The mesmeric mania of 1851, with a physiological explanation of the phenomena produced : a lecture / by John Hughes Bennett, M.D.

  • Bennett, John Hughes, 1812-1875.
Date:
1851
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Licence: Public Domain Mark

Credit: The mesmeric mania of 1851, with a physiological explanation of the phenomena produced : a lecture / by John Hughes Bennett, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    Sensation may be defined to be the consciousness of an impression, and tliat it may take place, it is necessary,—Ist, That a stimulus should be applied to a sensitive nerve, which produces an impression ; 2d, That, as the result of this impression, a sometliing should be generated, which we call an influence, which influence is conducted along the nerve to the hemispherical ganglion ; 3d, On arriving there, it calls into action that faculty of the mind called consciousness or perception, and sensation is the result. It follows that sensation may be lost by any circumstance which destroys the sensibility of the nerve to impressions, which impedes the process of conducting the influence generated by these im- pressions, or, lastly, which renders the mind unconscious of them. Illustra- tions of how sensation may be afl^ected in aU these ways must be familiar to you from circumstances influencing the ultimate extremity of a nerve, as on exposing the foot to cold,-from injury to the spinal cord, by which the com- munication with the brain is cut off, or from the mind being inattentive, excited, or suspended. . Of the nature of nervous influence we know nothing. Its traversing the nervous cords with inconceivable rapidity, presents a certain analogy to elec- tricity passing along a wire. But that nervous influence is not electricity is proved by the fact, that the former can never be transmitted by anything but nerve, whereas the latter may be sent along a variety of conductors, of which nerve is one of the worst. Again, whenever an animal really evolves electricity, like the electric eel, it is furnished with a distinct organ for the ^Vhe independent endowment of nerves is remarkably well iUustrated by the fact that whatever be the stimulus which caUs their sensibility into action, the same result is occasioned. Mechanical, chemical, galvamc, or other physical stimuli, when applied to the course or the extremities of a nerve, cause the very same results as may originate from suggestive ideas, perverted ima- gination, or other psycldcal stimuli. Thus a chemical in-itant, galvamsm, or pricking and pinching a nerve of motion, will cause convulsion and spasms of the muscles to which it is distributed. The same stimuli applied to a nerve of common sensation will cause pain, to the optic nerve flashes of Ught, to the auditory nerve ringing sounds, and to the tip of the tongue peculiar tastes. Again, it will be seen that suggestive ideas, or stimuli arising in the mind, may induce peculiar effects on the muscles ; give rise to pain or insensibihty, and cause perversion of all the special senses. Motion is accomplished through the agency of muscles, which are endowed with a peculiar vital property, called contractility, in the same way that nerve is endowed with the property of sensibility. Contractility may be called mto action altogether independent of the nerves (Haller), as by stimulating an iso- lated muscular fasciculus directly (Weber). It may also be excited by physical or psychical stimuli, operating through the nerves. Physical stimuli applied to the extremities or the course of a nerve, may cause convulsions of the parts to whicli the motor filaments are distributed directly, or they «^*y bined movements in other parts of the body dia^taUically (Marshall Hali;,- that is, through the spinal cord. In this latter case the following series