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structural type is capable of more complex and numerous equi- librations and adaptations than any other mass of inorganic or organic matter of nature. Its motility and thought extend beyond the limits of the earth. This is especially true when we view it not simply as individual, but also in its proper milieu, the social, where it takes on its integral aspect of individual- social existence. Then the muscles and brain co-operate in collective efforts of incomparable extent, duration, intensity, and equilibrium.
6. Centers of association. Psychology, at the end of the nine- teenth century, has been changed by the application of the experimental method and by a more exact knowledge of the nature of the nervous system. The school of Wundt for method, the works of Ramon y Cajal and Flechsig for the nervous system, have completed the basis of sociology in facilitating, by analogy, the conception of social statics and dynamics. The discoveries of Ramon y Cajal have shown that a nervous struc- ture of which the elements are discontinuous can, however, exer- cise a continuous action ; those of Flechsig, that the association of ideas, generalization, and abstraction have their parallels in the nervous system, and that consequently the philosophical power of the human species, that by which it is distinguished from all other forms, also has its material and physical founda- tion. This conception is destined to give us a better compre- hension of the fact that all social phenomena are at the same time inorganic, organic, and psychic, and that our faculties of perception, generalization, and abstraction find their basis in the substance and organization of the nervous system through which all ideology is connected to inorganic nature through the mediation of organized substance.
After a quarter of a century of patient research, Flechsig, professor of psychiatry at Leipzig, has established the order of appearance of myeline in the nerve fibers by a comparison of the brain of embryos, of the foetus, and of infants. It results from this that if, at the beginning of the average brain, the resemblance between the nervous system of man and that of the mammalia is considerable, there is no resemblance in the cerebral
