As soon as the piscicultural system became known, it was rapidly extended over the whole continent of Europe, and the rivers of Germany were among the first to participate in the advantages of the artificial system. In particular may be noticed the efforts made to increase the supplies of the Danube salmon, a beautiful and excellent food-fish, with a body similar to the trout, but still more shapely and graceful, and which, if allowed time, is said to grow to an enormous size. The young salmon of the Danube are always of a darker colour than those a little older, but they become lighter in colour as they progress in years. The mouth of this fish is furnished with very strong teeth; its back is of a reddish grey, its sides and belly perfectly white; the fins are bluish white; the back and the upper part of both sides are slightly and irregularly speckled with black and roundish red spots. This fish is also very prolific. Professor Wimmer of Landshut, the authorities at Huningue mentioned, had frequently obtained as many as 40,000 eggs from a female specimen which weighed only eighteen pounds. Our own _Salmo salar_ is not so fecund, it being well understood that a thousand eggs per pound weight is about the average spawning power of the British salmon. The ova of the Danube salmon are hatched in half the time that our salmon eggs require for incubation—viz. in fifty-six days—while the young fry attain the weight of one pound in the first year; and by the third year, if well supplied with the requisite quantity of food, they will have attained a weight of four pounds. The divisions of growth, as compared with _Salmo salar_, are pretty nearly as follows:—That fish, curiously enough, may at the end of two years be eight pounds in weight, or it may not be half that number of ounces. One batch of a salmon hatching go to the sea at the end of the first year, and rapidly return as grilse, handsome four-pound fish, whilst the other moiety remain in the fresh water till the expiry of the second year from the time of birth, so that _they_ require about thirty months to become four-pound fish, by which time the first moiety are salmon of eight or ten pounds! These are ascertained facts. This is rapid work as compared with the Danube fish, which, after the first year, grows only at about the rate of eighteen ounces per annum. But even at that rate, fish-cultivation must pay well. Suppose that by the protected or piscicultural system a full third (_i.e._ 13,500) of the 40,000 eggs arrive in twelve months at the stage of pound fish, and are sold at the rate of threepence per pound weight, a revenue of £162 would thus result in one year’s time from a single pair of breeding salmon! Two pairs would, of course, double the amount, and so on.