The plan of the central nervous system : a thesis for the degree of Doctor of Medicine in the University of Cambridge / by Alex. Hill.
- Alexander Hill
- Date:
- 1885
Licence: Public Domain Mark
Credit: The plan of the central nervous system : a thesis for the degree of Doctor of Medicine in the University of Cambridge / by Alex. Hill. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![brain, the nucleus lenticularis, is or is not connected with the overlying cortex from which it is separated (at the seat of origin of the supposed connecting fibres) by less than a quarter of an inch. The huge mass of fibres composing the corpus callosum is by some anatomists supposed to consist of transverse com- missural fibres between the hemispheres only—by others to be restricted to the fibres of decussation derived from the crura cerebri. If after all the time and labour which have been devoted to microscopic investigation of the brain such discre- pant opinions are possible, it is time that this method as well as naked-eye observation was treated with the utmost distrust, and recourse was had to fundamental morphological and physio- logical considerations to obtain a conception of the plan of structure of the system. Originating as an involution of the epiblast, the tubular character of the primitive central nervous system is the key to the position. Although the tube is dilated in the anterior region (fig. 1), this character is recognisable throughout its whole extent. The first differentiation, which occurs in the tube, results in its separation into three concentric parts, of which the inner becomes the epithelium of the central canal, the middle, what I propose to call the CENTRAL GREY TUBE, and the outer, the conducting matter of the white columns. Fig. 1. Fig. 2. Fig. 3.* [In fijiurcs 3—11 the cclU of anterior horn are marked by the large cross, of la teral horn by the large cross with dots, of visceral horn {Clurkc's column) by the small cross, of posterior horn by dagger.] The sequence of the changes by which this grey tube is converted into the several cell groups has not been satisfactorily I](https://iiif.wellcomecollection.org/image/b22299683_0012.jp2/full/800%2C/0/default.jpg)
