492 S. WALTER RANSON 
allowed to unite, Bethe (’03) decided to follow the example of 
Philipeaux and Vulpian (’59) and determine what would occur 
in a nerve fully cut off from its central connections. He worked 
with the sciatic nerve of young dogs and to prevent the union 
of the cut ends he adopted special operative procedures: (1) 
In some dogs he grasped the sciatic nerve at the great sacro- 
sciatic foramen, tore it out along with the motor roots and 
spinal ganglia and cut it off in the middle of the thigh. (2) In 
others he cut the sciatic in the middle of the thigh, left the 
peripheral stump in place, cut off 3 em. from the central stump 
and thrusting it through one muscle, sewed it into another. 
At that time he considered the second method as reliable as 
the first. In these ways he believed that he had effectually 
excluded the possibility of any union between the central and 
peripheral stump; and in carefully conducted autopsies he was 
unable to find any trace of such connection in those cases which 
he considered successful. Also physiological evidence of the 
absence of connection between the central and peripheral ends 
was obtained at autopsy in the absence of reflex movements 
on stimulating the distal stump and the absence of movement 
in the muscles innervated by the sciatic nerve on stimulation of 
the central stump. 
Under these circumstances, which seemed both anatomically 
and physiologically to exclude the possibility of any union with 
the central nervous system, Bethe obtained evidence of regen- 
eration in the peripheral stump. Many medullated fibers were 
present. Stimulation of the peripheral stump caused contrac- 
tion in the muscles of the leg but no reflex movements. He 
also noticed that some time after autogenous regeneration had 
occurred a slow degeneration set in which caused, after a time, 
the complete disappearance of all regenerated fibers. This 
Bethe considers an important point in favor of the autogenous 
nature of their regeneration, since, he assumes, fibers which 
have formed central connections do not undergo a second degen- 
eration. In his somewhat limited study of the development 
of these autogenously regenerated fibers he distinguishes five 
stages: (1) protoplasmic band formation; (2) differentiation 
