Literary Notices. Ixi 



ter can hardly be recognized. In later stages of the degeneration the 

 differentiation of the various parts becomes lost. 



3. The character of the retrogressive changes is determined. 



a. By the distance of the point of lesion from the cell. 



b. By the character of the cell, or more probably by the manner 

 of its connection with the severed fibres. 



In '' motor" cells severance of the motor fibre near origin from the 

 cell (section of the anterior root) is followed by the acute changes, viz. 

 by homogeneous transformation of the cell. 



Lesion of the motor fibre at a considerable distance from the cell 

 effects as a rule the gradual changes, that is, a gradual shrinkage of the 

 cell ; but occasionally, as the case of amputation reported by Kahler 

 and Pick proves, also here the changes in the " motor" cells may have 

 the character of homogeneous degeneration. 



In the cells of Clarke's columns, in the small cells situated at the 

 base of the posterior horns, and in those of the lateral horns the changes 

 always bore the character of the gradual shrinkage, no matter whether 

 the nerve (larger distance), or the roots (small distance) was severed. 

 Here the manner of the connection between the severed fibre and the 

 cell which undergoes the change is less intimate than the connection 

 between "motor" cell and motor fibre, as the latter is the principal 

 part of the neuron of which the " motor " cell forms the centre. 



4. The gradual shrinkage gives probably much more chance for 

 recovery of the cell, if the continuity of the severed nerve fibre can be 

 restored, than the homogeneous degeneration. 



5. The small cells situated at the base of the posterior horns along 

 the course of the nerve bundles, which pass from the ventral part of the 

 posterior columns towards the lateral columns, are intimately connected 

 with the posterior roots. Part of these cells are connected with poste- 

 rior root fibres of the same side, part with posterior root fibres of the 

 opposite side. This connection probably consists in close contact of 

 the terminal branches of the posterior root fibre with the network into 

 which the axis cylinder of the altered cell dissolves itself; nothing pos- 

 itive can be stated in that regard, however, without examination by 

 Golgi's or Ramon y Cajal's method. The latter makes no mention of 

 said cells. 



6. The cell group of Clarke's columns is in connection with fibres 

 of the posterior roots both of the same and opposite side. 



7. Of the cells of the medial zone (Waldeyer's " Mittelzellen"), 

 and of the small cells of the lateral horn, I can only state, that they 



