So S. WALTER RANSON 
the end of the distal stump, nor in the protoplasmic bands. 
Their absence in this case, twenty-five days after the operation, 
although well developed protoplasmic bands are present, and 
their presence in other specimens, fourteen and nineteen days 
after the operation when the protoplasmic bands are only in- 
completely formed, speaks strongly against their development 
in situ in these bands. Moreover, in both the fourteen- and 
nineteen-day specimens, nerve fibers from the central stump 
had reached the distal stump through the scar. 
Probably the most instructive preparations, however, are 
those from Dog vu, killed thirty-four days after the removal 
of 1 em. of the sciatic nerve. A study of serial sections shows 
that the scar covering the distal stump is devoid of nerve fibers 
except in one very limited area—here there are a few fibers. 
All of the protoplasmic bands in this specimen are devoid of 
new axons except a few in that part of the distal stump over- 
laid by the innervated portion of the scar. Here a few of the 
bands can be seen containing sharply staining axons. Figure 
28 shows five bands in this location, down one of which a new 
axon is growing. The axon can be seen to end in an enlarge- , 
ment directed distally. The presence of a few of these sharply 
staining axons in protoplasmic bands adjoining the only part 
of the sear which contains nerve fibers, while all the rest of the 
bands are empty, is a strong point in favor of their growth into 
the distal stump from central fibers. The presence of end bulbs 
like the one seen on the fiber in figure 28 is evidence in the same 
direction. 
Cajal lays stress on the occurrence of branching in the axons 
in the protoplasmic bands. Such branching has been observed 
occasionally in these preparations, but its value as an evidence 
of the down-growth of the axons seems to the present writer 
not to be very great. 
In Dog vit, killed thirty-four days after section of the sciatic 
with primary suture, great numbers of fibers from the scar run 
into the distal stump. Several axons often run down one pro- 
toplasmie band. Figure 29 represents a cross section of this 
distal stump. At a is seen a large protoplasmic band (formed 
