In these days of oyster-farming the time at which the oyster becomes reproductive may be easily fixed, and it will no doubt be found to vary in different localities. At some places it becomes saleable—chiefly, however, for fattening—in the course of two years; at other places it is three or four years before it becomes a saleable commodity; but on the average it will be quite safe to assume that at four years the oyster is both ripe for sale and able for the reproduction of its kind. Let us hope that the breeders will take care to have at least one brood from each batch before they offer any for sale. Oyster-farmers should keep before them the folly of the salmon-fishers, who kill their grilse—_i.e._ the virgin fish—before they have an opportunity of perpetuating their race. Another point on which naturalists differ is as to the quantity of spawn from each oyster. Some enumerate the young by thousands, others by millions. It is certain enough that the number of young is prodigious—so great, in fact, as to prevent their all being contained in the parent shell at one time; but I do not believe that an oyster yields its young “in millions”—perhaps half a million is on the average the amount of spat which each oyster can “brew” in one season. I have examined oyster-spawn (taken direct from the oyster) by means of a powerful microscope, and find it to be a liquid of some little consistency, in which the young oysters, like the points of a hair, swim actively about, in great numbers, as many as a thousand having been counted in a very minute globule of spat. The spawn, as found floating on the water, is greenish in appearance, and each little splash may be likened to an oyster nebula, which resolves itself, when examined by a powerful glass, into a thousand distinct animals.