TRAUMATIC LESIONS. 383 
while the direct fibres degenerate at the peripherical end, the recurrent-- 
fibres remain intact and keep up a certain sensibility in a region which was 
supposed entirely anesthetized. The theory of preserved sensibility took. 
the place temporarily of that of the returned sensibility and for a time nervous:. 
regeneration was considered as the appanage of youth. It is scarcely:- 
ten years since a most distinguished surgeon contested again the regenera-.. 
tion of nerves, and affirmed that, even in making the suture of both ends, 
the nervous current was unable to pass through the cicatrix. He said, if : 
sensibility is not entirely abolished, the fact is due to collateral roads, and . 
as motor nerves have none, motility is, in general, extinct without possibility ~ 
of return, by their division. 
Some time later nervous regeneration was definitely established by - 
numerous observations and experimental researches. 
How does it take place? 
When a nerve has been divided, the peripheric end loses its properties. 
In each interannular segment, at the same time that the nucleus lying - 
against the sheath of Schwann swells and proliferates, the myeline breaks it . 
on its external face, on a level with each incision of Lantermann, and is thus: . 
divided into balls... The cylindraxis, affected by the nuclear proliferation, is . 
in its turn indented and thousands of times cut alongside the degenera- 
ting fibres; soon it disappears, as well as the myeline, which is resorbed.. 
The sheath of Schwann is then filled with protoplasm and nuclei; later, 
these last elements atrophy, the protoplasm in its turn is resorbed and of = 
the nervous thread there remains but empty sheaths of Schwann, plicated, . 
lost in the middle of a fibro-fatty tissue. "This change is general and 
absolute—with exception for the recurrent fibres—and if regeneration 
takes place, the cylindraxis must be rebuilt entirely. 
Curious modifications occur in the central end, which do not extend 
beyond the first annular contraction. In this short portion, the nuclei 
proliferate, the myeline breaks up. There, a round or ovoid swelling 
(central bulb of the neuroma of regeneration) is formed, grayish-white in 
color, adherent to the surrounding tissues, encysted in a cicatricial mass... 
and united to the peripheric end by an intermediate tractus (cicatricial. 
segment) which serves as conductor to the regeneration. The cylindraxis,. 
instead of undergoing regressive changes, as in the peripheric end, be- 
come the seat of a special constituting activity; except those belonging - 
to recurrent fibres on the road to destruction, these cylindraxis granulate-. 
at the point of the first contraction, from which start myeline tubes-. 
which ramify in the neuroma of generation. A single cylinder may give 
twenty, thirty, forty of these tubes, which may be very irregularly arranged,.. 
entangled, running through a thick conjunctive mass. 
When the ends of the divided nerve are united or close to each other,,, 
