INTERNAL STRUCTURE OF CEREBELLUM. 527 



its upper and inner part. In whatever direction the section is carried 

 through the corpus dentatum, this waved line is seen, so that the dentate 

 body may be described as consisting of a plicated pouch or capsule of grey 

 substance open at one part and inclosing white matter in its interior, 

 like the corpus dentatum of the olivary body. White fibres may be traced 

 from it to the superior peduncles of the cerebellum and to the valve of 

 Vieussens. 



Fig. 359. VIEW OF A DISSECTION 

 OF THE FIBRES OF THE MEDULLA 

 OB LONG AT A AND PoNS VAROLII 

 (from Arnold). 



6, the anterior pyramid ; &', its 

 fibres traced upwards through, the 

 pons Varolii ; c, olivary column ; d, 

 olivary body ; m, superficial trans- 

 verse fibres of the pons on its left 

 side ; m', the deeper transverse 

 fibres of the right side; m", the 

 prolongation of these fibres as mid- 

 dle peduncle of the cerebellum ; 

 p, q, their continuation into the 

 laminse and folia of the cerebellum ; 

 n, inferior peduncle; x, the decus- 

 sating part of the left lateral 

 column crossing to the right ante- 

 rior pyramid. 



The fibres in the primary lamelke can be traced continuously from the peduncles of 

 the cerebellum. Upon these central plates are laid other collateral lamellae, which 

 are not connected with the fibres proceeding from the middle of the cerebellum, but 

 merely pass from one folium to another. 



The grey matter is not uniform throughout its whole thickness, but is composed of 

 two or more layers differing in colour and other characters ; resembling, in this 

 respect, the cortical substance of the posterior convolutions of the cerebrum. 



The fibres composing the peduncles of the cerebellum are arranged in its interior 

 in the following manner. The middle peduncles, which are the most superficial, enter 

 the lateral parts of the cerebellum ; they may be traced into the folia of those parts, 

 and form a large share of each hemisphere. The inferior peduncles pass upwards 

 into the middle part of the cerebellum, in the folia of which they are distributed, 

 especially in those of the upper surface. The superior peduncles, which are placed 

 nearest to the middle line, are principally connected with the folia of the inferior 

 vermiform process ; but a considerable number of them pass into or issue from the 

 grey capsule of the corpus dentatum which has been already described. 



A very different account from, that which has generally been received of the course 

 and relations of the tracts of nervous substance of the cerebellum has recently been 

 put forward by Luys, and deserves mention in this place. According to the statement 

 of this author, all the fibres of the cerebellar peduncles arise from the interior of the 

 corpora dentata ; the cells of those centres receive externally fibres from the laminated 

 periphery of the cerebellum, and internally give origin to the peduncular fibres ; the 

 fibres of the inferior peduncles of opposite sides cross the middle line and terminate 

 in the interior of the olivary nuclei ; and the fibres of the superior peduncles, likewise 

 decussating in the mesial plane before quitting the cerebellum, terminate in a grey 

 centre in the interior of the tegmentum of the crus cerebri, named by Luys the 

 superior olivary body. He further alleges that different fibres pass in all directions 

 from the superior and inferior olivary bodies, and that thus the fibres of the cerebellum 

 form a separate system indirectly connected Avith the fibres of the rest of the cerebro- 

 spinal axis. Only a short notice, however, of these views having as yet been published, 

 it will be necessary that the observations on which they are founded be made known 

 and fully corroborated, before statements of so startling a nature can be generally 

 accepted. (Luys, in Journ. de 1'Anat. et de Physiol., 1864, p. 225.) 



