660 



tliere often cells of a smaller type. Very shortly, in a more ventral 

 region than where the fii'st XII pells had occurred and medially 

 from there a fourth group of cells^ appears, so that a large complex 

 is formed, shaped like a slanting quadrilateral, containing 70 — 90 cells. 

 Here we can clearly distinguish a venti'O-medial, a ventro-lateral, a 

 dorso-medial and a dorso-lateral group. In many sections a few cells also 

 occur in the centrum, while in all there are numbers of cells between 

 the tongue nucleus and the dorsal motor vagus nucleus. Not un- 

 frequently an actual bridge exists between tlie two nuclei (nucleus 

 intermedins, fig. 16). Slightly more frontally both nuclei strike against 

 the raphe and 168 sections spinally from the calamus a few XII 

 cells appear in the raphe, whereupon a nucleus commissuralis hypo- 

 glossi makes its a])pearance (fig. 17). In this region many central 



J ' i ■*■ i 



. >\. *^/. ; .. i . 



Fig. 17. 



cells appear in the irregular quadrilateral tongue nucleus. The com- 

 missural tongue nucleus does not seem to follow any continuous 

 course, in a few consecutive sections it is present. Everywhere the 

 connecting cells are met "with between the tongue nucleus and the 

 adjacent vagus nucleus. Now the XII nucleus begins to diminish in 

 size, it becomes loose in structure, and shows gaps at different 

 places, only the latero-dorsal and lateroventral portions remain 

 constant, even commissural cells are now and again seen and not 

 unfrequently the bridge to the dorsal motor vagus nucleus is com- 

 plete. Then the central cells disappear entirely, and the latero-ventral 

 portion also diminishes, so that it is mainly only the latero-dorsal 

 part , and the cells connecting with the vagus nucleus which are 

 still properl)»^ visible. More frontally, more XII cells again appear and 

 the irregular quadrilateral gradually reappears though in a less marked 



