The Lower I'urtioii of Ihc JIiiiikui Jiniln-Slcin. \'.] 



furrow. A more detailed description of these projections has been given in 

 the subdivision descrilMnji the anterior cohunn. 



On the ri<i;lit side of this model, the spurs of nuclear material between 

 the hber bundles and the outer limits of the gray matter have been modeled. 

 This results in a slight fenestra in the wax, marking the crossing of the 

 l)yramids, while the great area of the decussation is occupied by the network 

 of nuclear material which lies between the fiber bundles. Such a picture of 

 the network is shown in figure 9. When this right side is viewed laterally, 

 the most striking feature is the fulness of this surface as compared with the 

 left. Following the dorsal margin of the anterior column cephalad, it is 

 seen to extend dorsally in the caudal portion of the pyramidal crossing f:)y a 

 series of step-like dorsal projections. It very soon fuses with the formatio 

 reticularis ventral to the substantia gelatinosa. From this point cephalad, 

 the extreme lateral wall of gray matter is solid, and exhibits certain charac- 

 teristics dependent upon the level considered. The mesial surface of this 

 dorsal projection from the ventral horn is very rough and irregular, marked 

 by the outlines of the coursing jjyramidal fibers (figure 9). Inspected from 

 the ventral surface (figure 1), the right side shows marked irregularities in 

 its dorsal concavity in the region of the decussation, as well as marked 

 lateral bowing of tlie anterior column in this region. Above the dccussatio 

 pyranndum, tlie anterior i:)ortion of this gray matter of the formatio reticu- 

 laris becomes markedly widened transversel}\ From the marked ventro- 

 mesial border, the mesial surface slopes dorsally toward the mid-line without 

 irregularities. The mid-line ventral projection is not marked. 



As soon as the anterior column becomes united to the ventral svu-facc 

 of the formatio reticularis, its lateral surface becomes marked by irregulari- 

 ties. A poorly defined ridge with a sharp dorsal border continues the line 

 of the dorsal margin of the anterior column for a short distance cephalad. 

 Dorsal to this are two short irregular ridges which deviate to the substantia 

 gelatinosa. Just above the ventral of these three ridges is the rounded 

 caudal shoulder of an elevation which runs cephalad, to exjiand suddenly 

 as the nucleus olivaris inferior develops in its midst (figure 1). A short 

 distance caudal to the oliva, between this eminence and the substantia 

 gelatinosa, is a well-defined lateral ridge, broad and smooth, which is traced 

 cephalad to a point slightly caudal to the cochlear nucleus. Behind this 

 eminence are the irregularities of the nucleus of Blumenau and around on 

 the dorso-lateral surface is the smooth ])late of gray matter which leads pos- 

 teriorly into the tela choroidea inferior (figure 3). 



The relations of the nucleus oli^aris inferior to the formatio reticularis 

 are of interest. The anterior column, after merging with the formatio 

 reticularis and losing its motor cells, becomes increased in the transverse 

 and dorso-ventral diameters (figure 1), showing a sudden enlargement just 

 caudal to the nucleus olivaris inferior. On the mesial surface of this enlarge- 

 ment the caudal end of the nucleus olivaris accessorius medialis develops. 



