NERVOUS CENTRES. (THEIR MICROSCOPICAL ANATOMY.) 



709 



freely intermingle. The anterior and posterior 

 pyramids and the restiform bodies consist, at 

 least in great part, of longitudinal fibres, but the 

 remainder of the fibrous matter appears to be 

 made up of transverse or oblique fibres. Most 

 of these are doubtless connected with the roots 

 of the many nerves which arise from the me- 

 dulla oblongata. Stilling refers to special ac- 

 cumulations of vesicular matter connected with 



the roots of each nerve, and which probably 

 form its proper origin. These contain large 

 vesicles. It is impossible to give an exact in- 

 terpretation to all the parts which are seen by 

 his method of examination, imperfectly defined 

 as they are from the use of such low mag- 

 nifying powers. It would be waste of time 

 and space to do more than refer to the repre- 

 sentation given by Stilling (fig. 397) of the 



Fig. 397. 





"ii 



555=3^ .'. : , ' T / 







Transverse section of the medulla oblongata through the lower third of the olivary bodies. (From Stilling.) 



Magnified ten diameters. 



a, anterior fissure ; 6, fissure of the calamus scriptorius ; c, raphe ; d, anterior columns ; e, lateral 

 columns ; f, posterior columns ; g, nucleus of the hypoglossal nerve, containing large vesicles ; h, 

 nucleus of the vagus nerve ; i, i, gelatinous substance ; k, h, roots of the vagus nerve ; I, roots of the 

 hypoglossal, or ninth nerve ; m, a thick bundle of white longitudinal fibres connected with the root of 

 the vagus ; n, soft column ( Zartstrang, Stilling) ; o, wedge-like column ( Keelstrang, Stilling) ; p, trans- 

 verse and arciform fibres ; q, nucleus of the olivary bodies ; r, the large nucleus of the pyramid ; 

 s,s,s, the small nuclei of the pyramid ; u, a mass of grey substance near the nucleus of the olives 

 ( OHven-Nebenhern) ; u,q,r, are traversed by numerous fibres passing in a transverse semicircular 

 direction ; v, w, arciform fibres ; x, grey matter near the root of the vagus. 



structure, as viewed by a magnifying power of 

 ten diameters. Nothing can be more true to 

 nature, so far as it goes, but its correct explana- 

 tion must be sought for by diligent investigation 

 with high powers. Numerous bloodvessels pe- 

 netrate the central matter of the medulla, and 

 no doubt many of the lines, which Stilling 

 supposes to represent fibres, are in reality ves- 

 sels passing to the grey matter. 



The mesocephale has very much the same kind 

 of structure as the medulla oblongata; trans- 

 verse fibres (those of the pons) at its anterior 

 part, longitudinal ones just behind these (pyra- 

 mids), with vesicular matter freely intermixed. 

 Its posterior part is the same in structure as 

 the optic thalamus, and consists of numerous 

 fibres with an abundant quantity of grey matter. 

 The inferior layer of the crus cerebri is purely 

 fibrous; its superior portion is identical in 



structure with the optic thalamus, and the locus 

 niger contains large caudate nerve-vesicles, 

 with a considerable quantity of pigment con- 

 tained in them. 



Microscopic investigation has as yet thrown 

 no light on the direction and connections of the 

 fibres of the cerebrum or cerebellum. What is 

 known upon these points is derived from coarse 

 dissection. The tubular fibres of which the 

 white matter is composed, appear to be dis- 

 posed on different planes, and perhaps inter- 

 lace with each other, so as to render it difficult 

 to isolate any plane to any great extent. This 

 arrangement is more obvious in the cerebellum 

 than in the cerebrum. The grey matter of 

 both these segments contains the ordinary ele- 

 ments, caudate and spherical vesicles; but in 

 the cerebellum those of the latter variety are 

 much larger and more distinct than those which 



