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518 S. WALTER RANSON 
in the sciatic involved only a limited cellulipetal degeneration. 
While, of course, the usual axonal reaction must have occurred 
in the small cells, these did not degenerate. The spinal ganglia 
associated with the injured sciatic nerve in Dogs vir and vItt, 
killed thirty-four days after the operation, and Dogs rx and x, 
killed twenty-five days after the operation, were prepared by 
the pyridine-silver method. In these ganglia the small cells 
and their associated non-medullated fibers were apparently 
as numerous as in normal ganglia, although, since no counts 
were made, it would be impossible to be sure that none had 
degenerated. The non-medullated fibers in the ganglia and 
adjacent portion of the nerves stained in a perfectly normal 
manner, showing that they were not involved at that level in 
a cellulipetal degeneration. Another piece of evidence, show- 
ing that the cellulipetal degeneration in the neighborhood of 
the lesion did not involve the degeneration of the entire neurone, 
is found in the subsequent regeneration of these fibers. 
c. Formation of new axons. On the fourteenth day the ma- 
jority of the non-medullated fibers in the proximal stump are 
still m the late stages of degeneration. They appear as light 
yellow, delicate bands, closely resembling the early stages of 
proteplasmie band formation, in the distal stump. There are 
present, however, on the fourteenth day, many sharply stained 
black fibers in the bundles of light yellow ones. One bundle, 
in which the regenerative changes have gone particularly far, 
is seen in figure 13. In a bundle of sharply staining fibers one 
sees five end bulbs, three directed toward the periphery, p, 
and two towards the center, c. From this time on there is a 
constantly increasing number of sharply staining black fibers 
in these bundles. On the nineteenth and twenty-fifth days 
there are numerous end bulbs and an increasing number of 
fine black fibers. After thirty-four days the bundles of non- 
medullated fibers in the last centimeter of the proximal stump 
are larger and more compact than in the normal nerve; and 
these bundles can be traced, in longitudinal sections, out of 
the cut end of the nerve into the sear. <A cross section of the 
stump taken a short distance above the cut at this time shows 
a great increase in the number of these fibers (fig. 26). 
