PLATE IV. 
Diagrammatic representations of the two kinds of tissue of which the retina 
of mammals, and especially that of man, is composed. xX about 500 
diam. 
Fig. 
1.—The connective-tissue framework of the retina. 
A, A. Membrana limitans externa. 
e, e. Radial trabecular fibres, with their nuclei ée’, é’. 
1, 7. M. limitans interna. 
Coarser and finer membranous and fibrous bands connect the 
radial fibres together, especially in meridional lines, so that the 
retina may be split into foliaceous sections more readily in a meri- 
dional direction than in any other. The closed fibrous plexuses are 
those corresponding to the intergranular layer d and the molecular 
layer g. 
2.—The nervous elements of the retina, commencing at the periphery with 
the rods 4 and the cones c, whose outer segments, however, do not 
appear to be continuous with the inner, but simply in a relation of 
contiguity. To these succeed the elements of the outer granule- 
layer, consisting of the rod- and cone-filaments; the latter furnished 
with nucleated enlargements J’ and c’, corresponding with the granules. 
In the intergranular layer d may be noticed an inextricable plexus 
of extremely delicate nervous filaments, which are prolonged on the 
inner aspect into the radial nerve-fibres of the inner granule-layer, 
which are again furnished with nucleated enlargements, with respect 
to which it has not yet been determined whether they do not (at any 
rate, in mammals and man) contribute in one direction or another to 
the multiplication of the fibres. The straight radial direction of the 
nerve-fibres is next interrupted by a plexus of extremely delicate 
fibrillee, which, together with that formed by the spongeiform con- 
nective tissue, constitute the molecular layer of the retina, which may 
be regarded as resembling the grey substance of the brain, and into 
which enter, from the inner aspect, the extremely fine ramifications 
of the processes of the ganglion-cells 4, 4, which, again, are in con- 
nection with the fibres of the optic-nerve-layer 7,7. But, here, the 
possibility must be regarded, that some of the innumerable and 
excessively delicate fibrillee of the optic nerve, which exist together 
with the coarser ones, in the optic-nerve layer of the retina, may not 
i enter the molecular layer, without the intervention of ganglion- 
cells. 
