in height, and that snow is often lying deep in the ravines 

 and gullies up there as late as the middle of April. 

 Melting very gradually, the snow sends down to the rivers 

 a constant accession of cold water which retards the 

 growth of aquatic larvae and postpones the sprouting of 



