1901) MICROSCOPICAL JOURNAL. ~ 69 
ullated fibres which are contained in all sensory-motor 
nerves, and to the fact that they appear to degenerate 
specially early and completely in peripheral neuritis. 
These fine fibers are of extremely small size ; they havea 
distinct, although comparatively slender, myelin sheath, 
and they generally occur in small groups throughout each 
funiculus. These fibers have often been mistaken for 
non-medullated nerve fibers when the myelin sheaths have 
not taken on the staining reagent sufficently deeply. In 
a paper published in the Journal of Anatomy and Physi- 
ology, 1 ventured to assert that these fibers were mainly 
vaso-motor in function, an opinion held also by Gaskell, 
and were more intimately associated with the changes in 
the blood-vessels, and the exudations which occur in per- 
ipheral neuritis. These fibers are especially well sup- 
ported by connective tissue strands, and when they de- 
generate they are replaced by fairly dense fibrous tissue 
which marks their former site. This I can show you from 
sections taken from the central end of a rabbit’s sciatic 
nerve, some six weeks after division or ligature, special 
care having been taken to prevent reunion occurring. 
Just above the section or ligature, the sites of these 
fine fibres are marked by small dense areas of connective 
tissue. This is due, I believe, to the rapid degeneration 
of these nerve fibers when their function is interfered with, 
the vessels which they supply being in the peripheral part 
of the limb. A little higher up these small strands of 
fibrous tissue still contain a few healthy minute nerve 
fibers, and the number increases as the nerve is followed 
upwards to the cord. 
The association between these fibers and the vessels can 
be traced in the following way :—The fibrous tissue re- 
placing the fine fibers contracts, and where most of the 
fine fibers have lost their function—near the divided end 
of the nerve— any fine fibers in the immediate neighbor- 
hood, whose function is still intact, cannot escape pres- 
