associated with a large amount of independence. The case is that of certain rather small "short-tongued " bees (species of Halictus), which are represented in the British fauna. There are here no workers, but by the united labours of a number of females a branching underground passage is dug out at night, there being a single opening to the exterior, and close to this an enlargement or “hall" for the greater convenience of individuals wishing to pass one another. Within this underground home each female makes her own particular nest, consisting of ovoid waterproof cells, and attends to her domestic duties after the fashion of solitary species. A sentinel is said to be posted at the common opening of the burrow, so that some understanding would seem to be arrived at in the matter of mounting and relieving guard. But, apart from this, the individuals living together have no more social organization than the different families occupying a dwelling made up of a set of "flats", who use a common stair and the same street door. If the said families had constructed these by their joint efforts the analogy would be more complete.

The last example is a sort of side-branch in social evolution; for a comparatively simple case in the direct series of adaptations we may turn to the large insects familiarly known as Humble-Bees (species of Bombus), which are well represented in our own country, and live above or under the ground in communities which endure for a single year only. They exemplify the beginning of the caste-system, for in addition to males there are three varieties of the opposite sex, i.e. queens, small females, and workers, which in appearance and structure resemble one another pretty closely. We do not find the same marked differences that exist between the queen and worker in honey-bees, while the power of egg-laying is not restricted to the queen, though she is the mother of most of the members of the community. The habits of several species have been closely observed, and the succession of events is somewhat as follows. A queen which has survived the winter begins her work as foundress of a society when the spring is well advanced, and food in the form of nectar and pollen is abundant. Selecting a sheltered spot, on the surface or below the ground according to the species, she successively constructs two or three large waxen cells, the material for which is derived (as in social bees generally) from a number of small glands that open on the under side of her abdomen: a

proportion of pollen being added. being added. When a cell is of full size it is lined with a mixture of pollen and honey, several eggs are laid in it, and a roof is put on. After several days' rest the next cell is made, and stocked in the same way. About the time that the second cell is completed duties of another kind are added to the tale of work. For, meanwhile, the eggs first laid have hatched out, and the bee-grubs, having exhausted their scanty store of provisions, require feeding. To do this their mother bites a hole in the enclosing cell, and supplies honey from her mouth as required. Here, and in other cases, the "honey" is not the same thing as the "nectar" found in flowers. A bee swallows the latter, taking it into a crop or "honey-bag", into which the gullet dilates. Within this receptacle it undergoes a kind of fermentation by which it is converted into honey. So far the life-history is much like that of a solitary form, all the work being done by the mother. But in the next stage division of labour begins to play an important part. The full-fed grubs spin silken cocoons, and pass into the quiescent or pupa stage, from which they emerge as "workers". By gnawing away the wax the queen assists their escape from the enclosing cell. As workers become numerous they justify their name by undertaking the labours of building and storing, ultimately enabling the queen to devote herself entirely to egg-laying. For each egg a separate cell is constructed. As the community increases in size small females may be produced, and towards autumn larger "drone cells" are made, and still larger "queen cells". It is stated that these are not stored with food, the corresponding grubs being from the first assiduously nursed by the workers. By the time that drones and queens are mature the community has attained its full size, and may consist of from 300 to 400 individuals, under favourable circumstances. The pairing of the young queens in the course of a nuptial flight constitutes the climax of the year's drama, for as winter approaches the temporary community becomes disintegrated. All the workers and drones perish, together with many of the queens, but some of the latter live through the winter in a torpid state to found fresh societies the following spring. It should be added to this account that when the community is in full working order special unclosed cells are made, to be stored with honey or pollen for general use. These "honey tubs" and "pollen tubs" serve as a larder, which

is constantly being replenished during fine weather, to be drawn upon when it is wet. Old brood-cells may be enlarged for the same purpose, but are never put to their original use a second time.

The

For one species of Humble-Bee (Bombus ruderatus) a remarkable arrangement has been described. It is said that in every nest one bee is told off as a "trumpeter". This individual sounds reveillé at from 3 to 4 a.m., rousing her fellows to the labours of the day, and if removed is replaced by another. habit of storing food, existing to some extent in Humble-Bees, is carried much further in the Honey-Bee (Apis mellifica) and its numerous relatives, and has probably had much to do with the evolution of the complex social life which these exhibit. It enables a community to live on through the unfavourable season of the year, thus becoming permanent, and this continuity has rendered possible division of labour to a greater degree, being at the same time associated with well-marked differences between the castes, so far as queen and workers are concerned. The former is of comparatively large size, and her only duty is to produce eggs, while the varied labours of the hive fall to the lot of her smaller sisters. The community is only temporary as regards the drones, none of which survive the winter, but are replaced by a fresh set which hatch out the following year. A few further details regarding the Honey-Bee will be given in a later section.

