324 Mr. A. A. Gray. A Ganglion in the Human [Nov. 26, 



therefore, if present in the human subject, would probably lie embedded in 

 bone. The second difficulty lay in the fact that the structures in the 

 region involved do not have the same relationship to one another in the 

 human subject as in the sheep. The stapedius muscle, for example, lies 

 below, internal to, and in front of the facial nerve in man, not above it as 

 in the sheep. 



The plexus which was seen in the sheep had a position a little below the 

 lower termination of the stapedius muscle, and internal to the facial nerve. 

 Since the stapedius muscle has, so to speak, been rotated downwards and 

 inwards in man, as compared with the position which it occupies in the 

 sheep, the most likely place for the plexus would be a little below the 

 lowest point of the origin of the stapedius muscle. This clue was followed, 

 and, as will be shown later, the inference was justified by the result. 



The petrous portion of a human bone was removed in the fresh state and 

 a small piece, including the region indicated above, was decalcified and 

 prepared for microscopic section. The preparation, after very complete 

 decalcification, was embedded in celloidin, and sections in the vertical plane 

 were made from before backwards. The sections were stained with iron-alum 

 and ha;matoxylin. 



The series of sections was not complete, but it was quite sufficient to 

 reveal the existence of a plexus, corresponding to that of the sheep, but 

 very much smaller in size. Owing to the incompleteness of the series it 

 cannot be definitely stated what is the exact origin of all the bundles which 

 go to compose the plexus, but it is clear that they are derived from at 

 least two sources : first, the facial nerve ; second, the auricular branch of 

 the pneumogastric. 



While it was interesting to discover this plexus in man, a much more 

 remarkable fact was also revealed. This was the presence of a com- 

 paratively large ganglion associated with the plexus, and, like it, embedded 

 in bone. The first impression on finding this ganglion was that it was a 

 portion of one of the ganglia of the glossopharyngeal or pneumogastric 

 nerves. But closer examination showed that this could not be the case, 

 because it was at a considerable distance from the trunks of these nerves, 

 and, moreover, it was embedded in bone. 



A further search was then made among the writer's macroscopic pre- 

 parations of the temporal bone, and the ganglion was discovered to be present 

 in it also. It is shown in Plate 6, fig. 1, which is taken from the writer's 

 text-book on ' Diseases of the Ear.' It will be seen that the ganglion, g.g., lies 

 immediately below the inferior termination of the stapedius muscle, and 

 about the same distance in front of the facial nerve in the vertical portion 



