lissauer's tract 535 



gin are situated distally, that is, in the spinal ganglion. These 

 experiments confirm in this respect the results obtained by a 

 histological study of the dorsal roots and their ganglia (Ran- 

 son '12). 



There are no points of interest in connection with the degenera- 

 tion in the posterior funiculus. These phenomena have been so 

 often described that it would be a waste of space to discuss them 

 here. Figure 1 shows the degeneration which had occurred in 

 the sixth lumbar segment 74 days after the sixth and seventh 

 lumbar roots had been tied off on one side. Figure 3 shows the 

 degeneration which had occurred in the seventh lumbar segment 

 20 days after cutting the sixth and seventh lumbar roots. 



Although the degeneration in the posterior funiculus has been 

 repeatedly described in great detail, I have not found in the liter- 

 ature a satisfactory account of the changes in Lissauer's tract 

 following lesions of the dorsal roots. The recorded observations 

 may be summarized as follows: Nageotte ('03) reported a case in 

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

 up to and including the fourth lumbar, without causing any 

 degeneration of the medullated fibers of Lissauer's tract. 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 degenerating fibers within the spinal cord. Most of these 

 investigations fail to demonstrate any changes in the tract of 

 Lissauer, which has, in fact, received very scant consideration 

 (Darkschewitsch '96; Frohlich '04; Kopczynski '06; Margulies 

 '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). 



As shown in figure 3, degeneration of the dorsal roots was 

 accompanied in our experiments by a degeneration of medullated 

 fibers in the medial half of Lissauer's tract. In this region degen- 

 erated medullated fibers were clearly evident in Marchi prepara- 



