DEGENERATION AND REGENERATION OF NERVES 75 



by wandering cells which are common to both. An explanation 

 might be sought in the multiplication of the nuclei of the sheath 

 of Schwann and the resulting embryonic nerve fiber, which are 

 such marked characteristics of degeneration in the latter, while 

 being uniformally absent from the nerves of fowls showing an 

 early paralysis after a white rice diet. This is rendered still 

 more probable when it is remembered that in those fowls in 

 which paralysis was deferred — No. 17, G, and No. 9, G — tj^ical 

 embryonic nerve fibers were present and within these fibers de- 

 generated myelin occurred in only very small amounts or was 

 entirely absent. These two fowls differ from those showing pa- 

 ralysis at an earlier date in that in the former degeneration in 

 a certain proportion of the fibers had progressed to a later stage 

 than with those coming down at an early period. Were it possi- 

 ble to keep the fowl alive on the white rice diet till all fibers were 

 given opportunity to undergo advanced degeneration, I have no 

 doubt but that after regeneration in the same animal the med- 

 ullated nerve fibers would be quite devoid of even droplets of 

 degenerated myelin. 



In those fowls that have recovered from paralysis after 20 to 

 30 days on polished rice, the whole chain of e\'idence convinces 

 me that here degeneration is interrupted in the middle, as it 

 were; and regeneration is accomplished or superimposed without 

 passing through the later stages of degeneration. This being 

 the case, we must attribute the rapid removal of degenerated 

 myelin in sectioned nerves to the activity of the new nuclei of 

 the sheath of Schwann and the embryonic nerve fiber. This 

 assumption is further borne out by the well-known observations 

 that in meduUated fibers of the central nervous system in degen- 

 eration the globules of degenerated myelin persist for a very 

 long time. Halliburton ('07), in speaking of this point, says: 

 ''In situations like the central nervous system where the neuri- 

 lemma is non-existent, not only is the removal of degenerated 

 myelin a very slow process, but as is well known, regeneration 

 does not occur." Schroder ('08) points out, in speaking of de- 

 generation in medullated fibers of the cord: ''Noch nach einem 

 Jahr sind grobe Schollen sowie namentlich feine Tropfchen zu 



