RECONSTRUCTION OF TARSIUS SPECTRUM 141 



being reduced to a mere slit between the mesial surfaces of the reticular for- 

 mation extending backward to the central gray matter. The reticular for- 

 mation on its lateral aspect forms a support for the substantia gelatinosa of 



FIG. 65. LATERAL SURFACE OF THE GRAY MATTER OF THE BRAIN STEM, 



TARSIUS SPECTRUM. 



Key to Diagram, interped. gray matter, Interpeduncular Gray Matter; Nuc. clava, Nucleus Clava; 



Nuc. CUN., Nucleus Cuneatus; font. Nnjc, Pontile Nucleus; ret. form.. Reticular Formation; sub. gelat. 



TRIG., Substantia Gelatinosa Trigemini; sub. nig.. Substantia Nigra; ven. gray col.. Ventral Gray Column. 



Rolando which lies in a bed excavated from its lateral surface. Dorsally the 

 reticular formation is in close relationship with the central gray matter 

 forming the floor of the fourth ventricle, the dorsal surface of the reticular 

 formation supporting the central gray matter throughout its entire lateral 

 extent. 



The reticular formation in the oblongata presents no definite special 

 nuclear collections on its surface with the exception of the inferior olivary 

 nucleus and the substantia gelatinosa of Rolando. At the junction of the 

 oblongata with the metencephalon, the ventral surface of the reticular for- 

 mation becomes irregular and recedes from the surface, giving place to the 



