The first thing, probably, on which you will be inclined to ask questions, is the size of the fish in these streams. We have killed this morning four fish averaging a pound weight each. All below that weight we throw in, as is our rule here; but you may have remarked that none of them exceeded half a pound; that they were almost all about herring size. The smaller ones I believe to be year-old fish, hatched last spring twelvemonth; the pound fish two-year-olds. At what rate these last would have increased depends very much, I suspect, on their chance of food. The limit of life and growth in cold-blooded animals seems to depend very much on their amount of food. The boa, alligator, shark, pike, and I suppose the trout also, will live to a great age, and attain an enormous size, give them but range enough; and the only cause why there are trout of ten pounds and more in the Thames lashers, while one of four pounds is rare here, is simply that the Thames fish has more to eat. Here, were the fish not sufficiently thinned out every year by anglers, they would soon become large-headed, brown, and flabby, and cease to grow. Many a good stream has been spoilt in this way, when a squire has unwisely preferred quantity to quality of fish. And if it be not the quantity of feed, I know no clear reason why chalk and limestone trout should be so much larger and better flavoured than any others. The cause is not the greater swiftness of the streams; for (paradoxical as it may seem to many) a trout likes swift water no more than a pike does, except when spawning or cleaning afterwards. At those times his blood seems to require a very rapid oxygenation, and he goes to the ‘sharps’ to obtain it: but when he is feeding and fattening, the water cannot be too still for him. Streams which are rapid throughout never produce large fish; and a hand-long trout transferred from his native torrent to a still pond, will increase in size at a ten times faster rate. In chalk streams the largest fish are found oftener in the mill-heads than in the mill tails. It is a mistake, though a common one, to fancy that the giant trout of the Thames lashers lie in swift water. On the contrary, they lie in the very stillest spot of the whole pool, which is just under the hatches. There the rush of the water shoots over their heads, and they look up through it for every eatable which may be swept down. At night they run down to the fan of the pool, to hunt minnow round the shallows; but their home by day is the still deep; and their preference of the lasher pool to the quiet water above is due merely to the greater abundance of food. Chalk trout, then, are large not merely because the water is swift.