By this method about 65 per cent, of the eggs are fecundated. After the eggs have remained in the water 20 minutes or half an hour, they should be carefully washed, when they are ready to be placed in the hatching trough. Another process, however, said to have been the discovery of Mr. Vrasski, a Russian, known as dry impregnation, has been introduced into this country within a year or two by Mr. George Shepard Page of New York. By this process, which consists in expressing the ova into a dry pan and bringing them in contact with the milt before the addition of water, an average of 96 per cent. is fecundated. This method has been extensively adopted by American fish culturists. During the process of hatching, the troughs should be examined with care, and any addled eggs, accumulation of sediment, or growth of fungus removed. The period of incubation varies with the temperature. At 37° it is 165 days; at 39°, 121; at 41°, 103; at 44°, 81; at 48°, 56; at 50°, 47; at 52°, 38; and at 54°, 32. When the trout are first hatched they have an umbilical sac, about three times the size of the body, which furnishes them sustenance for a period varying, with the temperature of the water in which they are hatched, from 77 days at 38 1/2° to 60 at 40 1/5°, 46 at 43 1/3o, and 30 at 50°. When the sac is absorbed they require food, which may consist of bonnyclabber, curd, fresh shad or herring roe, raw or boiled, the yolks of eggs boiled hard, coagulated blood, liver raw or boiled, etc., which should be grated or pulverized.

When they outgrow the hatching troughs, they are let into the nurseries, and should be furnished with sunlight. For the adult trout similar food will suffice, maggots bred in decaying meat being perhaps the most nutritious. One great advantage of artificial breeding consists in the large proportion of eggs and fry that are saved from destruction. In the natural state these are the prey of frogs, aquatic birds, various species of fish, and numerous water insects. Fecundated ova, after the first formation of the fish is seen, may be transported without injury, if packed in moist moss in glass jars or tin boxes admitting the air. At a temperature from 5° to 15° above freezing point, they may be kept packed for two weeks; and even after the lapse of six weeks they have been found uninjured. The fry and adult fish may be transported in barrels or smaller vessels, care being taken to change the water and have it properly oxygenated.-The spawn of salmon requires a somewhat longer period of incubation than that of trout in water of the same temperature. In Scotland from 100 to 130. days are occupied, while in spring water of a uniform temperature of 50° not more than 50 or 60 days would probably be required.

In the Canadian establishments, with river water of from 33° to 34°, the period is 170 to 180 days. The fry, as in the case of the trout, are provided with an umbilical sac, which they carry for about six weeks, after which they require food similar to that of the trout. In Scotland the fry are generally kept in ponds and artificially fed until they become smolts, when they are turned into the river. This system has been criticised by Mr. Buckland and others, who contend that better results will follow if the fry are turned into the stream as soon as the sac is absorbed. The same conclusion has been reached with respect to trout by the marquis de Folleville at his establishment near Rouen. A pond an acre in extent, with an average depth of 4 ft., has been found large enough for the nurture of 300,000 young salmon. Salmon ova have been kept in ice for 00 days, half of the frozen eggs being afterward hatched; and they have been transported from England to Australia, packed in moss and surrounded with ice, occupying about 80 days in the passage.

A portion of them were found to be sound upon arrival, and were subsequently hatched in Tasmania. But whether the attempt to stock the rivers of Australia with salmon has succeeded, remains to be determined.-The spawn of shad is hatched in 72 hours in water at a temperature of 78°, and in seven days when the temperature is 60°. The umbilical sac sustains the fry only about six days. The most successful hatching apparatus is a box patented by Seth Green with a bottom of wire gauze, sustained in the water by two float bars fastened to the sides at an angle with the top. This is anchored in the stream near the shore, in a gentle current which passes freely through the gauze and buoys up the eggs within. When hatched the fry are liberated in mid-stream, the young shad instinctively seeking the main current, where they are comparatively free from the small fish most likely to devour them. The eggs after life is observed in them have been kept at a low temperature for six days when packed in damp moss, but it is difficult to transport them for a long distance.

The spawn of both shad and salmon is obtained in much the same manner as that of trout.-The French government early gave its patronage to fish culture, and the barren waters of the country have been stocked with appropriate fish: the rivers with salmon, the brooks with trout, and the sluggish streams, lakes, and ponds with carp, perch, eels, and pike. The establishment at Huningen was erected under the patronage of the government through the exertions of Prof. Coste in 1852. The buildings form a square comprising at the sides two hatching galleries 65 yards long and 9 1/2 yards wide, containing tanks and egg boxes. The buildings and ponds cover 80 acres. The water is supplied from springs on the ground, from the Rhine, and from a small stream called the Augraben. The establishment does not in general breed fish except by way of experiment, the chief business being the collection and distribution of eggs, which are brought mostly from Switzerland and various parts of Germany, and embrace those of several species of trout, the Danube and Rhine salmon, and the ombre chevalier. The commonest fish is the fera, similar to the whitefish of the United States. The spawn collected from various sources is carefully tended until it is sent to some point in need of it.