MAMMALIAN. 59 



and may be traced inwards, winding among the cells of the nucleus, and apparently 

 becoming continuous with some of the cell-processes. This is especially the 

 case in the human medulla, where a very considerable portion of the fibres may be 

 traced, winding among the cells, and either joining them, or passing onward to 

 the raphe. In the sheep this is rarely to be seen, the fibres of the facial seemmg 

 to take a sudden bend just at this point, so that they are cut off quite abruptly by 

 the plane of section. A little higher up (Plate XVI, Fig. 44), the fibres of the facial 

 in the sheep, are seen to pass behind the nucleus, crossing over the roots of the 

 sixth nerve, some of them passing in front of the column of longitudinal fibres 

 (called by Stilling the constant root of the trifacial) ; others passing behind this 

 column to the raphe, where they decussate Avith those derived from the opposite 

 side ; a few may be traced into the nucleus. Still higher up, the whole bundle 

 may be traced inwards to this longitudinal column, where the central portion of the 

 root abruptly terminates, the outer fibres turning off behind and in front of the 

 longitudinal column, which is thus completely encircled by the roots which after- 

 wards pass onwards to the raphe. Those fibres, however, which reach the rapho, 

 seem to be few in number as compared with those which terminate abruptly in the 

 vicinity of the longituduial column, and even in the upper portions of the facial 

 course (Fig. 16"), where the whole bundle seems at first sight traceable to the 

 raphe, the number of bundles actually decussating or passing into the raphe, seems 

 so small when compared with the great thickness of the root, that I am inclined to 

 think that many of the fibres do actually turn downwards, passing down in the 

 longitudinal columns on each side of the raphe to the underlying nucleus, justifying 

 in this respect the conclusion of Stillmg. I have been confirmed in this supposition, 

 by frequently observing in the columns which Stilling has called the constant roots 

 of tlie trifacial and Schroder van der Kolk roots of the auditory, great numbers of 

 fibres obliquely cut across, which are especially noticeable in connection with the 

 abrupt termination of the facial roots just at this point, and I am inclined to con- 

 sider these columns as, at least, partial channels by means of which the upper 

 portion of the facial roots are conveyed downwards, either to the underlying nucleus 

 or to decussate below in the raphe. 



The greater part of the facial roots undoubtedly decussate at the raphe directly, 

 but I was unable to trace their farther course. It is not improbable, however, that 

 they may enter the nucleus of the other side, the celts of which are very numerous 

 on the side nearest the raphe, and send out many fibres in that direction. Schroder 

 van der Kolk is undoubtedly right in the statement, " that no other nerve of the 

 medulla oblongata has such an intimate connection with that of the other side, 

 whether directly or through the intervention of ganglionic cells, as. the facial."^ 



The cells of the fasciculus teres are very numerous in tlie sheep, filling a large 

 space between the roots of the facial and abducens. They are mostly oblong or 

 obovate in form, measuring about -gi-g to ^^^ of an inch in their longest diameter, 

 and send out their processes in various directions, mostly, however, either laterally 

 in the direction of the roots, or anteriorly towards the raphe, as well as longitudi 



^ Medulla Oblongata, HI. 



