Oyster-beds are often valuable property, and they are rented by various companies.  Rules have been made for the preservation of oysters, and to allow of new beds being formed.  Oysters require nursing, and unless the beds were carefully preserved and reconstructed, they would disappear. The beds are level banks of no great depth, which are seldom or never uncovered by the tide.  The first important business, when preparing a bed on which the oyster may spawn, or spat, as it is called, is to sprinkle over it broken plates and pans and tiles, with empty shells and such like substances, to which the embryo oyster immediately attaches itself.  This broken stuff is called "skultch."  The oyster deposits its spawn in July; and a month afterwards the young oysters can be seen sticking fast to the skultch in confused clusters.  Here they remain for two or three years, until they become about the size of a shilling; they are then taken up and spread evenly over the surface.  After another year they are once more dredged up and scattered on the beds, where they are to remain until full-grown.  Seven years are required to bring an oyster to maturity; but many are dredged up and sold when only five years old.  The muddy shores of Essex are highly favourable to the breeding of oysters; and those are considered very fine which are dredged from the beds at the mouth of the river Colne.