504 S. WALTER RANSON 
degeneration in the first few millimeters of the stump. All 
measurements of this sort, referred to in this paper, were made 
on longitudinal sections with the aid of the microscope and 
mechanical stage. ’ 
At a distance of 5 mm. from the cut surface eight days after 
the operation, the axons of the medullated fibers are broken 
up into small irregular clumps of dark brown granules (fig. 3, a). 
The myelin sheaths are divided into elliptical segments, separated 
and surrounded by the now abundant protoplasm of the neu- 
rilemma cells, and containing the granular remains of the axons. 
In the preparations of this stage the nuclei are not differen- 
tiated, although it is known from the observations of others 
that at this time the nuclei of the neurilemma are rapidly in- 
creasing in numbers. There are a few medullated fibers whose 
axons are not fragmented, but are stained very intensely, have 
a fairly uniform contour and an intact myelin sheath. Cajal 
(08) has called attention to these resistant fibers. Since there 
are all gradations between the most susceptible and the most 
resistant, there seems to be involved not a distinction in the 
kind of fiber, but in the functional state, nutritive condition, 
and vitality of the fiber at the moment of the lesion. 
Fourteen days after the operation there are no longer any 
unfrzgmented medullated fibers, although some are in the early 
stages of degeneration. In most of the fibers the protoplasm 
has increased in quantity and the myelin is divided into drop- 
lets, while the remains of the axons are less in evidence. Nine- 
teen days after the operation the protoplasmic bands of Biingner 
have made their appearance (fig. 4). The small quantity of 
protoplasm surrounding the nuclei in the normal fiber has in- 
creased and surrounded the fragments of myelin. And as the 
remains of the axon and myelin have been absorbed, this proto- 
plasm has come to fill the old neurilemma sheath. In the mean- 
time the nuclei have increased in number. Asa result, we have 
a continuous band of protoplasm containing many nuclei (fig. 
4, a), and occasional droplets of myelin (b). Scattered through 
the remains of the myelin are fine, darkly staining granules 
representing the remains of the axon. The protoplasm some- 
