Organic and functional nervous diseases; a text-book of neurology . e subject are to be found. LOCAL SYMPTOMS. 143 are joined. In order that sounds may be heard the temporal lobes areconnected. The anterior commissure of the brain joins the two tem-poral lobes ^gether. The commissural fibres between the greater partof the convexity of the hemispheres pass in the corpus callosum. The Association Areas of Flechsig.— The existence of areas of thecortex whose chief function is to receive and transmit association im-pulses has recently been proven by Flechsig, and his researches throwmuch light upo
Organic and functional nervous diseases; a text-book of neurology . e subject are to be found. LOCAL SYMPTOMS. 143 are joined. In order that sounds may be heard the temporal lobes areconnected. The anterior commissure of the brain joins the two tem-poral lobes ^gether. The commissural fibres between the greater partof the convexity of the hemispheres pass in the corpus callosum. The Association Areas of Flechsig.— The existence of areas of thecortex whose chief function is to receive and transmit association im-pulses has recently been proven by Flechsig, and his researches throwmuch light upon the function of those extensive areas of the cortexwhich have no known sensory or motor functions. It is known thatthe medullary sheath which surrounds and insulates the axone of eachneurone body develops after the axone. Flechsig has shown that theperiod at which this meduUation occurs differs in different functionaltracts during embryonal life. In the earliest stage but a few fibres aremeduUated. As the embryo grows, each system of neurones, one by Fig. Flechsigs diagram to show the order of development of the various areas of the surface. (Lancet, October 19, 1901.) one, completely develops, and by contrasting brains at different agesthese functional systems can be distinguished from each other. The chief sensory systems are the first to develop, the motor systemfollows, and at birth these tracts which bring the child into relationwith the outer world, projecting its impressions on his consciousnessand projecting his will, as shown by effort and act on the world, arecomplete. Later the various association-fibres within the brain areformed, so that as the sensory impressions are received they can berelated to one another, and a sensation can awaken its properlycoordinated motor response. Flechsig now distinguishes thirty-sixareas of the cortex of the brain, the neurones in each area becomingdeveloped at a different time from those in other areas. And h
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