1906.] 



Regeneration of Nerves. 



263 



from these two points of view that he has attacked Bethe's position, and it 

 certainly appears on a priori grounds exceedingly improbable that meso- 

 blastic cells should be capable of giving rise to such a highly specialised 

 structure as an axis cylinder, which so far as is known is exclusively 

 epiblastic in origin. 



We may, however, now pass from the region of speculation to consider 

 briefly a few typical researches dealing with the facts of regeneration, before 

 describing our own observations. 



The propositions maintained by Waller,* namely, the integrity of the 

 central end of a cut nerve, the degeneration of the peripheral segment, and 

 its regeneration by fibres growing out from the central stump, were 

 questioned a few years later by Vulpian and Philippeaux.f These observers 

 cut nerves in various, but mainly, young animals, excising long portions to 

 prevent reunion with the central end. Some months later they were 

 surprised to find that the peripheral ends had regenerated and were 

 excitable ; to this phenomenon they gave the name of " autogenetic regenera- 

 tion." These results were regarded with great scepticism by most writers,t 

 until, in 1874, Vulpian§ repeated his experiments, and obtained the same 

 results as before. This time, however, Vulpian put forward a new explana- 

 tion and, in fact, accepted the Wallerian doctrine, because he found that 

 connection with the central nervous system had been re-established by 

 means of fibres growing into the peripheral stump from other nerves in the 

 neighbourhood. He had also, with Philippeaux, observed regeneration in 

 portions of nerve trunks transplanted under the skin of the abdomen, and 

 explained this in 1874 in the same way. 



In the revival of the controversy that has taken place within the last few 

 years the position of the disputants has been almost exactly the same as 

 that occupied by Waller and Vulpian more than half a century ago. 



Ballance and Purves Stewart|| hold the view that the new nerve-fibres 

 have a peripheral origin, but rely exclusively on histological evidence ; one 

 method they employed was G-olgi's, which can hardly be considered for this 

 purpose a trustworthy one. It is well known that black streaks are 

 produced by this method by structures which are not nervous at all. A 



* " Nouvelle methode anatomique pour l'investigation du systeme nerveux," ' Comptes 

 Rendus,' 1852 ; " Experiences sur les sections des nerfs," ' Gazette Medicale,' 1856. 



t " Note sur les experiences demontrant que les nerfs separes des centres nerveux . . .," 

 etc., ' Comptes Rendus,' 1859. 



\ See, for instance, Ranvier, ' Legons sur l'histologie du Systeme Nerveux,' 1873, 

 pp. 158, 186, and 190. 



§ ' Archives de Physiologie,' 1874, p. 704. 



|| Loc. cit. 



