122 C. WINKLER. THE CENTRAL COURSE 



cervicalis it does suffer great alterations. (Plate XXI fig. 25 M O). 

 The dorsal obtuse edge, tending towards the lateral horn disappears 

 and when the tract has reached the thoracic cord its much reduced 

 diagram (Plate XVII fig. 21 D 4 D 8 D 12 ) has the form of a seg- 

 ment, lying at the peripherical antero-lateral margin and the issuing 

 anterior roots pass between its degenerate fibres. In the luinbo- 

 sacral intumescenfia the edge towards the lateral horn reappears, 

 now situated more medially and going along the roots. (Plate XVII 

 fig. 21L 4 ,S 2 ). 



In this way the tract of DEITERS may be traced (Plate XVII fig. 21, 

 Plate XVIII fig. 22 F. G. Plate XXI fig. 25 M O) into the 

 sacral cord, providing the antero-lateral horn with degenerate col- 

 laterals, but leaving the greater part of its fibres in the cervical 

 cord, and giving more fibres to the intumescentiae than in the 

 thoracic part of the cord. 



For tracing the two tracts of DEITERS, MAncm-method excels 

 above all other methods, but it remains in perfect accordance 

 with them. 



The myelinisation-method in the new-born or elder foetus of 

 rabbit is very appropriate to demonstrate the beginning of the 

 descending tract, its relation to the facial root and the facial nucleus 

 and rootfibres, and its curvation into the longitudinal axis (Plate 

 I fig. 5. Plate XIII fig. 18 E and F). 



In that stage it is medullated there among other non medul- 

 lated fibres. But in the medulla it becomes more difficult to trace. 



GUDDEN'S method, as employed by von MONAKOW, has demonstrated, 

 that after hemisection of the lower oblongata or in the cervical 

 part of the cord, all the large cells in the nucleus of DEITERS 

 disappear. In this case , like in that of the fillet-section with loss of 

 the large cells in the tuberculiun acusticurn , there is demonstrated 

 a total retrograde atrophy from a system lesioned not too far from 

 its origin. 



But by MARCHi-degeneration after the section of the dorsal 

 systema more is shown. 



In the beginning of their course , the fibres of the ascending 

 and descending roots of the N. VIII are intermingled with those of 

 the tracts of DEITERS in such a manner, that it is impossible to 

 judge, whether the transverse dorsal fibres, now degenerated in a 

 most intense degree take their origin in the nucleus of DEITERS 

 or in other nuclei from the dorsal systema. 



Some of those degenerate transverse dorsal fibres may be 

 traced through the raphe, through the fasc. longitud. posterior, 



