MIXUTE STRUCTUEE. 



521 



tiguous with the corpuscles of Purkinje, contains some nerve fibres 

 parallel to the surface. 



Fig. 366.— Structure op Cortex Fig. 366. 



OP Cerebellum (from a clra\nng 

 by Mr. H. E. 0. Sankej). 



a, pia mater ; h, external laj-er ; 



c, layer of corpuscles of Purkinje; 



d, inner or granule layer; c, me- 

 dullary centre. 



The inner layei', " granule 

 layer," (fig. 366 d), next the 

 medullary centre, consists of 

 granule-like corpuscles which 

 lie in dense groups, in a gela- 

 tinous matrix, containing a 

 plexus of fine nerve fibres. 

 The corpuscles vary in size 

 from 4:oVoth to the ^iiy^th of 

 an inch, the larger being less 

 densely scattered around the 

 corpuscles of Purkinje. Some 

 are round, others angular, 

 and possess a protoplasmic 

 envelope with processes, sup- 

 posed to be connected with 

 ilie plexus of fine nerve fibres, 

 among which they lie. 



The cells of PurJcinje (c) lie 

 in a single layer, between the 

 outer and inner layers of the 

 cortex. Their distance apart 

 is greater on the sides than 

 at the apex of the convolu- 

 tion. Some are irregular in 

 shape, but many are flask- 

 shaped, their long axis being 

 at right angles to the sur- 

 face ; the diameter of the 

 larger cells is the -o^oth to 



-j-ij\joth of an inch ; each contains a spherical nucleolated nucleus. Pro- 

 cesses extend from them into both the outer and inner layers : the outer 

 process is much the larger, and is granular or finely striated in texture, 

 it divides usually near the cell, and its branches, either at once or after a 

 short horizontal course, pass towards the surface, dividing repeatedly. 

 Some are apparently connected with the angular corpuscles of this 

 layer, but most can be traced almost to the outer surface, and are there 

 lost. They have been said to turn back and end in the granule layer. 

 The inner process is fine, undivided, and passes into the granule layer. 

 It is supposed to be continuous with the axis cylinder of a nerve fibre. 



The medullary centre, consists of nerve fibres arranged in parallel 

 or interlacing bundles, which pass off on each side and form the central 



