152 JOURNAL OF COMPARATIVE NEUROLOGY. 
pheral nerves of the dog, using the same technique as was em- 
ployed for the cross-section of the fibers. 
Fig. 2 shows the general arrangement of the nerve fibers, 
as well as the manner of distribution of the neurokeratin. In 
this figure, the well known cone-shaped or funnel-shaped struc- 
tures are shown clearly. The cone, as is known already, is 
formed by the network of the neurokeratin; the basal or wide 
end attaches to the outer layer of the neurokeratin sheath, 
while the narrow tip is attached to the neurokeratin sheath 
which directly surrounds the axis cylinder. In many cases, in- 
stead of the single cone there is the appearance of two cones 
united by their apices and at their bases attached to the outer 
margin of the sheath, as is shown in Fig. 2. The shape, size, 
direction, as well as number in each internode of the nerve 
fiber, is not constant. In some fibers the distance between the 
two narrow tips of the cones is quite regular, and the median 
longitudinal section of such fiber shows it to be divided into 
equal segments by means of the neurokeratin funnels or cones. 
(Fig. 2, 7). Both the outer and inner layers of neurokeratin 
network are continuous throughout the entire length of the 
nerve fiber, as they are not interrupted at the nodes of Ran- 
VIER (Fig. 2, a,g.) The structures of the cones and their rela- 
tion to the two sheathing layers are shown in Fig. 4. I have 
mentioned already that double rings of the neurokeratin are no- 
ticed in examining the cross-sections of the fibers, and further 
gave the hint that the dots forming the rings are connected by 
means of delicate filaments of the same substance, and these 
connecting filaments are in turn continuous by means of the 
side-branches. Such a complicated arrangement may be under- 
stood by examining the structures drawn in Fig. 2 and Fig. 4. 
Since the two sheathing layers of the neurokeratin are con- 
nected either by radial filaments from the inner sheath toward 
the outer layer or by the branches which are sent off from the 
inner surface of the cones toward the inner neurokeratin sheath, 
there is thus formed a complicated arrangement of the neuro- 
keratin in the cross-sections of the fibers. In most cases, the 
outermost layer of the neurokeratin has fine meshes, as is 
