62 GRAY SUBSTANCE OF THE TRAPEZIUM, 



inner or anterior edge of the nucleus, a few fibres are seen turning off to enter the 

 large multipolar cells found here. This I have frequently observed in the sheep, 

 especially in preparations hardened by means of chromic acid, in vs^hich the course 

 of the fibres can be traced with great certainty. The majority of the fibres, how- 

 ever, pass onward and presently cross the roots of the facial, their further course 

 often becoming much obscured by these roots, as well as by the very numerous 

 bundles passing down from the cerebellum through the back of the auditory nucleus 

 and now radiating into the anterior network (Plate XVI, Fig. 44). I have, however, 

 several specimens from the medulla of the sheep, in which the entire course of the 

 root-bundle can be traced. It appears to be as follows : the bundle, after passing 

 along the anterior border of the nucleus, and sending a few fibres into its cells, as 

 stated above, bends around the nucleus, many of its fibres entering the large, stellate 

 and oval cells situated along the posterior margin. Some fibres penetrate more 

 deeply into the posterior part of the nucleus and enter cells. I have also thought 

 that I could trace a few fibres as far back as the groups of large oval cells lying 

 along the back of the auditory nucleus, and which are entered by the roots of the 

 posterior division of the auditory as well as by fibres from the cerebellum. Some 

 of the fibres from the sixth nerve certainly pass along the fioor of the fourth ventricle 

 for a considerable distance, but I was entirely unable to determine their ultimate 

 destination, as they are constantly united to the bundles derived principally from 

 the cerebellum, from which it is impossible to distinguish them. 



It would seem on theoretical grounds quite possible that there may exist, as stated 

 by Schroder van der Kolk, some connection between the nuclei of the abducens 

 and oculo-motor nerves, and that some of the fibres from the abducens, which are 

 lost sight of as they pass along the floor of the ventricle, may become ascending fibres 

 passing upward to the nucleus of the oculo-motor. The attempt to determine this 

 would, however, have carried me beyond the limits assigned to the present communi- 

 cation, and as I have been desirous to avoid anything approaching to theoretical 

 consideration I shall leave this point for future investigation. 



The cells in the posterior part of the nucleus, which are entered by the abducens, 

 are similar in appearance and size to those described in connection with the facial. 

 They are stellate, oval or fusiform in shape, and measure in the sheep, from -g J-^- 

 to X(\o of 'I'll iiich in diameter. 



