THE MEDULLA OBLONGATA. 



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ventrally (to the nerve-centers). This bundle — fasciculus longitudinalis 

 dorsalis of Schiitz — lies in the bnlb between the vagus center and the 

 •eminentia teres. It may he traced as far upward as the corpora quadri- 

 gemina, where it passes under the fibers of the gray matter stirrounding the 

 aqueduct of Sylvius. 



In Fig. 240, a representation of the hypoglossal center, Koch, to whom 





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- NuAeua XII. 







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Fig. 240. — Frontal section through the nucleus of the hypoglossal 

 nerve. (After Koch.) 



we are indebted for our knowledge of its net-work, has well-shown its wealth 

 of fibers and cells. Ventral from the center are a few cell-groups (Roller's 

 hypoglossal center), from which, however, no hypoglossal fibers arise. 



The pyramidal crossing was discovered as early as 1710 by Frangois Petit. The 

 olives were first described by Vieussens. Macroscopic differences in the development 



