Certain observers have thought they noticed differences in the size of the full-grown workers, and supposed that these variations were connected with diversity of occupations and duties. But as all have their several organs and their whole structure precisely alike, and as little direct evidence of special functions has been adduced, it is tolerably certain that any peculiarities in regard to size must be otherwise explained. Nor is it difficult to discover how these may have been brought about. For, since each pupa leaves behind it some portion of the silken cocoon it had spun, it is clear that after a succession of young bees from the same cells, these must become sensibly contracted in extent, so that the later progeny will not have had as much space in which to grow as their elder-born sisters had, and hence are, at least when they emerge, smaller in size. Huber, without reference to the above-mentioned fact, supposed that separate duties were undertaken by special bees, at least so far as the gathering of stores and the care of the young were concerned. Subsequent observations, however, tend to show that the latter office is undertaken by the most recently born young, till they themselves have become strong enough to fly abroad in search of honey and pollen. It is said they also see to the making of wax, the building of comb, and the cleansing of the hive, during the first two or three weeks of their life. Some corroboration of this idea is given by the circumstance that, if there be not sufficient room for the extension of a very strong population in their abode, and the conditions for swarming are not satisfactory, the older bees will remain idle in clusters, often outside the hive, leaving to the younger ones the execution of the internal work. Sir John Lubbock has recorded a series of observations which seem to indicate that certain individuals are stationed near the entrances as sentinels. In his most interesting work on _Ants, Bees, and Wasps_, he says:-- "On October 5th I called out the bees by placing some eau-de-Cologne in the entrance, and marked the first three bees that came out. At 5 P.M. I called them out again. About twenty came, including the three marked ones. I marked three more. "October 6. Called them out again. Out of the first twelve, five were marked ones. I marked three more. "October 7. Called them out at 7.30 A.M. as before. Out of the first nine seven were marked ones. At 5.30 P.M. called them out again. Out of six, five were marked ones. "Octobers. Called them out at 7.15. Six came out, all marked ones. "October 9. Called them out at 6.40. Out of the first ten, eight were marked ones. Called them out at 11.30 A.M. Out of six, three were marked. I marked other three. Called them out at 1.30 P.M. Out of ten, six were marked. Called them out at 4.30. Out often, seven were marked.