Having thus seen that in a way we have not hitherto recognized the same general principles pervade inorganic and organic evolution, let us revert to the case of super-organic evolution from which a parallel was drawn above. As analogous to the germinal mass of units out of which a new organism is to evolve, let us take an assemblage of colonists not yet socially organized but placed in a fertile region--men derived from a society (or rather a succession of societies) of long-established type, who have in their adapted natures the proclivity towards that type. In passing from its wholly unorganized state to an organized state, what will be the first step? Clearly this assemblage, though it may have within the constitutions of its units the potentialities of a specific structure, will not develop forthwith the details of that structure. The inherited natures of its units will first show themselves by separating into large groups devoted to strongly-distinguished occupations. The great mass, dispersing over promising lands, will make preparations for farming. Another considerable portion, prompted by the general needs, will begin to form a cluster of habitations and a trading centre. Yet a third group, recognizing the demand for wood, alike for agricultural and building purposes, will betake themselves to the adjacent forests. But in no case will the primary assemblage, before these separations, settle the arrangements and actions of each group: it will leave each group to settle them for itself. So, too, after these divisions have arisen. The agricultural division will not as a whole prescribe the doings of its members. Spontaneous segregation will occur: some going to a pastoral region and some to a tract which promises good crops. Nor within each of these bodies will the organization be dictated by the whole. The pastoral group will separate itself into clusters who tend sheep on the hills and clusters who feed cattle on the plains. Meanwhile those who have gravitated towards urban occupations will some of them make bricks or quarry stone, while others fall into classes who build walls, classes who prepare fittings, classes who supply furniture. Then along with completion of the houses will go occupation of them by men who bake bread, who make clothing, who sell liquors, and so on. Thus each great group will go on organizing itself irrespective of the rest; the sub-groups within each will do the same; and so will the sub-sub-groups. Quite independently of the people on the hills and the plains and in the town, those in the forest will divide spontaneously into parties who cut down trees, parties who trim and saw them, parties who carry away the timbers; while every party forms for itself an organization of "butty" or "boss," and those who work under him. Similarly with the ultimate divisions--the separate families: the arrangements and apportionments of duties in each are internally determined. Mark the fact which here chiefly concerns us. This formation of a heterogeneous aggregate with its variously adapted parts, which while influenced by the whole are mainly self-formed, goes on among units of essentially the same natures, inherited from units who belonged to similar societies. And now, carrying this conception with us, we may dimly perceive how, in a developing embryo, there may take place the formation, first of the great divisions--the primary layers--then of the outlines of systems, then of component organs, and so on continually with the minor structures contained in major structures; and how each of these progressively smaller divisions develops its own organization, irrespective of the changes going on throughout the rest of the embryo. So that though all parts are composed of physiological units of the same nature, yet everywhere, in virtue of local conditions and the influence of its neighbours, each unit joins in forming the particular structure appropriate to the place. Thus conceiving the matter, we may in a vague way understand the strange facts of autogenous development disclosed by the above named experiments.