ABSTRACT
The study of polymorphism has brought us to a realization of the significance of the social medium. In human society it is so complicated that probably few of us have a definite notion of what it is, though we all know that it is very important, but insect societies are so much simpler that they might be expected to yield a clearer conception of its nature. In one of my earlier lectures attention was called to the fact that the activities of social insects are merely modifications of the behaviour of their solitary ancestors. This is evident in the Aculeata and no doubt holds good also for the termites, although we know nothing of the habits of their solitary forbears, the Protoblattoidea. In the further discussion I shall therefore deal mainly with the Aculeata. The activities with which we are concerned are first, the nuptial or dissemination flight, second, nidification, third, foraging and storing food and its distribution among the members of the colony and fourth, defence. Among the solitary species these activities, with the exception of the nuptial flight or its equivalent, are carried on by the females exclusively. In the social species all four activities have become mass phenomena and are therefore intensified and modified, the nuptial flight but slightly, nidification and defence greatly, and most of all the trophic behaviour, which has to do with providing the adult and larval members of the colony with sustenance. The social medium, in very general terms, may be said to consist of these modified and intensified activities. Nidification and defence among the social Aculeates have had such a long and intricate evolution that their adequate presentation would require a special course of lectures. My time will permit me to consider only the trophic behaviour, to which all the other activities of the colony are really ancillary or contributory.
