I. S o c ie t ie s of invertebrate animals frequently exhibit structures, or patterns, upon which the life of the individual is essentially dependent. But on this level the social structure is individualistic in its transmission; it is deter mined by the specific organismic structure of the com ponent individuals. Among higher vertebrates which are characterized by a greater plasticity of individual be haviour, social ways are gradually built up, accumulated, interrelated, and transmitted in social tradition inde pendently of changes in physiological inheritance. Thus birds or apes, to a slight degree, and human beings, to a very high degree, are “ social animals ” in a sense which is not true of ants or parasites. Personality and behaviour are largely constituted on this level by social processes.