542 S. WALTER HANSON 



maximuiu tliero is still a large number of normal axons, a number 

 far in excess of the nmul)er of surviving medullated fibers in the 

 same position in corresponding Pal-Weigert preparations. This 

 shows that some of the surviving axons in the medial half of the 

 degenerated tract of Lissauer represent endogenous non- 

 niediillated fibers. The absence of visible degeneration in the 

 lateral half shows that all or nearly all of the axons, non-medul- 

 lated as well as medullated, in the lateral half of Lissauer's tract 

 are endogenous. 



As seen in figures 4 and 5, the bundle L.t/ in the dor so-lateral 

 angle of the cuneate fasciculus, which has been separated from 

 the rest of the tract of Lissauer by the entering root, does not 

 undergo a complete degeneration. It degenerates to about the 

 same extent as the medial half of the tract of Lissauer, of which 

 it is a part. Occasionally, one sees bundles of axons running 

 forward to join the main part of the tract, as seen in figure 5. 

 The number of axons in this bundle in the dorso-lateral angle 

 of the cuneate fasciculus, and the number and size of the bundles 

 connecting it to the main part of the tract are much decreased 

 on the operated side in the segments affected. Like the medial 

 half of the tract, it is composed chiefly of dorsal root fibers. 

 The normal appearance of this bundle in the dorso-lateral angle 

 of the cuneate fasciculus of the fifth Imnbar segment of the cat's 

 cord is seen in figures 4 and 8 of a paper on Lissauer's tract in the 

 cat (Ranson '13). 



So far as the substantia gelatin osa Rolandi is concerned, there 

 was no appreciable decrease in the number of axons in its various 

 parts. This should not be taken to mean that the dorsal root 

 fibers of Lissauer's tract do not enter the substantia gelatinosa, 

 since the number of other axons there is so great that the loss of 

 these from the dorsal root does not make an appreciable difference 

 in the stain. 



