548 Stewart Paton 



quite tbroug-li the ganglion to a point just below the ei)idernial 

 thickeniug-. It is quite uoticeable that around the group of large 

 pear-shape cells lying in the latero-ventral part of the mediilla 

 even more tibrils are differentiated than in the Acustico-facial area. 

 The intimate connections consisting of neurofibril buudles that unite 

 all the ganglionic masses, beginuiug with the Trigeminus and iu- 

 cluding the Vagus, are a very striking feature as is also the Splitting 

 up of the coarse fibril bundles into exceedingly fine filaments aljout 

 the latero-ventral group of cells from the Trigeminus through all 

 the sections to the caudal Vagus area. 



Even after passing the Glossopharyngeus this arrangement of 

 fibrils in the mednlla remains the sanie; three or four sections inter- 

 vening before the first roots of the Vagus are seen. The latter are 

 not so closely surrounded by cells as are the Glossopharyngeal 

 fibres, and may be easily traeed to the inner border of the epider- 

 mal thickening. As in the case of all the other epidermal thicken- 

 ings it is impossible to discover any fibrils among the nuclei of 

 this layer. The cranial bundles Coming from the Vagus may be 

 followed as they pass ventrally, frequently close under the epidermis 

 with which they seem, except at the points above meutioned, to 

 have uo connection. The caudal branches sweep forward in a curve, 

 until they reach that part of the mesenchyme lying between the 

 Oesophagus and epidermal plaque where they end abruptly. In no 

 instance bave I been able at this stage to detect the presence of 

 neurofibrils coming from the direction of the central nervous system, 

 either penetrating among the nuclei lining the alimentary tract nor 

 among those of the heart. Near the caudal end of the Vagus 

 area in the medulla we begin to meet with fibrils which pass out- 

 wards, at a point sliglitly dorsal to the exit of the ventral roots, 

 originally described by Balfour as "the questiona ble anterior roots 

 of the Vagus ou debatable border ground". 



Some of the fibrils in these bundles come from the large 

 latero-ventral group of cells, that from Trigeminus area on is 

 a prominent landmark, but others undoubtedly come from the 

 direction of the anterior commissure. For the present I shall not 

 discuss further their significance or origin nor their hearing upon 

 the question as to whether they are to be regarded as forming a 

 })art of the Hypoglossus or are the first of the ventral roots. As 

 DoiiRN has suggested they may be designated as occipito-spinal 

 nerves. These bundles pass directly outwards and on rcacliing 



