These establishments have been principally devoted to the hatching of the eggs of plaice.
Russia, justly offended, drew closer her ties with Prussia, where Bismarck was already hatching the plans which were to mature in 1866; and, if the attitude of Napoleon in the Polish question prevented any revival of the alliance of Tilsit, the goodwill of Russia was assured for France in the coming struggle with Austria in Italy.
In fresh-water culture little advantage, if any, has been found to result from artificial hatching, unless this is followed by a successful period of rearing.
As soon as ten or a dozen eggs are laid, the cock begins to brood, always taking his place on them at nightfall surrounded by the hens, while by day they relieve one another, more it would seem to guard their common treasure from jackals and small beasts of prey than directly to forward the process of hatching, for that is often left wholly to the sun.'
The hatching of eggs, whether of fresh-water or salt-water fishes, presents no serious difficulties, if suitable apparatus is employed; but the rearing of fry to an advanced stage, without serious losses, is less easy, and in the case of sea-fishes with pelagic eggs, the larvae of which are exceedingly small and tender, is still an unsolved problem, although recent work, carried out at the Plymouth laboratory of the Marine Biological Association, is at least promising.