HUMAN AND MAMMALIAN. 3J 



the summit of the antero-lateral column, and passing through the most anterior and 

 largest cells, sends forward a series of returning loops, first through the antero-pos- 

 terior bundles along the inner border of the caput cornu posterioris, and then in 

 succession through the network of the lateral column as it makes its way towards 

 the raphe ; but in this course its fibres lie side by side with those which have been 

 already described as proceeding from the antero-lateral column to decussate 

 through the raphe with their opposite fellows, so that it becomes almost impossible 

 to identify them and ascertain if they share in the decussation; that they do so, 

 however, is rendered extremely probable by the fact that in birds all the fibres of the 

 eighth pair of nerves, of which the highest correspond to the glossoplmryngeal, may 

 be distinctly seen to decussate through the raphe, after passing through and around 

 their nuclei."^ 



In the cat the course of this anterior bundle is very distinctly seen, and I have 

 several specimens showing the anterior division as it passes along the margin of the 

 nucleus towards the raphe, where it decussates with a similar bundle from the other 

 side. As the bundle turns forwards at the apex of the nucleus, it gives off a few 

 fibres which enter among the cells, some of which they undoubtedly join, and in its 

 course along the border of the nucleus, a few fibres are seen at intervals turning 

 inwards towards the deeper lying cells, while on the putside of the bundle fibres 

 constantly turn ofi", forming loops or joining the numerous radiating fibres which 

 everywhere penetrate the anterior and antero-lateral columns ; a part of these pass 

 across the anterior columns to the raphe with some of the radiating fibres, but most 

 of them are soon lost sight of, and probably pass upwards with the longitudinal 

 fasciculi. A portion of the middle roots may be traced forwards, as stated by 

 Clarke, to the group of large ceUs occupying the place of the fascicuhiH teres and 

 representing the continuation of the hypoglossal nucleus ; and fibres are also seen to 

 turn off from the anterior bundle towards the same group. 



In the cat the decussation at the raphe is very distinct, quite as much so as in 

 the case of the vagus ; but in the sheep and especially in man, I have had much 

 difficulty in tracing the course of the anterior bundle, for the reasons which Clarke 

 has given in the passage quoted above. In the cat, however, the entire course of 

 the glossopharyngeal roots is very distinct and easily made out. 



In Plate IX, Fig. 33, the upper roots of the glossopharyngeal may be seen pass- 

 ing through the caput cornu in the medulla of the cat. Plates II and XIV, Figs. 

 8, 8", from the sheep, and Plates VI and XV, Figs. 24, 24", from the human meduUa, 

 also illustrate the course and appearance of the glossopharyngeal roots. 



Schroder van der Kolk has supposed that a connection exists between the trifacial 

 and glossopharyngeal, from the fact that the latter passes through the caput, but as 

 in the case of the vagus, I have found no evidence of any direct communication 

 between the glossopharyngeal roots and the bundles which descend through the 

 caput from the fifth nerve. 



» PWlos. Transactions, 1858, 255. 



