. Kirkes' handbook of physiology . ior-horn cells. Functions of the Cerebellum. With the exception of its middlelobe, the cerebellum is itself insensible to irritation and may be all cut awaywithout eliciting signs of pain (Longet). Its removal or disorganization bydisease is also generally unaccompanied by loss or disorder of sensibility;animals from which it is removed can smell, see, hear, and feel pain, to allappearances, as perfectly as before (Flourens; Magendie). It cannot, there-fore, be regarded as a principal organ of sensation. Yet if any of its crura FUNCTIONS OF THE CEREBELLUM 565
. Kirkes' handbook of physiology . ior-horn cells. Functions of the Cerebellum. With the exception of its middlelobe, the cerebellum is itself insensible to irritation and may be all cut awaywithout eliciting signs of pain (Longet). Its removal or disorganization bydisease is also generally unaccompanied by loss or disorder of sensibility;animals from which it is removed can smell, see, hear, and feel pain, to allappearances, as perfectly as before (Flourens; Magendie). It cannot, there-fore, be regarded as a principal organ of sensation. Yet if any of its crura FUNCTIONS OF THE CEREBELLUM 565 be touched, pain is indicated; and, if the restiform tracts of the medulla ob-longata be stimulated, the most acute suffering appears to be produced. These phenomena may properly be ascribed to the activity of the cerebralcortex, since the number of collaterals on the fibers that pass to cerebellar tractsis very great, and impulses arising from their stimulation may reach the sen-sorium by paths other than through the Cranial Nerve(Vestibular) Fig. 396.—Scheme of Principal Ascending Cerebro-Spinal (black) and Cerebellar (red) Con-duction Paths. (Modified from Hardesty in Morris Anatomy.) The experiments of Longet and many others agree in supporting the viewthat no stimulation of the cerebellar cortex leads to localized muscular con-tractions. In other words, there is no localization in the cerebellar cortexas in the cerebrum, the cerebellum apparently acting as a whole. If the cere-bellum be removed, as was done by Flourens and numerous later physiologists,a very profound disturbance in motor functions occurs. With the removal 566 THE nervous system of the superficial layers of the cerebellum, in pigeons particularly, there isincreasing feebleness and lack of harmony of the muscles concerned in lo-comotion. When the entire organ is cut away in pigeons they lose the power ofwalking, flying, and of standing in the usual erect way. Their power of pre-serving equili
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