With regard to the nature of the material, in addition to the facts already mentioned, we may note that it is a substance easily moulded, especially when exposed to a gentle heat, such as is generated in a hive. It is light, so as to add little to the weight of the contents which will be stored in the cells. It is also a very slow conductor of heat, a matter of great importance both in summer and in winter. For, if it readily both absorbed and radiated heat, the temperature would, in the former season, become too high; while, in the winter, too great effort, and a large additional amount of food, would be needed by the bees to keep up the temperature of the hive to a point of safety for its inhabitants. Again, wax is a material which, by means of _propolis_ (of which we shall presently speak), admits of being fastened in position so securely as to be able to bear a great weight of brood, honey, and bee-bread, in the cells. The organs by which wax is secreted, and the implements with which it is fashioned, will be described fully in the chapter devoted to the physiology and anatomy of the bee; but we may say here that they are exceedingly simple, and that it is wonderful such beautiful work can be accomplished by means of them. But the manner in which comb-building is done is so marvellous, that it merits a detailed description. It is to Huber that we are indebted for the full exposition of this subject, and we cannot do better than quote his account of the process, as given by Kirby and Spence. We must premise, however, that the great naturalist thought there were two distinct classes of workers, the one of which he called the wax-makers; the other, the nurse-bees. Observations continued since his day have rendered it certain that this is a mistaken distinction. As a general rule the care of the young devolves, as we have already said, on the most recently hatched of the community, who are unfit, for some days after emerging from the cell, to take distant flight in search of stores from flowers. The older and stronger workers, on the other hand, go abroad for supplies, and then, on their return, secrete whatever wax is needed in the economy of the hive. [Illustration: Fig. 12.--Cluster of Bees.]