In the case of the young queen-larva, however, a very different policy is instituted from the beginning. Not only is she given nursery-quarters allowing every facility for growth, but she is loaded with a specially rich kind of food night and day, until she actually swims in it. The nurse-bees are constantly pouring this glistening white substance into the cell for the whole five days of her larval existence, and the effect of this generous diet is obvious from the first in her more rapid growth, as compared with the worker-bee. A further advantage still is that the young queen has perfectly free access to the air at all stages of her development. The worker-cell is but sparsely ventilated, and that only through the narrow top, all its six sides and base being absolutely impervious. But the cradle-cell of the queen is not only made of a porous material throughout, but it is commonly placed at the edge of the comb, where it stand out in the full current of ventilation, the air percolating the whole substance of its walls in addition to entering freely at the large cell-mouth. Thus the main cause of the extraordinary difference in the development of the queen-bee and the worker is that of treatment; the one being given unlimited rich food and oxygen and room to grow in, the other receiving only meagre workhouse diet, restricted quarters, and little air to breathe. Yet, making every allowance for the stimulating or retarding effect of these agencies on the young female grub, we are still hardly any nearer to solution of the mystery. We are compelled to believe that the egg which produces the worker is identical in its nature with that from which is evolved the queen-bee, because a simple experiment will at once dispel all doubt on the matter. If the egg deposited in the queen-cell be removed and an egg taken from any one of the thousand of worker-cells in a hive be put in its place, the worker-egg will always produce a fully developed and accoutred queen-bee. On the other hand, if an egg be taken from a queen-cell and placed in a worker-cell, it will as infallibly hatch out into a common undersized worker. It would be sufficient tax on the credibility if the differences of queen and worker were only those of degree. If the queen were nothing but a large-sized worker-bee, in whom certain organs—which were atrophied in the worker—had received their full development, it would be a fact within comprehension; but the queen differs from the worker not only in size and the capability of her organism, but also on several important points of structure. And how can mere food and air and circumstance produce structural change? The worker has many bodily appliances, special members ingeniously adapted to her daily tasks, of which the queen is wholly destitute; while the physical organism of the queen varies from that of the worker in several important degrees.