Insanity / by G. Fielding.

  • Blandford, G. Fielding (George Fielding), 1829-1911
Date:
1897?]
Catalogue details

Licence: Public Domain Mark

Credit: Insanity / by G. Fielding. Source: Wellcome Collection.

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    a large number of small pyramidal cells with apical processes which end in tufts in the superficial layer. Collaterals are given off from those apical processes and also from the axis-cylinder process. The lateral expansions are numerous, extend for long distances, and end without anastomosing in similar expansions of other cells. The third layer, the zone of large pyramids, resembles the second, except in the size of the cells which are known as giant cells. These cells may be divided into two classes: those with short apical processes which do not pass into the superficial or molecular layer but terminate deeper, and those with long apical processes which always reach up to and end in the superficial layer. The fourth layer is a zone of polygonal cells, egg-shaped, spindle-shaped, or triangular. The apical proc- esses of these cells do not reach the superficial zone, and the collat- erals of the axis-cylinder process either end in terminal ramifications or form a plexus round some of the nerve fibres of the white medul- lary substance. Of the cells entering into the constitution of these layers Andriezen enumerates eight types: (1) The pyramidal with long apical process; (2) the pyramidal with short apical process; (3) the ambiguous which may be bicornate, globose, fusiform; (4) the granule cell; (5) the fusiform, with ascending axis-cylinder process; (6) the fusiform with descending axis-cylinder process; (7) the oblique and the inverted pyramidal; and (8) the polygonal with short branching axis cylinder. Ramon y Cajal is of opinion that the psychical functions are inseparably associated with the presence of the pyramidal cells, be- cause as we ascend in the animal series these bodies become larger and larger and more complicated. He is also of opinion that these pyramidal, or, as he calls them, “psychical” cells, may exercise their functions more fully and more usefully the greater the number of the collateral expansions of their axis cylinder, and the more copious, broad, and ramified their lateral and basal expansions, which have no anatomical connections and must therefore transmit impressions by contact. There is an advance in complexity as we ascend from the reptilian to the mammalian brain, and that which has been described as the mixed pyramidal or polymorphic system of cells with short apical expansions is not found in the reptile. The order of progress is this: “We have first an increase of cortical grey expanse, until in man there is much complexity and depth of convolution of the grey substance. There is an increase in the development of the corpus callosum and an increase in the whole cerebral mass, both absolutely and relatively to the rest of the encephalon, from the lower mammals up to the higher mammals and man. The white matter of the cere-