Ixii Journal of Comparative Neurology. 



undergo a shrinkage after the severance of the peripheric nerve or its 

 roots, but cannot decide with which of the roots they are connected. 



8. The group of cells which supplies the muscles of the back with 

 motor fibres, occupies the medial and anterior horn, which is in accord- 

 ance with the views of Kaiser and Collins respecting the function of 

 this group. 



In conclusion I wish to recommend warmly Nissl's method of 

 staining as a valuable addition to the methods in use for the investiga- 

 tion of the central nervous system. For the study of the finer struc- 

 ture of ganglionic cells it is much superior to the nigrosine, carmine 

 and similar stains. This superiority is due to the fact stated by Nissl, 

 that the hardening with the chromsalts damages the structure of the 

 cells, for which reason fine cell changes will easily escape observation. 



Degenerations of Sensory Tracts in the Spinal Cord.^ 



Dogs were experimented upon by cutting the dorsal roots of one 

 side, in one case of the lumbro-sacral plexus, in another case of the 

 four last dorsal nerves. In the former case the dog was kept ahve 33 

 days, in the latter two months and a half. The spinal cord was treated 

 by a modification of Marchi's method. 



1 . In the portion of the cord corresponding to the six sensory 

 roots cut from the lumbro-sacral plexus the degeneration is conspicuous 

 in both the white and the gray matter. In the former it extends also 

 to the dorsal columns of both sides, to the direct cerebellar tracts of 

 both sides, to the white and gray ventral commissure, a few to the ven- 

 tral columns, and a still smaller number to the intra-meduUary fibres of 

 the ventral roots. In the grey matter degeneration is noted in the en- 

 tering fibres of the dorsal root, in the transverse section of the longitu- 

 dinal fibres and of the fibres running between the base of the dorsal 

 cornu and the centre of the grey matter, and in the nerve cells, not a 

 few of which are atrophied, some granulated and some disappeared. 



2. In adjacent regions cephalad the degenerative process is 

 always conspicuous in the dorsal columns, limited, however, to the in- 

 ternal portion of the columns of Burdach and Goll. It is equally con- 

 spicuous in the direct cerebellar tracts, especially in the dorsal part. 

 Few degenerate fibres are seen in the ventral columns, and they are 

 rare in the ventral commissure. It is never observed in the intra-med- 

 ulary fibres of the dorsal or of the ventral root. In the grey matter 



' Paladino, G. Gli effetti della recisione delle radici sensitive del midollo 

 spinale e la loro interpretazione. Annali di Nevrologia, XIII, 1-2, 1895. 



