. Diseases of the nervous system . n thepons, in the mid-brain andinter-brain). The whitesubstance itself containsnone of them. In manyareas of the gray substancethe nerve-cells are arrangedin groups. In the spinal cord, es-pecially in the dorsal por-tion, segmentation may be recognized from above downward, a metamericarrangement. In a horizontalsection there is seen a three-fold grouping of the anteriorhorn cells, especially in thecervical, cord, to which is addedthe cell group of Clarkes col-umn in the thoracic are also numerous nerve-cells which are apparentlydistributed irregula
. Diseases of the nervous system . n thepons, in the mid-brain andinter-brain). The whitesubstance itself containsnone of them. In manyareas of the gray substancethe nerve-cells are arrangedin groups. In the spinal cord, es-pecially in the dorsal por-tion, segmentation may be recognized from above downward, a metamericarrangement. In a horizontalsection there is seen a three-fold grouping of the anteriorhorn cells, especially in thecervical, cord, to which is addedthe cell group of Clarkes col-umn in the thoracic are also numerous nerve-cells which are apparentlydistributed irregularly through-out the gray substance of thespinal cord. The entire cortex of thebrain shows the nerve-cellsarranged in layers, which dif-fer from each other in shapeand size. The nerve-cells ac-cumulate near the origin ofthe nerves of the brain, also FlG 35in its central ganglia and inthe gray nuclei of its trunk. The majority of these send nerve processesfrom the gray substance into the white; a few nerve-cells, usually the smaller. -Glia Cells (Spindle Cells). (After Kolliker.) THE GROUPING OF THE NERVOUS SUBSTANCES 45 whose nerve processes are very limited in extent, remain wholly the nerve-cells are partially onesthe gra\ grouped and partly isolated, so also the nerve fibers of the white substance either unite with well known nerve tractsand form columns, or pursue their own paths which are still unknown. The columnar nerve tracts within the central nervous system pass fromone structure to another by longer or shorter paths. At certain points uponthe same side of the brain and spinal cord they unite with one another {asso-ciation system), or at corresponding points on different sides {coordinationsystem), or they pass caudalward from the cortex of the brain to the centralganglia, or even lower down into the spinal cord {projection systems). Someof the latter unite directly or indirectly with those coining from the brainand spinal cord and with the nerves ex
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectnervoussystem, bookye
