]^^i-. 11 Zentralblatt für Physiologie. 315 



bar nerve, and in the anterior root of the 3'*'^ thoracic nerve. The 

 fibres reached the lower roots by some unknown course, since de- 

 generation was only found in a short stretch of the upper thoracic 

 sympathetic. In the spinal cord there was degeneration in the direct 

 cerebellar tract from the 7*^ C. to the 5**^ L. segment. The de- 

 generation varied from segment to segment, but in some segment 

 or other, it was found in the anterior column, at the junction of 

 the anterior and lateral column, in the region of the pyramidal tract 

 and in the medial dorsal part of the posterior column. 



Mich all ow in this case refrains from drawing conclusions as 

 to the course of the nerve fibres. But one conclusion may safely 

 be drawn — viz that by the method used, there may be degenera- 

 tion, or apparent degeneration of nerve fibres which have no^ con- 

 nection with the nerve fibres cut. 



I have referred to this experiment since the degeneration which 

 follows section of the cervical sympathetic is probably better known 

 to most readers than that which follows section of the rami com- 

 municantes. But the method employed was the same throughout, 

 and the other results are equally grotesque. Michailow finds that 

 the sympathetic of one side sends fibres into the spinal cord by 

 way of the anterior and of the posterior roots, and that the fibres 

 continue their course in various tracts in all three columns of the 

 cord, generally of both sides. If fibres take this course, section of 

 the nerve roots must cause at least as much degeneration in the 

 tracts of the spinal cord as is caused by section of the sympathetic 

 fibres. The observations which have been made on the section of 

 the nerve roots when care has been taken to avoid injury to the 

 cord, show that section of the anterior roots causes no degeneration 

 in the columns of the cord, and that section of the posterior roots 

 causes little, if any, columnar degeneration except in the homo- 

 lateral posterior column and in Lissauer's tract. 



Even if it be allowed that after section of both roots a few 

 fibres degenerate outside the limit of the posterior column and 

 Lissauer's tract, there is still no doubt that the section does not 

 cause the degeneration described by Michailow, and that the 

 degeneration in bis cases must be due to other causes than section 

 of the sympathetic nerve fibres^). It may be noticed also that 

 Michailow in some of his figures marks degeneration in the po- 

 sterior roots without any degeneration in the posterior root zone 



1) I may recall that I have given reason to belleve that the sympa- 

 thetic ganglia send some post-ganglionic flbres to the blood-vessels of the 

 cord by way of the nerve roots. These however are not column flbres and 

 do not end in connection with spinal cord cells; further they arise only 

 from the ganglia in the neighborhood of the cord segment and do not de- 

 generate in the lower thoracic and lumbar region in consequence of any of 

 the nerve sections performed by Michailow. They can be foUowed by teas- 

 ing; whether this degeneration can be seen by the Marchi method de- 

 pends on whether the post-ganglionic flbres are medullated, or not. In the cat 

 and rabbit hardly any are medullated, even early in their course; and so 

 far as I have seen, the same is the case in the dog. 



