OF DENISOX UNIVKRSnv. ^j 



hypoolossus (XII) springs, with a rather large iuim!)er of fibres from the 

 lateral margin of the pyramids. 



The increase in the size of the m \{itlta from behind forward is 

 accompanied by an increase in the amount of gray matter, and also an 

 inter-reticulation of the gray and white matter. This reticulation is 

 the forward extension of the formatio reticularis of the cord. The 

 posterior cornua are divaricated cephalad, and between them are inter- 

 polated accessory gray masses, the corpus cuneato ^^ruci/c. The po.st£- 

 rior part of the dorsal cornu increases in size, forming the lub-iculum 

 RoJandii. In the anterior (ventral) cornua the lateral giant cells dis- 

 appear, but in the gray matter of the reticulum are very numerous me- 

 dium and small cells. Only in the higher (cephalad) regions of the 

 medulla do large multipolar cells (.08 mm ) reaj^jiear. 



In the caudal part of the medulla, near the |)yramidal decussation, 

 appear two groups of cells, the basal and lateral ninhi. Tnc fir>t is 

 rather broader than the pyramids, dorsal to which it lies, and extends 

 upward (cephalad) to about the middle of the medulla The cells 

 measure .016-. 02 mm., with nuclei .008- 01 mm. in diameter, and have 

 only obscure processes. This nucleus is divided into subordinate cell 

 clusters by numerous fibres passing in all directions, which evidently 

 have their origin here. The lateral portions of this nucleus are regu- 

 larly perforated by the roots of the hypoglossus. The second group 

 (nucleus lateralis), lies in the anterolateral (ventro-lateral) portion of 

 the medulla, extending a shorter distance ceijhalad. The cells are 

 multipolar with angular outlines and are of median size antl not closely 

 packed. Another cell cluster, iiiiclus centralis, lies on either side of 

 the ventricle audits cells are sjjindle shajjed and longitudinally placed, 

 measuring .024 mm. An additional cluster (hypoglossus nucleus), ex- 

 tending a shorter distance caudad and lying ventral to the above, con- 

 sists of multipolar cells .04 mm long, and retains its i)osition near the 

 ventricle, while the dorsal portion extends laterally toward the front. 

 A cell clustre in the corpus cuneato-^raiilc may receive the same name 

 and anteriorly nucleus rcstifonnc. Cejjhalad in the medulla, after the 

 termination of the basal nucleus, angular cells, .04 mm. in diameter 

 collect on either side of the raphe forming the nucleus of the raphe. 

 Cephalad from the nucleus lateralis, and distinctly separated fr(»m it, 

 is the nucleus of the' facialis, the cells of whi( h are multipolar, with 

 processes ascending to the root, and measure about .04 mm. 



The dorsal and lateral longitudinal bundles are indistinct, but a 



