Ranson, Degeneration in Spinal Nerves. 267 



sents itself with striking uniformity (Vulpian '68-'69, Erlen- 

 MEYER '72, Hayem '76, Dejerine and Mayor '78, Hayem and 

 Gilbert '84, Friedlander and Krause '86, Dudley '86, Rey- 

 nolds 'Sy, Marinesco '92, Elzholz 'go, on human material; 

 and HoMEN '90, Vanlair '91, Pilcz '99, on animals). The mi- 

 croscopical changes are of some importance. The individual 

 fibers are much decreased in size, the change affecting chiefly the 

 myelin sheaths. Many of the fibers are entirely devoid of myelin 

 and there is a tendency for them to be grouped in bundles. These 

 altered fibers have been interpreted, sometimes as atrophied, some- 

 times as regenerated fibers; but the former interpretation seems to 

 be the better supported. Of the authors who have placed them- 

 selves on record with regard to this point, six regard the change as 

 an atrophy, while four believe that the altered fibers represent an 

 attempt at regeneration; and on the side of the majority are 

 included the two most thorough investigations: that of Fried- 

 lander and Krause ('86) recording eight cases of amputation, 

 and that of Homen ('90) recording experiments on more than 

 forty dogs. 



As a typical account of these alterations we may summarize the 

 description given by Friedlander and Krause ('86). In their 

 eight cases the nerve stumps presented patches of normal appear- 

 ance separated by areas entirely devoid of medullated fibers; still 

 other areas, constitutmg the larger portion of the cross-section 

 contained about half the proper number. In the atrophied bundles 

 the individual fibers are about one-third their normal size, and may 

 be recognized as faint retractile rings, which do not take the Wei- 

 gert stain. At the center of these rings a barely recognizable 

 point represents the remains of the axis cylinder. 



In addition to this simple atrophy there occurs in the proximal 

 portion of soitie of the severed nerve fibers a true degeneration, 

 not distinguishable histologically from Wallerian degeneration. 

 This may be seen in Marchi preparations from the central stumps 

 of experimentally resected nerves, removed twenty to forty days 

 after the operation (Redlick '93, Moschaew '93, Biedl '97). 

 Some observers have reported negative results with this stain; but 

 it must be remembered in this connection that the degeneration 

 in the central stump occurs about fifteen days later than true Wal- 

 lerian degeneration (Biedl '97, van Gehuchten '03), and that 

 the peripheral degeneration is at its height at a time when the 



