Lectures on diseases of the nervous system : delivered at Guy's Hospital / by Samuel Wilks.

Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on diseases of the nervous system : delivered at Guy's Hospital / by Samuel Wilks. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    corresponding effect is seen on the muscles by an influence conveyed back by the motor nerves. We have now a higher class of animal which can be excited to movement by an external stimulus. Now, bear in mind that we also have this system, the spinal or excito-motor, in common with the lower animals, and do not ignore it because we have still some further development of our nervous centres. Thirdly, imagine the vertebrae developing into a skull case at the same time that the spinal marrow itself expands and terminates in two large ganglia, known as the central ganglia of the brain—the head-centres, or the thalami optici and corpora striata. These are the termini which become subsequently influenced by higher powers acting upon them, and through them on the whole spinal cord; but whether they possess other properties, independent of those of the cord, I cannot, from my own clinical experience, posi- tively declare. It is believed, however, that an animal possessing these bodies has a sensorium, and a kind of perception, and thus, when these are stimulated, evinces what are styled emotions ; that a human being in possession of these structures, without any further cerebral development, might display, for example, such emotions as laughing or crying. I think myself that these are merely reflex actions and that the ganglia are nothing more than the superior terminations of the cord which come immediately under the in- fluence of the cerebral hemispheres. Fourthly, suppose, proceeding from these bodies which constitute the upper part of the cord, a number of white fibres passing towards higher ganglia, and we have still another system. These ganglia in a mass form the cineritious part of the brain, a region where fresh sensations are received and fresh powers are developed. This is the largest mass of grey nei-vous substance in the body, and would form a layer as large as this table, were it not folded up so as to be packed in a small compass. Herein the sensations con- veyed from the surface of the body, and from the special senses, become to the recipient as perceptions and ideas: the animal has become a reasoning being. The power here produced reacting on the body is spoken of as the will, and the animal has become a voluntary agent. The amount of reasoning power and the strength of volition depend, I bave no doubt, mainly upon the development of the cerebral hemisphei-es—small but not absent in the lower animals, most perfect in such a splendid head as that of the late Surgeon Lawrence or of the first Napoleon. The quality of the brain, however, or its texture, no doubt varies considerably, and thus some idiots have had enormous heads. You perceive, then, that the machinery of the body is worked or