The royal cells may be obtained from any source, and artificially transferred to the divided frames, after which the frames must be placed in a stock hive for twenty-four hours for the bees to fix and repair the cells. Or, if more convenient, three or four such frames may be placed in the middle of a hive, and all stocked with eggs; the queen may be removed for a few hours, at the end of which a larger or smaller number of royal cells will be found to have been formed, and these in the middle frames, which should be the ones desired. The transferring process may still be needful, unless only one or two queens are wished for. The royal cells should be placed inside when the two parts of the frame are put together in the nucleus; there must however be only one such cell on each of these, as the first queen that is hatched will be certain to destroy the cells of the rest. Further mention of the subject of nucleus hives will be found under "Queen-Rearing." They should be constructed with narrow entrances so as to lessen the facilities to robber bees. § XVI. QUEEN-CAGES. These are small receptacles made of close wire or perforated zinc, just large enough to contain the queen with a few of her acknowledged subjects, and their use is on the occasion of her introduction to a new hive. The new queen is by this means protected from the primal hostility of the bees, but at the same time so much communication is permitted as suffices to familiarise them gradually with her presence. It is one of the characteristics of the bee nature that, however distressed they may be at the loss of their old queen, and however eagerly at work to produce a successor, they will not usually receive such at once from an artificial source. They will, however, supply her with food even when longing to transfix her with their stings.