. A manual of zoology. Zoology. S4 GEXERAI, TRIXCIPLES OF ZOOLOGY. telegraph system. These are to lie eonsiilered as the specihc element of the nervous system. Ill the vertebrates the ganglion ci;lls varv greatly in size; besides small elements there are large cells, only exceeded by the eggs in size, which correspondingly ha\e large nuclei recalling the germinal \esi- cles. Unipolar, bipolar, and multi- polar ganglion cells are recognized, the tlifterences depending upon the number of processes (nerve-tibres) which arise. In multipolar cells the number is large (fig. 52) and they are of two k
. A manual of zoology. Zoology. S4 GEXERAI, TRIXCIPLES OF ZOOLOGY. telegraph system. These are to lie eonsiilered as the specihc element of the nervous system. Ill the vertebrates the ganglion ci;lls varv greatly in size; besides small elements there are large cells, only exceeded by the eggs in size, which correspondingly ha\e large nuclei recalling the germinal \esi- cles. Unipolar, bipolar, and multi- polar ganglion cells are recognized, the tlifterences depending upon the number of processes (nerve-tibres) which arise. In multipolar cells the number is large (fig. 52) and they are of two kinds, dendrites and axons or )ictirilcs. DtiiJrilcs are so called because they branch again and again, not far from their origin from the cell. The axons (of which there is usually Init one to a gang- lion cell) can extend a long dis- tance without gi\'ing off" liranches, except here and there side twigs {colhilvrals) which arise at right angles to the main tlbre; tliev often continue into peripheral nerves. They branch at their tips (It'hnfciulro) so the mor- phological distinction from dendrites lies in the greater distance of the region of branching from the liody of the ganglion cell. In bijxilar ganglion cells Ijoth pirocesses appear as neurites, but if one is to be regarded as a dendrite with its branching at some distance from the cell, the definite physiological distinc- ,⢠1 . 1 ⢠1 1 ji t F' ^^.âMotor !»an!i;lion cell from the thoracic tion has to f)e m\-oked that ⢠,â ,, â i i <â 1 , t, n l region ot the spinal cord of a dog (atler Belhe). the neurite carries the im- ", nucleus. Fio 53.âMultipolar ganglion coll of man Vafter Gegenbaur). j, a.\ Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
