514 S. WALTER RANSON 
it is probable that others of the independent fibrils within the 
old sheath have gained their independence by the degeneration 
of the fibrils which surrounded them. In the case of the non- 
medullated fibers the lateral branches with their end bulbs 
constitute the chief evidence of the reaction. One might assume 
that the appearance of the neurofibrillar reticulum was only 
a peculiar manifestation of degeneration. But the formation 
of new branches can only be interpreted as regenerative in char- 
acter and accepted as evidence that the axons live in the distal 
stump for some time after being severed from their trophic 
centers. Cajal (’08) places the same interpretation on these 
phenomena. 
Harrison (’08) found that, after cutting the nerves of the 
tail of the larvae of Rana sylvatica, the two cut ends of many 
nerve fibers had united by a protoplasmic bridge within one 
or two days. In these fibers the degeneration of the peripheral 
part of the axon was immediately arrested. These observa- 
tions find support in the evidence just presented to show that 
a portion of an axon severed from its trophic center continues 
to live for two or three days. 
While Cajal (08) and others, who have used his method in 
the study of the regeneration of nerves, saw and described the 
changes in the non-medullated fibers of the distal stump, just 
as they have been described here, they leave the impression 
that only a few scattering fibers are involved. They seem, 
also, to have overlooked the fact that exactly similar changes 
occur in the non-medullated fibers of the proximal stump. 
HARLY CHANGES IN THE PROXIMAL STUMP 
1. Changes in the non-medullated fibers 
The changes in the non-medullated fibers may be divided into 
three stages: (a) early abortive regeneration; (b) cellulipetal 
degeneration; (c) the formation of new axons. . 
a. Early abortive regeneration. By early abortive regeneration 
in the non-medullated fibers of the proximal stump we mean to 
designate a reaction exactly analogous to the abortive regen- 
