The population of a hive is very small during the winter in comparison with the vast numbers gathering produce in the summer--produce which they themselves live to enjoy but for a short period. So that not only, as of old, may lessons of industry be learned from bees, but they also teach self-denial to mankind, since they labour for the community rather than for themselves. Dr. Bevan, in describing the age of bees, thus adapts the well-known lines of Homer in allusion to the fleeting generations of men:-- "Like leaves on trees the race of bees is found, Now green in youth, now withering on the ground; Another race the spring or fall supplies, They droop successive, and successive rise." With regard to the functions of worker bees, Huber supposed that there were two distinct classes, one acting as gatherers of store and the other as nurses of brood. This however has been demonstrated to be a mistake, for the distinction is not one of class, but simply of age, the younger workers, for the first two or three weeks of their existence,[7] assuming the whole of the inner or home occupations--viz., those of feeding the larvæ, the queen, and the drones, and of making wax, building comb, and closing the cells, as well as keeping the hive in a state of cleanliness--and these duties they retain until themselves sufficiently vigorous to range the fields in quest of supplies. After this term of apprenticeship they enter upon the labours of adult bees, and collect honey, pollen, and propolis--particulars as to which functions, and that of wax secretion, will be found in the third and fourth sections of our next chapter, and in the sections devoted to these four items in Chapter VI. Water and salt are also brought in to aid in the sustenance of the young brood. The older bees perform the duties of the younger when there are none or insufficient of the latter in the hive; but they will hang about perfectly idle if kept at home by weather when there is a full staff of their younger sisters. These last, on the contrary, cannot possibly supply the places of the older until at the very least they have attained their eleventh or twelfth day. [Footnote 7: German observations cited by Von Berlepsch give from ten to nineteen days. The Baron gives provisionally the sixteenth day as the rule. The first sporting before the hive is given at from the fourth to the tenth day.]