218 FISH CULTURE food insures a rapid growth. The oysters for planting are obtained from the Atlantic coast, and chiefly along the shores of the Carolinas. They remain at the planting grounds from three to six months, and are then taken to market, many being again planted in the vicinity of New York and other cities. Artificial impreg- nation of fish eggs is said to have been dis- covered in the 14th century by Dom Pinchon, a French monk, who bred fish in wooden boxes having ends of wickerwork and the bot- toms covered with sand, in which the ova were deposited. The art seems to have been forgotten till 1758, when a memoir on the arti- ficial fecundation of the eggs of fishes, and on the stocking of rivers and ponds, by Jacobi, was published in German by Count Goldstein. It was translated into Latin, and was published in French in 1773, in the Traite general des peches of Duhamel du Monceau. The first attempts at the industrial use of this knowl- edge were made in Hanover. In 1837 Mr. Shaw, in Scotland, practised artificial impreg- nation for the purpose of restocking the streams with salmon ; and in 1841 Boccius, a civil en- gineer of Hammersmith, practised the art with trout on various estates. The following year Joseph Remy, a fisherman of La Bresse, in the Vosges, apparently without knowledge of the labors of others, resorted to artificial impreg- nation as an adjunct to his business, restocking the Moselle and other streams from which he gained his livelihood. His operations, brought to the knowledge of Prof. J. J. 0. Coste of the college de France in 1849, gave rise to the mod- ern industry of fish culture. The art has been practised chiefly with brook trout, salmon, shad, salmon trout, and whitefish. In breeding trout, it is usual to have a series of at least three ponds connected by raceways : the first for the young fish after they are taken from the hatch- ing trough or nursery, until they are 18 or 20 months old ; the second for the same fish for the next 12 months; and the third, from which they are taken for the table, for the same brood until they are 3 years old. As the last pond is vacated it is occupied by the younger fish from No. 2, and so on. An oblong pond is preferable to a circular one ; and if its width is one tenth of its length, it is more conve- nient for manipulation, and retains its cold- ness better, from the more rapid passage of the water through it. Young trout delight- ing in shallow water, the first pond should not be more than 6 in. deep at the upper and 2 ft. at the lower end. The bottom should be covered 2 or 3 in. deep with coarse gravel. The second pond, which should be from one third to one half longer and 2 or 3 ft. wider than the first, may have a more uniform depth, averaging 3 ft., and containing four or five times as much water. At the entrance to the raceway it should be of a good depth and free from gravel. The third pond should contain two or three times as much water as the second, having an average depth of 5 ft. They should be pro- vided with a flume at the bottom, for the pur- pose of draining them if required. The race- ways, which are the spawning places of the fish, should have a depth of 5 or 6 in., a width of from 2 to 3 ft., and a length of from 20 to 60 ft., according to the size of the ponds and the supply of water. The sides should be of board an inch thick and 12 in. wide, and, to fur- nish material for the trout to make their nests, the bottom should be covered with coarse gravel. The ends are closed with wire screens to keep the fish in the ponds allotted to them. The raceway should be so constructed that the water will flow through in a gentle current. The fish not spawning while in the first pond, a raceway is not necessary, but the water should be led in through two or more shallow rills from a foot to 2 or 3 ft. wide. A uni- formly low temperature of the water being re- ' quisite, and for hatching purposes clearness of stream, a deep spring is the best source of sup- ply. For hatching, the water should never be above 54 ; 46 or 47 is perhaps the most fa- vorable temperature. The latter part of Au- gust, about two months before the spawning season commences, is the proper time for trans- ferring the fish from one pond to another. In this country the hatching apparatus is usually a wooden trough, divided into compartments by transverse strips, by which the force of the current is broken, the water flowing gently over them. The bottom is covered to the depth of about an inch with clean gravel about the size of peas, the water, which must be filtered, being about an inch deep above. A supply which would fill a pipe an inch square, divided into four jets and flowing through as many troughs, is ordinarily used for 120,000 or 130,- 000 eggs. The hatching troughs should be en- closed, a house of rough boards being sufficient, which should be so arranged as to admit the light without sunshine. With the supply of water and for the number of eggs just men- tioned, the usual proportions are as follows : the filtering tank of strong plank extending at right angles across the upper ends of the troughs, 20 in. wide and 18 in. deep, admitting the water through two or three flannel screens ; the troughs, having a fall from the upper to the lower end of not more than an inch, from 12 to 16 ft. long, 10 to 14 in. wide, and 6 in. deep, divided into from 10 to 14 nests, the upper one being generally filled with gravel through which the water is again filtered ; the nurseries below the troughs, at least 16 in. deep, 20 in. wide, and 4 ft. long, so arranged that the water shall be 4 or 5 in. deep at the entrance from the troughs and only 2 in. deep at the outlet, and having their bottoms covered with gravel. At Hiiningen (Huningue), in Al- sace, the French adopted trays or troughs of earthenware, 25 in. long, 5 in. wide, and 4 in. deep, for hatching. The eggs are placed on grilles, formed of small parallel rods of glass arranged in a wooden frame resting on pro- jections on each side of the tray, a little be-
