392 THE INTERMEDIATE PRIMATES 



longitudinal fiber bundles and it gradually assumes the characteristic 

 appearance of the reticular formation into which it merges. 



The Dorsal Sensory Nuclei 



The nucleus of the cohinin of GoII makes its first appearance in the 

 reconstruction as a prolongation from the central gray column, in close 

 proximity to the dorsal median septum. It rapidly assumes its maximum 

 ventrodorsal extent and proceeds upward as a gradually thickening mass of 

 gray matter maintaining its median position and separated from its fellow 

 of the opposite side by only a narrow encapsulation of white matter. 



Somewhat above the level of the appearance of the inferior olivary 

 nucleus, there appear scattered masses of gray matter in the column of 

 Goll, lateral to the main mass of the nucleus of the column of Goll. They 

 establish connection with the stem of the nucleus, which becomes somewhat 

 rounded in shape and then rapidly expands laterally. This expansion con- 

 tinues laterally until the dorsal extremity of the nucleus assumes a massive 

 appearance, occupying the major portion of the dorsal aspect of the oblon- 

 gata. It is somewhat arborescent in character, presenting masses of gray 

 matter broken up and surrounded by penetrating, longitudinally coursing 

 bundles of white libers. 



Cephalically, the nucleus of the column of Goll comes to rather an 

 abrupt termination and its most cephalic portion mesially forms part of the 

 caudolateral boundary of the fourth ventricle. Laterally it becomes sub- 

 merged from view by the appearance in this region of the nucleus of Deiters. 



The nucleus of the ct)Iumn of Burdach appears first as a rounded 

 mass of nuclear material in the dorsal portion of the reticular formation. 

 It is at this point encapsulated by fibers arising from the nucleus of Goll 

 and, passing ventrally in an arcade as the internal arcuate libers, gives 

 rise to the mesial fillet. Increasing in size and extending dorsallv at about 



