EYEBALL, 67 
7—External nuclear layer. 
8—Membrana limitans externa. 
9—Layer of rods and cones. 
10—Pigment layer. 
Describe the limiting membranes. 
They are perforated by numerous openings and are very delicate and 
homogeneous. They belong to the connective tissue of the retina. 
From what is the layer of nerve fibres derived: ? 
It is formed by the expansion of the optic nerve after it has passed 
through the coats of the eye. This layer is thicker in the posterior 
than in the anterior portion of the eye. 
Describe the layer of nerve cells. 
It is composed of large nerve cells resembling Purkinje’s cells in the 
cerebellum. On one side they have an axis-cylinder, continuous with 
a nerve fibre, and on the other side branching processes which are lost 
in the other layers. 
Of what is the inner molecule composed ? 
Of cells resembling the neuroglia of the gray matter of the brain. 
What is the structure of the inner nuclear layer ? 
It is composed of bipolar cells having large nuclei. 
What is the structure of the outer molecular layer? 
It is thin, and composed of branching cells, the processes of which 
interlace. 
What is the structure of the outer nuclear layer ? 
It is made up of a delicate network of nerve fibrils mixed with con- 
nective tissue. Its nuclei and cells are intimately connected with the 
layer of rods and cones. 
Describe the layer of rods and cones. 
The rods are the longer elements and are pointed where they join 
the nerve fibres of the external nuclear layer. The cones are shorter; 
connecting with nerve elements internally, they terminate externally in 
a pointed or rounded extremity. . 
Describe the cells of the pigment layer. 
Seen on the surface they appear as large hexagonal-shaped cells, 
side by side, forming a layer over the ends of the rods of the preceding 
layer. 
