. Animal biology; Human biology. Parts II & III of First course in biology. Biology. -/node. Mtfe- FIG. 103. — Showing a NEU- RON, A, or nerve cell with all its parts — dendrites, cell body, and axon ; B, a portion of a white fiber highly magnified. (Jegi.) municate with every other sub- scriber, would need one thousand wires running into his house; all together, there would have to be several hundred thousand (to be exact, 499,500) wires. With a cen- tral office only one thousand are needed. As a telephone system has central offices, so the nervous system has nerve centers. Nerve centers
. Animal biology; Human biology. Parts II & III of First course in biology. Biology. -/node. Mtfe- FIG. 103. — Showing a NEU- RON, A, or nerve cell with all its parts — dendrites, cell body, and axon ; B, a portion of a white fiber highly magnified. (Jegi.) municate with every other sub- scriber, would need one thousand wires running into his house; all together, there would have to be several hundred thousand (to be exact, 499,500) wires. With a cen- tral office only one thousand are needed. As a telephone system has central offices, so the nervous system has nerve centers. Nerve centers contain nerve cells. Al- though there are some subordinate nerve centers in the spinal cord, the greatest collection of nerve centers in our bodies is in the skull, and is called the brain. Fishes were the lowest animals studied in animal biology found to possess a true brain. The nervous system, unlike a telephone system, has other duties besides allowing communication. It enables us to think, and, after reflection, to will and to act by con- trolling the various organs. The Units of which the Nervous System is Constructed. - - A nerve cell with all its branches, or fibers, is called a neuron (see Fig. 103); some neuron branches are several feet long. Neurons are the units that compose the nervous system. The living substance in cells is. 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 Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan Co.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1910
