File:Kirkes' handbook of physiology (1907) (14583265549).jpg

Identifier: kirkeshandbookof00kirk (find matches)
Title: Kirkes' handbook of physiology
Year: 1907 (1900s)
Authors: Kirkes, William Senhouse, 1823-1864 Greene, Charles Wilson, 1866-1947
Subjects: Physiology
Publisher: New York, W. Wood and company
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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discussed under two headings: The function of thecell body, and the function of the cell processes. The cell body of the nerve cell is the part that contains the nucleus and isthe center of those activities which influence the metabolism of the cell itself.If the cell body be isolated from its processes, the processes will degenerate,while the body continues to live. In other words, the cell body may be con-sidered as the center of those trophic influences which regulate the nutritionof the processes. Although the nerve cell as a whole is in many, perhaps in THE CHARACTERISTICS OF THE INDIVIDUAL NERVE CELL 505 most, cases a conducting organ, still those physiological processes which go onin it produce marked changes in the protoplasm of the cell body. Hodge hasdemonstrated that nerve cells which have been active for several hours, incase of sparrows which have been flying about actively throughout the day, or inbees after a days work, show marked evidences of fatigue. These evidences
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Fig. 356 A.—Spinal Ganglion Cells from the Cat. A, Normal taken before stimulation; B, takenalter five hours stimulation. From the right and left, eight thoracic ganglia. (Hodge..) consist in the decrease in the size of the nucleus and the appearance ofvacuoles in its structure, also in the shrinking of the protoplasm of the cell,which, in case of the cells of the spinal ganglia, iraws away from its capsule.If the cells are examined early in the morning, then these fatigue changes willnot be present, the cell having recuperated during the rest of the night. It 506 THE NERVOUS SYSTEM has also been found that the Nissl granules which are present in the cell bodyof resting cells decrease in number and show evidence of disintegration incells that have been stimulated for several hours. The nerve processes or fibers are primarily conducting structures. Buttheir fibers are susceptible to artificial stimulation, as shown in the previouschapter, that is, they are irritable. They are influen

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