PASH 2) 
All figures are from Necturus. Figures 7 to 11 are magnified 1,450 
diameters; Figures 12 to 16 are magnified 1,000 diameters. 
Fic. 7—A large rod, slightly separated from its nucleus, and a double 
cone, the near cone in focus. In the latter, superficial fibrils are visible 
at the base of the outer segment, passing over the ellipsoid, paraboloid, 
and nucleus, and converging proximal to the nucleus in the cone foot. 
The fibrils of the rod in this particular preparation are more diffuse in 
the region of the foot than those in the foot of the neighboring cone. The 
material was fixed in corrosive-acetic mixture and stained in Mallory’s 
triple stain (Mallory, : 00). 
Fic. 8.—A single rod showing the relation of the stained fibrils to the 
nucleus and the rod-foot. The fibrils of adjacent elements are distinct 
until they diverge at the outer reticular layer of the retina. The nucleus 
of the rod in the center has shrunken away from its sheath, at its 
proximal end. The parabaloid in optical section gives the appearance of a 
coarse blue reticulum. The fixation and stain were the same as in Fig. 7. 
Fic. 9.—A cross section of the outer segment of a rod. The fibrils are 
distinct when seen in section. As a rule, vacuoles alternate with the fibrils. 
Fics. 10-11.—A cone and a rod, fresh, in normal fluids of the eye, and 
drawn in situ a few minutes after the removal of the retina from the living 
animal. Only a small portion of the nucleus of the rod is shown. The 
changes which so rapidly set in upon the death of the animal have already 
begun here. The outer segment of the cone, most unstable of all, shows 
evidence of disintegration; granulation has commenced in the ellipsoids 
and is more pronounced in the nuclei. The parabaloid remains compara- 
tively clear for some time. The latter is more refractive than the sheath, 
but less refractive than the ellipsoid. In the cone (Fig. 10) the paraboloid 
is a great deal more flattened than usual. A common relation of paraboloid 
and nucleus for fresh cones is shown in PI. 3, Fig. 20. 
Fics. 12 to 16.—Outer segments of fresh rods in fluid from the eye, 
showing progressive disintegration. Figures 12 to 14 were drawn within 
half an hour after the rods were removed from the eye. In Figure 12 the 
upper surface is in focus and only one diagonal is visible, while in Figure 
13, where the lower surface is in focus, several of the diagonals (fibrils) 
are visible. The difference in the number of lines visible is apparently due 
to the optical effect of the cylinder. Figure 14 represents the appearance 
of a rod at the very lowest focus at which lines are visible. The more 
highly refracting fibrils are dark in low focus, while the less refractive 
intermediate substance appears light. 
Fic. 17.—An outer segment of a fresh rod seen in optical section. 
This view was obtained by laying a portion of a retina flat on a slide and 
focusing upon the rods in situ. In a retina thus examined the crenated 
edge of rod outer segments is very apparent, and in many instances where 
disintegration has commenced, radial fissures of variable length are to be 
seen extending inward from the sinuses. ‘The rods that are still intact 
show at first sight a homogeneous center with a crenated sheath; by close 
inspection this sheath proves to be made up of separate bodies (the fibrils 
in section). These are brought out more distinctly where the rods are 
illuminated by a direct light from the side. 
