MICKOSCOPIC STRUCTURE OF THE LAMINAE. 



91 



Of the fibres which pass from the white centre into the grey matter of the 

 laminas some, which have already been described, are the nerve-processes of the cells 

 of Purkinje. But others are derived from the medullated fibres of the white centre, 

 which appear to have two modes of termination in the grey matter. Some of these 

 white fibres traverse the granule-layer, and, branching within that layer, exhibit 

 peculiar moss-like appendages, both on their ramuscles and at the place whence these 

 come off ; they have on this account been termed by Eamon y Cajal the " moss- 

 fibres " (fig. 67, m). Each such fibre, with its ramifications, extends over a con- 

 siderable area of the granule-layer, but the 

 branching and moss-like efflorescences are 

 especially well marked near the level of the 

 cells of Purkinje, beyond which they pass 

 into the molecular layer, where they appear 

 to become longitudinal and horizontal, whilst 

 breaking up yet again into fresh branches. 



Fig. 68. SECTION OP CEREBELLAR LAMINA OF A 15-DAY KITTEN, SHOWING SOME OF THE NKUROGLIA 

 ELEMENTS. GOLGI'S METHOD. (Ram6n y Cajal. ) 



a, pia mater ; b, processes of the neuroglia-cells passing towards the surface where they end in 

 conical enlargements ; c, e, elongated neuroglia-cells ; d, stellate neuroglia-cell. 



Fig. 69. Two CELLS OF PURKINJE FROM THE CEREBELLUM OF A NEW-BORN PUPPY, SHOWN BY GOLGI'S 



METHOD. (Ramon y Cajal. ) 



A, cuticular layer of cerebellum with insertion of radial fibres. 



B, layer of superficial granules. 



C, molecular layer showing the longitudinal fibres derived from the granules of the next layer D 

 cut across and appearing as points. 



D, granule-layer. 



a, bodies of Purkinje's cells, the protoplasmic processes of which are still short and very irregular. 



b, nerve-fibre process of one of the cells ; c, d, two collaterals from the same fibre ; e, e, their 

 terminal arborisations in the molecular layer. 



The second kind of fibre from the medullary centre (fig. 67, a, e,f,g, fig. 70,.;', n, 0, s), 

 has been described by the same observer as passing towards the cells of Purkinje, 

 and enveloping their principal dendrites in a terminal ramification, or close plexus, 

 in the same manner that the bodies or bases of the cells and the commencement of 

 their axis-cylinder processes are enveloped in " baskets," formed, as we have seen 

 (p. 89), by the vertical branches of the nerve-processes of the inner cells of the 



