4i8 SCIENCE PROGRESS 



was formulated at a time when the relationship of nerve fibres 

 to nerve cells was not so fully recognised as it is at present; and 

 the Wallerian doctrine may be accepted with confidence to-day. 

 It has, however, been questioned from time to time, and the 

 earliest to hold an opposite view was Vulpian. Vulpian, work- 

 ing with Philippeaux, cut nerves in young animals, excising 

 long portions so as to prevent the two ends uniting. Some 

 months later they were surprised to find that new perfectly 

 formed nerve fibres had appeared in the peripheral segment, and 

 that this segment possessed the physiological properties of being 

 excitable and capable of conducting nerve impulses. To this 

 phenomenon they gave the name of " autogenetic regeneration." 

 The publication of these results provoked a long controversy, 

 which lasted from 1859 to 1874, and was closed at the latter date 

 by Vulpian withdrawing his new idea. He did so because in the 

 meanwhile he had repeated his experiments more carefully, and 

 so discovered that, although the ends of the divided nerve had 

 not joined up, connection w^ith the central nervous system 

 had nevertheless been re-established by means of fibres growing 

 into the peripheral segment from other nerves cut through 

 in skin and muscle in the course of the operation. 



The controversy has been revived within the last few years, 

 and the position of the disputants has been almost exactly the 

 same as that occupied by Waller and Vulpian half a century 

 ago. Modern investigators have, however, the advantage of 

 being able to apply new methods of research, and are provided 

 with many histological reagents of which the older workers were 

 destitute. It is, however, never safe to argue entirely from 

 microscopic appearances, for nerve fibres may be simulated by 

 non-nervous structures, and a strand that looks like a nerve fibre 

 is not really such unless it can be experimentally shown to 

 be both excitable and capable of conducting nerve impulses. 



Vulpian's old doctrine of auto-regeneration has been revived 

 in this country by Ballance and Purves Stewart, and in Scotland 

 by Kennedy. The most prominent and persistent supporter 

 of the autogenetic theory is, however, a German neurologist 

 named Bethe. But none of these investigators have excluded 

 the fallacy which underlay the work of Vulpian and Philippeaux, 

 as has been recently pointed out by Langley and Anderson. 

 These two workers at first thought they also had obtained 

 evidence of purely peripheral regeneration, and it was not until 