The Social WASPS (Vespida) live in communities which, so far as at present known, exist for one season only, as in HumbleBees, to which they present a further resemblance in the fact that the workers are not markedly unlike the queen, and are more or less capable of laying eggs. The building-material, however, is not wax but a sort of paper, made by chewing woody matter and mixing it with a fluid secreted by certain glands of the mouth-region. We may take to illustrate the annual cycle one of three British species (Vespa Germanica, fig. 1096) in which the nest is constructed underground. The foundress queen begins work in spring, making a small number of cells in the place which is to be the top of the nest, and depositing an egg in each. The cells are neither stored nor closed. Her next task consists in feeding the grubs as they hatch out, first with honey or fruitjuice, and later with the bodies of insects, especially flies. By

means of her strong jaws she removes the hard parts of the prey, chewing up the rest into a kind of mince-meat adapted to the tender digestions of her offspring. When they have reached their full size the grubs spin cocoons and pass into the pupa stage, from which they emerge as worker wasps about four weeks after the date when the eggs were laid. Without loss of time these take over the work of building and nursing, and even feed their mother, who soon has nothing to do but lay eggs in the cells as they are constructed. The complete

nest consists of a series of combs, connected by little pillars, and the building operations are carried on from above downwards. Each comb is made up of a large number of roughly hexagonal cells, the mouths of which are directed downwards. Towards the end of summer cells of larger size are made, in which queens and and drones are reared, but many of the latter are brought up in the ordinary small cells. After mating has taken place the community is soon broken up; most of the insects die, but some of the queens survive the winter, and found the communities of the following year. Wasps appear to be extremely sensitive to cold, and it is perhaps partly for this reason that the nest is surrounded with a covering made up of layers of paper (see fig. 1096).

e.g., Entrance gallery; s.g., side galleries; 1-7, combs connected

by pillars (7 above main figure shows arrangement of the three

cells of the youngest comb); env., papery envelope of nest; r., root

to which first foundation is attached (other roots with secondary

attachments also shown); a.n., part of an ant's nest; A.., larvæ of a fly; m.b., mole burrow.

The nests of many species of social Wasp are suspended from plants, while the Hornet (Vespa crabro) prefers to build in a hollow tree. There is a large amount of variation as to size, shape, and durability, while in some cases earth is added to the ordinary building material.

The social habits of ANTS are even more complex than those of Bees and Wasps, and some account has already been given of the way in which the members of certain species procure and store food (see vol. ii, pp. 103 and 206). There is no more fascinating department in the whole realm of natural history than the study of ant life, for these little creatures live in a wonderland which is all their own. The elaboration of some of their communities is very considerable, and the welfare of the individual is rigorously subordinated to the interests of the species. Some of the more salient points are thus ably summarized by Sharp (in The Cambridge Natural History):-"Observation has revealed most remarkable phenomena in the lives of these insects. Indeed, we can scarcely avoid the conclusion that they have acquired in many respects the art of living together in societies more perfectly than our own species has, and that they have anticipated us in the acquisition of some of the industries and arts that greatly facilitate social life. The lives of individual ants extend over a considerable number of years-in the case of certain species at any rate,—so that the competence of the individual may be developed to a considerable extent by exercise; and one generation may communicate to a younger one by example the arts of living by which it has itself profited. The prolonged life of ants, their existence in the perfect state at all seasons, and the highly social life they lead are facts of the greatest biological importance, and are those that we should expect to be accompanied by greater and wider competence than is usually exhibited by Insects. There can indeed be little doubt that ants are really not only the 'highest' structurally or mechanically of all insects, but also the most efficient. There is an American saying that the ant is ruler of Brazil. We must add a word of qualification; the competence of the ant is not like that of man. It is devoted to the welfare of the species rather than to that of the individual, which is, as it were, sacrificed or specialized for the benefit of the community. The distinctions between the sexes in their powers or capacities are astonishing, and those between the various forms of one sex are also great. The difference between different species is extreme; we have, in fact, the most imperfect forms of social evolution coexisting, even locally, with the most evolute. These facts render it extremely difficult for us to appreciate the ant; the limitations of efficiency displayed by the individual being in some

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