. The evolution and function of living purposive matter . acquirements. In the first part of this work (Human Speech) wereferred to the development and structural arrange-ment of the nervous substance of the spinal cord andbrain, so that it is unnecessary for us to recur to this ^ The term Neopallium ia employed to signify the pallium or cortex of that part of the cerebral hemispheres with which we aremainly concerned, as being distinct from the pallium of other lobesor regions of the brain. The term is well chosen by Professor G. ElliotSmith, because this cortex or pallium consists of superad
. The evolution and function of living purposive matter . acquirements. In the first part of this work (Human Speech) wereferred to the development and structural arrange-ment of the nervous substance of the spinal cord andbrain, so that it is unnecessary for us to recur to this ^ The term Neopallium ia employed to signify the pallium or cortex of that part of the cerebral hemispheres with which we aremainly concerned, as being distinct from the pallium of other lobesor regions of the brain. The term is well chosen by Professor G. ElliotSmith, because this cortex or pallium consists of superadded nervousstructures to those which exist in the lower classes of vertebrates(see p. 91). IN LOWER VEETEBEATBS 131 subject; but in order to explain the commandingpsychical powers possessed by human beings as com-pared with those of the lower animals, we must alludeto the increased complexity and to the great develop-ment of the neopallium or cortical areas of the cerebralhemispheres in man^ (Fig. 15). The cortical substance or neopallium of an educated. Srocas can^{ senso-motorspeech centre. CLuaictoruccntreOT area Fia. 15.—Diagram of loft cerebral hemisphere (outer surface) of human brain(From Halliburtons Handbook of Physiology, p. 688.) Englishmans brain averages, in its exposed and sunkensurface, about 200,000 square mm.; its thicknessvaries, but averages about 2 mm., and is formed offive strata or layers of cells, together with a mass ofnerve fibres with their supporting structure (neuroglia),blood vessels and lymphatics. With regard to the layers of cells which constitutethe outer gray substance of the cerebral cortex, they1 Human Speech, p. 154. 132 GANGLIONIC NEEVE CELLS may be described as forming five strata, from whichfibres proceed to other parts of the nervous system,and in which fibres terminate passing from all partsof the body. These five layers of cortical nerve-cellsand fibres may be represented in a diagrammatic form(Fig. 16). Superficial layer o
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