Scientific American Supplement, No. 520, December 19, 1885Various
Science
Scientific American Supplement, No. 520, December 19, 1885
Various
Science -- Periodicals
Tuczek and Fuchs have confirmed the discoveries of Exner, that there are
no medullated nerve fibers in the convolutions of the infant, and
Flechzig has developed this law, that "medullated nerve fibers appear
first in the region of the pyramidal tracts and corona radiata, and
extend from them to the convolutions and periphery of the brain," being
practically completed about the eighth year. This fact is of practical
importance in nervous and mental diseases, since it is becoming an
admitted truth that the histological changes in disease follow in an
inverse order the developmental processes taking place in the embryo.
Hence the recent physiological division of the nervous system by Dr.
Hughlings Jackson into highest, middle, and lowest centers, and the
evolution of the cerebro-spinal functions from the most automatic to the
least automatic, from the most simple to the most complex, from the most
organized to the least organized. In the recognition of this division we
have the promise of a steadier and more scientific advance, both in the
physiology and in the pathology of the nervous system.
Mr. Victor Horsley has recently demonstrated the existence of true
sensory nerves supplying the nerve trunks of nervi-nervorum.
Prof. Hamilton, of Aberdeen, claims that the corpus callosum is not a
commissure, but the decussation of cortical fibers on their way down to
enter the internal and external capsules of the opposite side.
Profs. Burt G. Wilder, of Ithaca, and T. Jefrie Parker, of New Zealand
Institute, have proposed a new nomenclature for macroscopic encephalic
anatomy, which, while seemingly imperfect in many respects, has, at
least, the merit of stimulating thought, and has given an impulse to a
reform which will not cease until something has been actually
accomplished in this direction. The object being to substitute for many
of the polynomial terms, technical and vernacular, now in use, technical
names which are brief and consist of a single word. This has already been
adopted by several neurologists, of whom we may mention Spitzka, Ramsey,
Wright, and H.T. Osborn.
Luys holds that the brain, as a whole, changes its position in the
cranial cavity according to different attitudes of the body, the free
spaces on the upper side being occupied by cerebro-spinal fluid, which,
obeying the laws of gravity, is displaced by the heavier brain substance
in different positions of the body.
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