RECONSTRUCTION OF PAPIO CYNOCEPHALUS 



339 



reached, where it increases rapidly in size, thus becoming the main mass of the 

 pontile tegmentum. It is irregular in its surface outhne, being indented by the 

 dorsal surface ot the inferior oHvary nucleus and the dorsal accessory 



FIG. 158. LATERAL SURFACE OF THE GRAY ^LATTER OF THE BRAIN STEM, 

 PAPIO CYNOCEPHALUS. 



Key to Diagram, dors, cochl., Dorsal Cochlear Nucleus; inf. coll.. Interior Colliculus; inf. olive, Inferior 

 Olive; L.\T. GEN. BODY, Lateral Geniculate Body; meso-gen. body. Mesial Geniculate Body; nucl. of 

 BuRDACH, Nucleus of Burdach; nucl. of deiters. Nucleus of Deiters; pontile. Pontile Nuclei; ret. 

 form., Reticular Formation; subst. gel. Rolando, Substantia Gelatinosa of Rolando; subst. nigra. 

 Substantia Nigra; sup. coll., Superior Colliculus; vent, cochl.. Ventral Cochlear Nucleus. 



nucleus, laterally by the substantia gelatinosa trigemini and dorsolaterally by 

 the base of the nucleus of Burdach and the beginning of the vestibular area. 



Alcove the inferior olivary nucleus the reticular formation shows the 

 elfect of the developing trapezoid body by presenting a relatively deep exca- 

 vation on its ventral surface close to the midline, in which the main mass of 

 the trapezoid body lies. 



Laterally the reticular formation is in contact with the substantia 

 gelatinosa trigemini and above the level of this nuclear mass it presents a 



