The reactions in which the social instinct manifests itself are not all equally developed in the different social species. It is true that there is a certain group of characteristics common to all social animals; but it is also found that in one example there is a special development of one aspect of the instinct, while another example will show a characteristic development of a different aspect. Taking a broad survey of all gregarious types, we are able to distinguish three fairly distinct trends of evolution. We have the aggressive gregariousness of the wolf and dog, the protective gregariousness of the sheep and the ox, and, differing from both these, we have the more complex social structure of the bee and the ant, which we may call socialized gregariousness. The last-named is characterized by the complete absorption of the individual in the major unit, and the fact that the function of the social habit seems no longer to be the simple one of mere attack or defence, but rather the establishment of a State which shall be, as a matter of course, strong in defence and attack, but a great deal more than this as well. The hive is no mere herd or pack, but an elaborate mechanism for making use by co-ordinate and unified action of the utmost powers of the individual members. It is something which appears to be a complete substitute for individual existence, and as we have already said, seems like a new creature rather than a congeries united for some comparatively few and simple purposes. The hive and the ant’s nest stand to the flock and the {167} pack as the fully organized multicellular animal stands to the primitive zooglœa which is its forerunner. The wolf is united for attack, the sheep is united for defence, but the bee is united for all the activities and feelings of its life. Socialized gregariousness is the goal of man’s development. A transcendental union with his fellows is the destiny of the human individual, and it is the attainment of this towards which the constantly growing altruism of man is directed. Poets and prophets have, at times, dimly seen this inevitable trend of Nature, biology detects unmistakable evidence of it, and explains the slowness of advance, which has been the despair of those others, by the variety and power of man’s mind, and consoles us for the delay these qualities still cause by the knowledge that they are guarantees of the exactitude and completeness that the ultimate union will attain.