526 S. WALTER RANSON 
part in the ultimate regeneration of the nerve fibers. It is our 
purpose in this section to trace the steps in the formation of 
the regenerated axons, restating briefly those observations 
already mentioned which are of significance in the final process 
and linking them together in a coherent whole. 
1. Proliferation of axons in the central stump 
On the first day after the lesion some of the axons grow out 
into the exudate and break up into many branches (fig. 16). 
Others on the first day give off fine branches from their surface 
within the sheath in the immediate neighborhood of the lesion 
(fig. 17), some of which find their way into the exudate. Thus, 
from the end of the first day on, fine nerve fibers, which are 
demonstrably branches of the medullated axons of the proximal 
stump, are present in the developing scar. The chief contri- 
bution to the new axons, which enter the scar from the cut end 
of the proximal stump, comes from the branching of the old axons 
at a somewhat later date (fig. 20). These side branches from 
the medullated axons are given off chiefly in the last 5 mm. of 
the proximal stretch; and, while a few are formed as early as 
the eighth day, they are constantly increasing in number to 
the thirty-fourth day. Running for the most part within the 
sheath of the old axon from which they arose, they arrange 
themselves into fascicles of parallel threads (fig. 24, a) when 
their course toward the periphery is direct, and into tangled 
skeins (fig. 24, b) when for any reason they fail to grow directly 
toward the periphery. Some idea of the enormous number of 
such branches can be obtained from a study of cross sections 
of the proximal stump just above the lesion (fig. 25). Thus 
within the space formerly occupied by one fiber there may be 
fifty or even more. These bundles of fine fibers, derived as 
branches from the old medullated axons, run compactly until 
they leave the old sheath and plunge into the scar. Here they 
scatter out in every direction. Some of these fibers never reach 
the scar but turn backward in the proximal stump. Where- 
ever it is possible to see these fibers ending within the thickness 
of a section they are tipped with a bulb. 
