and the idea reappears from time to time as a fact in natural history. There is so much that is legitimately wonderful in bee-arrangements that it is scarcely strange that some of the details given by ancient and mediæval naturalists in praise of their sagacity, and other estimable qualities, should overreach the possibilities, and fail in the not unimportant element of truth.[99] The sagacious cranes seem to have found several valuable uses for their pieces of rock. We are told that while the main body are resting at night, sentinels are posted to guard against surprise, so that the flock or covey, or whatever else may be the proper technical term to use, rest in full assurance of safety. To insure the necessary vigilance, these sentinels stand upon one foot, and hold in the other a large stone.[100] Should they inadvertently nod, the muscles relax and the stone drops, and by the slight noise it makes awakens them to a proper sense of their duty and their temporary lapse from it. A third valuable use that the cranes seem to have found for stones was to put them in their mouths when migrating, so that thus gagged they might not make a noise, and by their cries bring the eagles and other birds of prey upon themselves.[101] In the “Euphues,” we find a passage that admirably illustrates the belief in these two latter uses of the stone, as the author would naturally not use similes that would be unfamiliar to his readers. “What I haue done,” he writes, “was onely to keep myselfe from sleepe, as the Crane doth the stone in hir foote; and I would also, with the same Crane, that I had been silent, holding a stone in my mouth.” It will be sufficiently evident that the birds we have mentioned are but few in number. It would be extremely difficult to make our treatment exhaustive, extremely easy to make it exhausting; we would desire in pity to our readers to avoid either of these alternatives. We would therefore steer straight for the proverbial third course, and trust that it may be held that we have found a happy medium in resting satisfied with the comparatively few species of birds that are here brought under notice. CHAPTER V.