PAPIO O'NOCEPHALUS 309 



the ventromcdian sulcus may be seen some ot the crossing bundles of the 

 pyramidal system and also some bundles prior to decussation (Pyx). A 

 large mass of gray matter adjacent to the ventral gray and apparently 



FIG. 145. BABOON. LEVEL OF CAUDAL EXTREMITY OF NUCLEUS OF BURDACH. 



CB, Column of Burdach; cen, Central Gray Matter; CG, Column of Coll; dt, Deiterso-spinal Tract; fle. 

 Dorsal Spinocerebellar Tract; cow, Ventral Spinocerebellar Tract; hel, Spino-olivary Tract of Helweg; nb. 

 Nucleus of Burdach; ng, Nucleus of Goll; nr, Nucleus of Rolando; py. Pyramid; Pi'x, Pyramidal Decussa- 

 tion; REF, Reticular Formation; rst. Rubrospinal Tract; spt. Spinothalamic Tract; trd. Descending Tri- 

 geminal Tract; ven. Ventral Gray Column; xpv. Crossed Pyramidal Tract. [Accession No. 150. Section 25. 

 Actual Size 12X8 mm.] 



continuous with the substantia gelatinosa as well as the nucleus of Burdach, 

 is the griseal portion of the reticular formation ( Ref). Surrounding the 

 reticular formation are the fibers constituting the intermediate medullary 

 substance, and, upon the periphery of this area, the circumferential zone. 



