Identifier: textbookofphysio1916howe (find matches)
Title: A text-book of physiology : for medical students and physicians
Year: 1916 (1910s)
Authors: Howell, William H. (William Henry), 1860-1945
Subjects: Physiology Medicine
Publisher: Philadelphia and London : W. B. Saunders Company
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library

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conductingstructure along which passes the nerve impulse. The arrangementof these fibrils within the cell is not completely known, the resultsobtained varying with the methods employed. A matter of far-reaching importance on the physiological side is the question of PROPERTIES OF THE NERVE CELL. 135 the existence of an extracellular nervous network. Most recenthistologists agree in the belief that there is a delicate networksurrounding the cells and their protoplasmic processes. Thispericellular net or Golgis net is claimed by some to be a ner-vous structure connecting with the neurofibrils inside the celland forming not only a bond of union between the neurons, butpossibly also an important intercellular nervous structure thatmay play an important role in the functions of the nerve centers.This view is represented schematically in Fig. 64. According toothers, this network around and outside the cells is a supportingtissue simply that takes no part in the activity of the nerve units.
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Fig. 64.—Bethes schema to indicate the connections of the pericellular network:Rz, A sensory cell in the posterior root ganglion; the fibrils in the branch that runs to thecord are indicated as connecting directly with the pericellular network of the motor cells,Gz. General Physiology of the Nerve Cell.—Modern physiologistshave considered the cell body of the neuron, including the den-drites, as the source of the energy displayed by the nervous system,and it has been assumed that this energy arises from chemicalchanges in the nerve cell, as the energy liberated by the musclearises from or is dependent upon the chemical changes in its sub-stance. It would follow from this standpoint that evidences ofchemical activity should be obtained from the cells and that theseelements should exhibit the phenomenon of fatigue. Regardingthis latter point, it is believed in physiology that the nerve cells doshow fatigue. The nerve centers fatigue as the result of continuousactivity, as is evident

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