II. TYPE SUB-DOLICHOCEPHALIC-INDEX ABOVE 75 AND UP TO 77.77.

IV. SUB-BRAchycephalic TYPE-INDEX ABOVE 80 AND UP TO 83.33.

The comparison between the human species and the anthro-

poid apes, in this respect, shows that the differences are so great,

that we can conclude after considering all which precedes, and neglecting other relations, that man constitutes a species distinct from the anthropoid apes, laying aside all questions of origin and descent. Man is superior to the anthropoid apes in the proportion of the parts of the body, in the size of the cranial cavity, in weight, in the convolutions of the brain, in quantity of gray matter, and in structure, mass, and quality of thinking material. This superiority is manifested in a palpable manner by definite characteristics excluding all real confusion between the anthropoid apes and man. Man forms a distinct species by reason of appropriate variations and by digression of these from the maximum limits, from the variations of inferior beings. In return the sense cavities are more developed among animals, the orbits, nasal cavities, sinus, masticating apparatus. Although inferior from the muscular point of view, to many animals, man is capable of more complex movements; from the point of view of sensibility and intelligence, he surpasses all. If, anatomically, the anthropoid apes are still nearer man than they are to the ordinary monkeys, for example, from the point of view of the cranial capacity and weight of the brain, there is nevertheless between them and the inferior varieties of humanity a considerable difference of which the intermediary stages have disappeared and nothing has come forth to supply them. Moreover, this difference from the anthropoid apes makes man's progress more rapid. There results a differentiation co-ordinating the skeleton, muscles, viscera, and eyes. This gives man the power of scientific observation, of prevision, and foresight.

The difference between the two species tends to become greater in proportion as the inferior populations disappear, whether by extinction or by fusion with civilization, and, on the other side, as the anthropoids themselves become eliminated.

On the whole, there is a general type, clearly determined and limited, common to all the mammalia; a particular type common to all the primates, comprising the monkey, anthropoid ape, and man; a more special type common to the anthropoid apes and to man; and, finally, a human type anatomically and physiologically determinate and recognizable. This human

structural type is capable of more complex and numerous equilibrations 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 individualsocial 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 nineteenth 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 structure of which the elements are discontinuous can, however, exercise 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 foundation. This conception is destined to give us a better comprehension 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 fœtus, 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

membrane, which shows a considerably different development in man, where the zones of association are the centers of intellectual functions.

The essential point of the theory of Flechsig is that, contrary to what' was accepted, all the zones of the cerebral cortex are not connected by bundles of fibers to the lower part of the gray matter. The cerebral cortex is divided into (a) zones or centers of projection, or sensorial spheres, and (b) zones of the membrane, comprising all the parts of the latter with exception of those connected with the fibers of projection, but connected by numerous fibers of association to the sensorial spheres and to one another. The centers of projection are both sensitive and motor. Their extent or limits are determined by the number of fibers they receive and send out in proportion to their surface. There are three zones of association: (1) the large posterior center of association, comprising a part of the lingual convolution, the fusiform convolution, the two parietal convolutions, the lower temporal and anterior part of the occipital lobe; (2) the middle center of association, comprising the insula de Reil; (3) the anterior center of association, formed by the anterior part of all the frontal convolutions and then by the convolutions on the orbital surface.

In comparing the results of the researches of Flechsig, it is shown that the zones of association in man correspond to twothirds of the cortical surface, and the zones of projection to only one-third. As one descends the animal scale, one sees that in the monkey the proportion is the same for each of the parts; then in the mammalia the zones of association diminish more and more until the zones of projection exist almost alone.

The essential character of the zones of association is in not having a direct connection with the lower gray masses that is, in being independent. No impression from the periphery reaches them without the mediation of the centers of projection, and no imitation can emanate from the zones of association without passing by those of projection.

The centers of association receive impressions by the sensorial spheres, focus and compare them, and form the substratum

of our experience, of our science and philosophy. They hold the zones of projection under their control, exercising on them an inhibitory or stimulating action from the point of view of our acts. To them alone belong conscious and especially

methodical action.

The large posterior center of association plays perhaps the most important rôle. It is highly developed among intelligent men, but small among defectives. It may be noted that it is inserted between three of the most important sources of impressions: the tactile, auditory, and visual zones. On the contrary, the middle center, insula de Reil, is only between the tactile and olfactory sphere. The most scientific and precise impressions are then in relation with the former.

Thus in the constitution and evolution of the human nerve substance we have the substratum of intellectual development. In the prosencephalon the sensitive centripetal fibers are the first to develop the myelines and function. They appear at about the eighth month of the intra-uterine life. When these sensitive fibers have appeared, then the sensations stimulate the centers, and the myeline appears in the fibers of centrifugal projection toward the end of the first month of the extra-uterine life. At this period only the centers of projection have developed the myeline and become active; the acts of the child are still cortical reflexes; the memory of impressions is not yet fixed in the brain. The latter from this point of view resembles animals without centers of association. All the impressions are received singly and are not compared. In the second month the myeline fibers appear and start from the sensorial spheres, going to the zones of association, and at first to the neighboring parts of the zones of projection. Then the memory of impres sions is stored up. The child begins to recognize what it feels, sees, etc. Then the fibers of association, penetrating still farther, connect certain different spheres; for example, the auditory sphere with the lower part of the tactile sphere; the child is able to repeat the words heard, without comprehending their meaning. Finally, all the spheres of association being connected, the images can be compared. The child will reason, comprehend,