The principles of physiology / by John Augustus Unzer ; and A dissertation on the functions of the nervous system by George Prochaska ; translated and edited by Thomas Laycock.

  • Johann August Unzer
Date:
1851
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Licence: Public Domain Mark

Credit: The principles of physiology / by John Augustus Unzer ; and A dissertation on the functions of the nervous system by George Prochaska ; translated and edited by Thomas Laycock. Source: Wellcome Collection.

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    ee es << nerve ; but that it is necessary that these impressions be more powerful. Hence we have an explanation, why the heart is so obtuse as regards sensation, and the stomach and intestine not acute, namely, because impressions made on the nerves of those parts do not penetrate the ganglia of the intercostal nerve to reach the brain, where the perception of sensations takes place. As regards the impressions, however obtuse they may be, that do reach the brain from the heart, stomach, and intestines, is it not rather that they reach the brain through the branches of the eighth pair distributed to those viscera, than that they pass through the intercostal [great sympathetic] ganglia? The conjecture is difficult. Further, the structure of the ganglia, as described by eminent inquirers, is not opposed to this doctrine of the functions of the ganglia, but if anything rather appears to confirm it. Meckel, Haase, and Zinn maintain,-that the ganglia are made up of the nerves entering into them, which divide into very minute filaments, so that they are variously subdivided, and make a sort of net-work. Condensed cellular tissue is intermingled with this net-work of nervous filaments, and the whole is enveloped in a somewhat tense external mem- brane ; whence may arise a somewhat gentle compression of the nerves entering the ganglion, which is sufficient to stifle, or rather intercept the less powerful impressions propagated along the nerves, and manifestly to obtund the more powerful. The whole of this doctrine, as to the uses of the ganglia, can how- ever be brought forward only as a conjecture not manifestly improbable, but meriting the investigation of the learned, and possibly containing a spark of truth, from which some acute genius may be able to produce greater light for us. He who shall unravel the uses of the ganglia will also give a reason why the fifth pair of cerebral nerves pass through the semi- lunar [Gasserian] ganglia, with the exception of a fasciculus and why only the posterior roots of the spinal nerves enter the ganglia, whilst the anterior roots pass by without any com- munication with them.’ Further, it may be asked, whether the external impressions made on the terminations of the nerves and passed onwards to 1 See my treatise ‘De Structura Nervorum,’ tab. 1i, figs. v, Vi. 2 Ibidem, tab. iii, figs. i, il.
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