File:An American text-book of physiology (1897) (14783272845).jpg

Identifier: americantextbook00howe (find matches)
Title: An American text-book of physiology
Year: 1897 (1890s)
Authors: Howell, William H. (William Henry), 1860-1945 Bowditch, H. P. (Henry Pickering), 1840-1911
Subjects: Physiology
Publisher: Philadelphia : Saunders
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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e both physiological and histological,but it is to the latter changes only that attention will be here directed. Not only is the food-supply to the nerve-cells, as represented by the qualityand quantity of the plasma, variable, but the cells themselves are subject towide variations in their power to use the surrounding substances. When in a nerve-trunk containing both afferent and efferent spinal root-fibres passing to a limb, the afferent fibres are stimulated by a faradic currentapplied intermittently, changes in the cell-bodies in the spinal ganglion are tobe observed (Hodge). When this experiment is made on a cat, and, after death, the sectionsfrom the stimulated are compared with those from the corresponding but CENTRAL NERVOUS SYSTEM. 629 unstimulated spinal ganglion, a picture like that represented by Figure 157 isobtained.* The sections indiciitc that the cytoi)lasm together with the enclosed nucleusand nucleolus as well as the nuclei of the enclosing capsule of the cell, have
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Fig 157.-TWO sections, A and B, from the first thoracic spinal ganglion of a cat. B is from the gan-glion which had been electrically stimulated through its nerve for five hours. A, from the correspond-ing resting ganglion. The shrinkage of the structures connected with the stimulated cells is the mostmarked general change, n, nucleus; n. s, nucleus of the capsule; v, vacuole; X 500 diameters (Hodge). all suffered change by this treatment. The stimulus was applied for onlyfifteen seconds of each minute, the remaining forty-five seconds being given torest. In this way the cells here figured had been stimulated over a period offive hours. The nuclei of the sheath are flattened, the cytoplasm somewhatshrunken and vacuolated. With osmic acid the nuclei of the stimulated cellsstain more darkly and the cytoplasm less darkly than in a resting cell. Thenucleus is shrunken and crenated, and the nucleolus is also diminished in size.In the first experiments the attempt was made to demonstrate a

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