lissauer's tract in the cat 263 



ably in part fibers directly out of the dorsal roots which have not 

 had a previous vertical course in the cord, and in part the hori- 

 zontal continuation of the vertical fibers. 



Although there is no septum separating the fasciculus cuneatus 

 and entering root zone from Lissauer's tract, the border between 

 the two is represented by a very sharp almost straight line ; and 

 the contrast between the closely packed large medullated fibers 

 of the one and the more scattered fine medullated fibers of the 

 other is very striking. On the lateral side the tract is separated 

 from the lateral funiculus by a rather thick and very constant 

 pial septum (not present in man). This pial septum never quite 

 reaches the substantia gelatinosa; and ventral to this septum 

 there is no sharp line of separation between this tract and the 

 adjacent portion of the lateral funiculus. Lissauer's tract seems 

 to extend laterally upon the dorsal surface of the substantia 

 gelatinosa, its fine scattered medullated fibers gradually giving 

 place to more thickly packed large ones. 



This gradual transition between the ventral part of Lissauer's 

 tract and the lateral funiculus attracted the attention of Lesz- 

 lenyi ('12) who made a very elaborate comparative study of Pal- 

 Weigert preparations of the spinal cord of mammals, birds and 

 reptiles. He saw many oblique fibers in the transition zone 

 between the tract of Lissauer and the lateral funiculus; and con- 

 cluded that many of the vertical fibers of Lissauer's tract come 

 from the lateral funiculus through this transition zone. But the 

 evidence which he presents in his paper, and the observations 

 which I have been able to make on the cord of the cat, do not 

 seem to me to show anything more than that there is an inter- 

 mingling of the fibers of Lissauer's tract with those of the lateral 

 funiculus ventral to the pial septum. 



Leszlenyi states that in all the cords he examined, with the 

 possible exception of the human cord, the dorsal root fibers enter 

 the posterior funiculus in such a way that one may be sure that 

 no considerable number find their way into the tract of Lissauer. 

 This seems to agree with 'the findings of Waldeyer ('88) on the 

 cord of the gorilla, where few, if any, fibers could be traced from 

 the dorsal roots into Lissauer's tract. Leszlenyi finds, in all, four 



