MICROSCOPIC STRUCTURE OF THE LAMINAE. 



89 



join with those of other cells, but have free terminations, often curling back for a 

 short distance before ultimately ending. 



Besides these dendritic processes of Purkinje's cells, the molecular layer con- 

 tains great numbers of very fine horizontal fibres, running longitudinally as regards 

 the laminae. These pass into the molecular layer from the small cells of the granule 

 layer. The axis-cylinder processes of the small " granules " in fact pass vertically 

 between the corpuscles of Purkinje and enter the molecular layer, where they join, 

 by a T- or Y-shaped junction, with one of the horizontal fibres just mentioned 

 (fig. 64, II.) ; these fibres may therefore be regarded as the branches of the axis- 

 cylinder processes of the granule-cells. They appear to end after a short course 

 either simply or by slightly ramifying. They are probably not medullated. 



The nerve-cells of the molecular layer are divisible, according to their relative 

 position in the layer, into two kinds, outer and inner. The outer cells, i.e., those 



Fig. 65. CELLS OP THE MOLECULAR LAYER OF THE CEREBELLUM. (Ram6n y Cajal. ) 



a, a cell from the outer part of the layer with a horizontally directed branched axis-cylinder process ; 

 6, nerve-fibre processes of cells which send processes c to aid in forming the basket-work d e around the 

 cells of Purkinje ; /, a process directed towards the surface of the lamina. 



in the outer half or so of the layer, somewhat smaller than the inner, have extensive 

 protoplasmic processes and an axis-cylinder process which extends for some distance 

 horizontally or obliquely in the layer, ramifying freely (fig. 65, a); its mode of ending 

 is somewhat doubtful. The inner cells, called also " basket "-cells, usually lie near the 

 cells of Purkinje, but they may be placed some little distance within the molecular 

 layer. Their protoplasmic processes pass in all directions, some of them even 

 reaching the surface of the organ ; the axis-cylinder process, which seems not to be 

 provided with a medullary sheath, usually emerges from the side of the cell and 

 extends laterally for some distance, giving off at intervals, as it passes along, a, 

 number of vertical branches which pass inwards towards the cell-bodies of Purkinje's 

 corpuscles, near which they become considerably enlarged (fig. 65, &, c). Having 



