254 PRACTICAL HISTOLOGY [XXXII 



nucleus of the 9th and 10th nerves (vago-glossopharyngeal 

 nucleus). 



Dorsally of the preceding a somewhat oval mass of grey 

 substance without obvious nerve cells the sensory nucleus of 

 the 9th and 10th nerves. 



The solitary bundle (descending vago-glossopharyngeal root) 

 a round bundle of small fibres ; it will be seen laterally of the 

 dorsal nucleus, more or less covered dorsally and at the sides by 

 curving bundles of fibres, it is not very obvious in this region, 

 and it may perhaps be better seen with oblique than with 

 directly transmitted light. 



The motor nucleus of the 9th and 10th nerves (nucleus 

 ambiguus), a small group of angular cells a little medially and 

 ventrally of the bulbar root of the 5th nerve. Fibres run from 

 it in the direction of the dorsal nucleus and of the solitary bundle. 

 It is not seen in every section. 



Root fibres passing from the region of the solitary bundle to 

 make their exit below or through the ventral edge of the bulbar 

 root of the 5th ; they are not seen in every section. The whole 

 of the 9th and 10th system is better seen in the next section. 



The solitary bundle and vago-glossopharyngeal nuclei are present 

 in the preceding section but are inconspicuous. 



The lower olive, a large folded lamina of grey substance, 

 with rather large elongated cells, dorso-laterally of the pyramid. 



The internal arcuate fibres, running chiefly from the base of 

 the posterior column nuclei, and extending through nearly the 

 whole of the lateral area; many are seen to decussate. 



In the lateral part of the grey reticular area, two large groups of 

 cells occur, the dorsal and ventral an tero -lateral nuclei. 



The accessory olive is present as a band dorsally of the pyramid 

 and stretching a short way up on the lateral edge of the white 

 reticular area. 



If a section is taken close to the extremity of the olive, the 12th 

 and 10th nuclei will be inconspicuous, and more fibres will be seen 

 passing on the medial side of the solitary bundle and decussating in 

 the anterior column tract. 



