104 HENRY O. FEISS 
At the end of two to three months, the sections showed the per- 
manent histological characteristics of the lesion. These were 
either cavity spaces or scar, or both. The cavity spaces were 
sometimes sharply circumscribed, and occasionally their outlines 
corresponded to the original outlines of the grey matter. In gen- 
eral, it seemed that the amount of scar depended on the amount 
of direct injury to the pia and dura, and the size of the cavity- 
spaces on the extent of the original destruction of cord substance, 
although of course, the extent of the original cavities could not 
be completely judged on account of tissue repair. In some places 
the grey matter showed marked distortion of outline, suggesting 
contraction. 
As to signs of nerve regeneration in the cord, one occasionally 
saw among the débris and granulation tissue small fibers with 
faint coats of myelin. But of course, there was no way of telling 
whether these indicated repair; if they ‘did it could have been 
slight only. 
In all stages, one saw striking changes in the ganglion cells of 
the gray matter, near the lesion. These consisted in alterations 
in size, shape and staining, reactions as well as chromatolysis and 
vacuolation. 
Inferences from the above 
Judging from the histological condition one could divide the 
anatomical appearances into two stages, roughly corresponding 
to the two stages in the clinical improvement. It seemed likely 
that the early improvement was partially due to the removal of 
tissue débris, because the cavities became apparent about that 
time. Also as shown clinically, by the swelling about the wound, 
there was at first marked fluid exudate, the absorption or escape 
of which was undoubtedly a factor in that improvement. 
As to the more gradual improvement that supervened in most 
of the cases, disregarding the anatomic evidence of repair of nerve 
tissue in the cord itself, as being too slight to explain the marked 
restoration of function, there are four other explanations to be 
considered: (1), actual regeneration of nerve fibers in roots and 
peripheral nerves; (2), vicarious activity of nerves and muscles 
