Yet the difference between such a building and a beehive is only one of degree. The same conditions are involved, and the same evils must be combated. Relatively, the problem is the same in each. In the case of the beehive, the necessity for this close system of life has been very gradually imposed on its inhabitants; and age-long custom, working on the individual, has at length produced a race marvellously adapted to its special needs. Probably the habit of retention of fæces while in the hive was at first a voluntary one. This, carried on from generation to generation, would react on the physical organism until use became second nature, and finally the present condition was reached. It is a fact that the bee is now incapable of voiding its excreta within the hive, or when at rest. The muscles involved can come into action only during, or immediately after, vigorous flight. In the winter, when long spells of cold occur, not a bee leaves the hive perhaps for weeks together; but an hour’s warm sunshine will infallibly bring the whole company out in a little eddying crowd about the hive, and then the necessary action of nature can readily be seen. These cleansing flights occur on all practicable occasions, and fulfil a double purpose; for when the cluster forms again, it will be between combs where the stores are unexploited, and the old, steady, upward feeding-march begins again in a new place. In extraordinary seasons, when the cold weather is much prolonged, the population of a hive may die of starvation within reach of plenty, no opportunity for these flights having presented itself, and the cluster therefore not having left its original station. And here the bee is plainly the victim of her own advanced acumen. Instinct would never have led her into such a foolish plight; but reason, being liable to err, errs here egregiously. The comparison of a modern beehive with a building similar in construction, and as densely crowded with human beings, brings the whole problem to a sharp definition. In such a building, unless a through-current of air could be established, the preservation of life must soon become impossible. Yet the bees have triumphantly overcome all difficulties. Whether in winter or summer, the air within the hive is almost as pure as that in the open, while the temperature can be regulated at will. For the ordinary purposes of the hive—honey-brewing, and the hatching of the young brood—it is kept uniformly at 80° to 85°. When the wax-makers are at work, it rises suddenly to 95° or so, while at the time of the swarming-fever it is often allowed to go even higher. In the hottest days of summer, however, unless the emigration-furore possesses the colony, the interior of a well-made hive seldom shows a temperature of more than 80°. And all this is brought about in a very simple fashion.