98 S. WALTER RANSON 



the axon content of the entering rootlets apparently established 

 the correctness of the observations of Lissauer and Bechterew, 

 and these have accordingly been generally accepted. 



The usual account which is given of this tract is that it is 

 formed of fine, rather sparsely arranged, medullated fibers, which 

 enter the spinal cord from the dorsal roots. There is good reason 

 to believe, however, that this account of the origin of these fine 

 medullated fibers represents l)ut half of the truth, since many of 

 them seem to be of endogenous origin. The evidence in regard 

 to this point has been presented in a previous paper (Ranson 

 '13), and need be only briefly summarized here. 



Nageotte ('03) was the first to assert that the medullated 

 fibers of Lissauer's tract were of endogenous origin. He reported 

 a case in which a tumor involved all the nerve roots in the cauda 

 equina up to and including the fourth luml^iar without causing 

 any degeneration of the medullated fibers of Lissauer's tract. 

 The presence of an apparently normal number of intact fibers 

 in this case shows conclusively that many, probably a majority, 

 of the medullated fibers of this tract are of endogenous origin. 

 It can not be taken as conclusive proof that none of the medul- 

 lated hbers in this tract are derived from the dorsal roots. Many 

 human cords, in which extensive degeneration of the dorsal roots 

 had resulted from tumors, syphilis and other causes, as well as 

 the cords of animals in which some of the dorsal roots had been 

 divided, have been studied with the object of tracing the degen- 

 erating fibers within the spinal cord. Most of these investiga- 

 tions, although showing extensive degeneration in the posterior 

 funiculus, show no changes in the tract of Lissauer (see the 

 papers of Darkschewitsch '96, Frolich '04, Kopczynski '06, Mar- 

 gulies '96, Orr '06, Wallenberg '98 and Zappert '98). A small 

 amount of degeneration in Lissauer's tract after lesions of the 

 dorsal roots has been seen by Collier and Buzzard '03), Laignel- 

 Lavastine ('08), Sibelius ('05) and Sottas ('93). 



The observations of Lissauer and those of Nageotte are dia- 

 metrically opposed to each other. But, in view of the finding 

 of a limited amount of degeneration in Lissauer's tract following 

 lesions of the dorsal roots, it mav be safelv said that both are 



