The third pond (3) has a surface of about 5000 yards, with a depth equal to that of the second pond. An underground canal (G) runs along the eastern side, and at distances of 2 metres trenches lined with stones loosely thrown together join the canal to the basin, and allow the fish to circulate through these subterranean passages, where every stone becomes a means of shelter and concealment. The adult trout can conceal themselves in the submerged holes and crevices of the islands (F) of which there are three in the pond. The narrowest part of the basin is crossed by a viaduct of 8 metres (N), to the arch of which is fitted an iron grating with rods in grooves to receive either a sluice or a snare. The sluice, formed of fine wire, keeps out the fish that would destroy the spawn at the time of fecundation. The spawn is covered with a layer of fine round gravel, to the thickness of 0 m. 30, which the trout can easily raise as fast as it bursts the egg. The snare or netting encloses the fish destined for artificial breeding without hurting them, and also secures the fish that are to be consumed, and those which it is necessary to destroy because of their voracity, as the pike. A floodgate placed at the lower end of the pond permits the pond to be emptied when necessary, and an iron grating prevents the escape of the fish. All the ponds are protected by a double line of galvanised iron wire placed on posts armed with hooks, and yet low enough to allow a boat to pass. The water of the ponds finally passes into the Isere, where a permanent snare allows strange fish to penetrate into the ponds. At spawning time a great many trout deposit their spawn there. The small pond (4) fed by the mill-stream is a sort of reservoir for large fish destined for sale or domestic use. Throughout the year the fish caught in the nets of the third pond are placed in this basin, so when the spawning season arrives it is a vast nursery for the purpose of reproduction. In the house (O) built near the bridge (N) of the third pond lodge the guard and the hatching-apparatus. The _appareils_ are similar to those employed at the Collége de France and are supplied from a spring. One particular appareil, placed in a source of which the temperature never varies, is slightly different from the other models: it is simply zinc boxes pierced with very fine holes. This apparatus, which has been in use for three years, has given great satisfaction. It may be added that the establishment at Buisse can supply 40,000 or 50,000 young trout in the year at five centimes each, a result which is mainly due to the care and solicitude with which M. de Galbert has conducted his operations.