Injuries of nerves and their consequences - Reflex Sympathetic ...

ANATOMY OF NERVES. 17
The cylinder axis is a flexible rod of azotized matter
which fills
the tube formed by the white medullary tissue
When the nerve is torn, the axis cylinder can
around it.
sometimes be seen projecting, button-like, from the torn
end of the tubular membrane and medullary substance.
Numerous conjectures have been formed as to the ultimate
structure of this portion of the nerve tubule some
;
having described it as composed of minute longitudinal
fibres, while others regard it as made up of laminte placed
one upon another. Every physiological reason would teach
us, however, to accept with Schultze, in Strieker's "Handbuch,"
the belief that the ultimate anatomical neural
element is what he terms the primitive fibril,
— of which a
number, great or small, is needed to make an axis cylinder,—
so that the primitive fibril is the essential nerve
element around which, or around groups of which, may
be the medullary sheath and the sheath of Schwann,—
although of the modifications in physiological function
which these impress upon it we know absolutely nothing.
Fromman, and more recently Grandry,* by exposing
the nerves to a peculiar treatment with nitrate of silver,
reached the conclusion that the cylinder axis is
composed
of disks superimposed and isolated by a substance differing
from them in composition. I have verified these
observations on the sciatic nerve of the rabbit with preparations
made by Dr. Keen, and obtained the same result,
so that it seems difficult, considering the regularity of the
structure thus brought out, to reach any other conclusion
than that the axis is
probably less simple in construction
than has been believed. If we admit with Schultzef and
Strieker that this substance also possesses longitudinal
strise, the likeness to the anatomical disposition of the
* Journ. de I'Anat. et Phys., 1869, p. 289.
f Disc. Acad. Bonn, Aug. 1868.