Introduction to physiological psychology / by Theodor Ziehen ; translated by C.C. van Liew and Otto W. Beyer.

  • Theodor Ziehen
Date:
1909
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Licence: In copyright

Credit: Introduction to physiological psychology / by Theodor Ziehen ; translated by C.C. van Liew and Otto W. Beyer. Source: Wellcome Collection.

    91/334 (page 69)
    indebted for some excellent investigations in this field, assumes another diffused general sense of feeling as operating between the different points of pressure. His hypothesis does not seem to be well grounded. Electrical stimulation, especially that of faradic electricity, acts upon all points of sensation, whether of temperature or pressure; but it imparts only sensations of cold at the “ cold-spots,” only sensations of heat at the “ heat-spots,” and only sensations of touch at other points. According to Goldscheider, a strong mechanical stimulus applied to the spots for temperature imparts a corresponding feeling of temperature. It must also be mentioned that there is still considerable doubt as to what the real, active element is in the case of caloric stimuli. E. H. Weber thinks that irritation is produced by the rise and fall of the temperature of the skin ; Vierordt thinks it is produced by the direction of the current of heat passing through the skin; Hering ascribes it to the absolute deviation of the temperature of the cutaneous nerve-apparatus itself from a physio logical zero-point of temperature at which neither warm nor cold is perceived. It has not yet been determined as to where the central terminations of the sensory fibres of feeling are to be found. At one time the Gyrus fornicatus was designated as the cortical centre for sensations of feeling; then it was thought that this cortical centre coincides with the so-called motor region in which the path for the conduction of voluntary motor impulses originates. But the skin is not the only organ containing sensory nerve- ends. We find them also scattered through all the organs of the human body. These so-called “organic sensations” are dis- tinguished by great indefiniteness and slight intensity under normal conditions. Only one more group of the more deeply seated sensory nerves deserves mention as being of special im- portance; it is that group of nerves whose terminations have been shown to penetrate the synovial duplicatures of the joints, the ligaments, tendons, and muscles. By means of the sensory nerves of the ligaments and muscles, for example, we perceive the condition of the muscles, their contraction and tension