478 THE BRAIN OF MAMMALS, BY TH. MEYNERT. 



riorly situated fibrse arcuatse, which pass out from the corpus 

 restiforme, traverse the olivary body of their own side, and, 

 running behind the olivary body on the other side of the raphe', 

 enter, after junction with the large scattered cells, the posterior 

 column. 



Having entered the area of the posterior column, these col- 

 lected fasciculi undergo fresh interruption with cell clusters 

 which, enclosed by them in a plexiform manner, confer a peculiar 

 grained or striated (geflammten) appearance upon this area, and 

 divide beneath the floor of the fourth ventricle into two groups 

 that coalesce anteriorly the nucleus of the cuneate column and 

 the nucleus of the slender fasciculus (fig. 258, Cn, Or). The 

 cells of these nuclei are for the most part of small size (24 p in 

 length, and from 6 to 9 ju in breadth), while only a very well- 

 defined semi-circular mass of the outermost and most posterior 

 groups of cells found in the cuneate fasciculus consists of large 

 nerve corpuscles having a long diameter of from 30 to 36 ju, 

 and a thickness of 15-/i. 



The various directions pursued by the fibrae transverse proceeding 

 from the peduncle of the cerebellum, obviously associates them with 

 the projection-fasciculi descending in the tract of the tegmentum. And 

 it further appears that they are by no means merely in juxtaposition, 

 and without action upon one another, since they are connected by 

 the above-described clusters of small cells, by the olivary bodies, and 

 perhaps also by the scattered large cells. 



The relations that the interlacements above the superior olivsry body 

 and its region may have to the fasciculi of the spinal cord can scarcely 

 be estimated, since the morphological characters are still perhaps only 

 imperfectly known ; or, granting that they are understood, these tracts 

 also terminate in the cerebellum, which gives us no clue to the direction 

 in which they act as conductors. 



On the other hand, the interlaced fasciculi in the medulla oblongata, 

 which pass into the posterior column, clearly constitute a centripetal 

 tract, and their connection with the clusters (nuclei of the lateral column) 

 lying on the other side of the raphe would subject certain myelonal 

 fasciculi of the tegmentum to a here decussating reflex influence, just 

 as this tract is probably accessible to such influence proceeding from 

 the fifth nerve, both in its ganglia of origin and in the crus cerebri. 



We are equally justified in believing that certain fasciculi of the 

 projection- system which demonstrably pass from the crus cerebri into 



