Origin and Destination of Tracts in Medulla Oblongata. 73 



16. Vincent, Swale, ' Trans. Zool. Soc.,' rol. 14, part 3, No. 1, April, 1897 (in the 



Press). 



17. Vincent, Swale, ' Anat. Anz.,' Bd. 13, Eos. 1 and 2, 1897. 



18. Vincent, Swale, ' Birm. Med. Eev.,' Aug., 1896. 



19. Weldon, ' Quart. Journ. Hie. Sci.,' toI. 24, p, 171, 1884. 



20. Weldon, 1 Quart. Journ. Mic. Sci.,' vol. 25, p. 127, 1885. 



'• The Origin and Destination of certain Afferent and Efferent 

 Tracts in the Medulla Oblongata." By J. S. Risien Russell, 

 M.D., M.R.C.P., Research Scholar to the British Medical 

 Association, Senior Assistant Physician to the Metropolitan 

 Hospital, and Pathologist to the National Hospital for the 

 Paralysed and Epileptic, Queen Square, London. Com- 

 municated by Professor Victok Horsley, F.R.S. Received 

 February 18,— Read March 11, 1897. 



(Abstract.) 



In attempting to arrive at definite conclusions with regard to the 

 origin and destination of some of the afferent and efferent tracts 

 which exist in the medulla oblongata, the following experimental 

 procedures were adopted. 



1. Section or destruction of the lateral region of the medulla 

 between the ascending root of the fifth nerve and the inferior olive. 



2. Division of the restiform body. 



3. Division of the direct sensory cerebellar tract of Edinger. 



4. Severance of Deiters' nucleus from its connections with the 

 medulla. 



5. Section of the posterior columns and their nuclei in the 

 medulla. 



The first of these procedures w^as followed by degeneration of two 

 efferent tracts which could be traced throughout the whole length 

 of the spinal cord, the one occupying the antero-lateral region, and 

 the other being closely related to the crossed pyramidal tract, as 

 regards position. In addition to this, afferent fibres degenerate from 

 the seat of lesion, some of which pass to the cerebellum by way of 

 the restiform body, others course through the medulla and pons 

 external to the superior olive and on the ventral side of the emergent 

 roots of the seventh and fifth cranial nerves to eventually reach the 

 middle lobe of the cerebellum by way of its anterior peduncle. 

 Situated internally to the tract just described is another bundle of 

 more scattered fibres, close to the outer end of the fillet, with the 

 fibres of which system they remain intimately associated in their 

 further course towards the mesencephalon, and can be traced to the 

 region of the anterior corpora quadrigemina. Owing to destruction 



