502 S. WALTER RANSON 
the central or peripheral stump by itself, sometimes the two 
united stumps with the intervening scar. These large pieces 
of tissue were none too large, as the staining is perfect through- 
out. The use of such serial sections makes it possible to trace 
with certainty the course of the axons, but has involved the 
preparation of several thousand sections, and has precluded the 
use of other stains. 
The results of this investigation can best be assembled under 
the following headings: 
Early changes in the distal stump 
1. Degeneration of the medullated fibers and formation of nucleated pro- 
toplasmic bands 
2. Degeneration of the non-medullated fibers and the formation of nucleated 
protoplasmic bands 
3. Abortive autogenous regeneration in the distal stump 
Early changes in the proximal stump 
1. Changes in the non-medullated fibers 
Early abortive regeneration 
Cellulipetal degeneration 
Formation of new axons 
2. Changes in the medullated fibers 
Formation of a zone of reaction 
Fibrillar dissociation 
Early branching of the axons in the immediate neighborhood of the 
lesion 
Formation of lateral branches at some distance above the lesion 
Formation of fiber bundles and skeins 
Mechanism of the regeneration of nerve fibers 
1. Proliferation of axons in the central stump 
2. Penetration of the new axons through the scar 
3. Utilization of the protoplasmic bands as pathways for the new axons in 
the distal stump 
EARLY CHANGES IN THE DISTAL STUMP 
1. Degeneration of the medullated fibers and the formation of 
nucleated protoplasmic bands 
Leaving out of account, for the moment, the interesting meta- 
morphoses of the nerve fibers which occur in the distal stump 
in the immediate neighborhood of the cut surface during the 
first three days, we confine ourselves in this section to the changes 
