Monthly Mlcroscoplrall 
Journal, Nov. 1, 1869. J 
Histology of the Eye. 
the bright orange and ruby beads of diurnal birds ; and from this 
he conjectures that the cones may be concerned in perception of 
colour. 
The outer granules, to which I must now pass on, are not 
minute, angular, solid particles, as their name implies, but cells or 
nuclei of very appreciable dimensions. Their numbers are directly 
proportionate to those of the rods and cones : and it is very pro- 
bable — I may say certain — that each outer granule is associated with 
a rod or cone, and this in one of two ways. When the rod or 
cone-appendage is large enough to hold it, the outer granule lies 
inside the appendage in the plane of the membrana limitans interna, 
or at its inner surface ; but, when the appendage is too slender to 
contain the granule, it is joined to the granule by a communicating 
fibre, the length of which is determined by the distance between 
the inner end of the appendage and the granule. In either case, 
the appendage is prolonged inwards in the form of a band or fibre 
beyond the "outer granule" towards the next stratum. This 
fibre I call the primitive bacillary fibre, or the primitive rod or 
cone-fibre, when I wish to distinguish it more particularly. 
The intergranule layer, which, as its name conveys, lies between 
the outer and the inner granules, is a fibrous stratum. Some of 
its component fibres are nervous, passing between the outer and 
inner granules, and others are connective tissue. Of the latter set 
of fibres, those which traverse the layer vertically belong to the 
system of connective radial fibres, known by the name of their 
discoverer, H. Miiller. The others, which extend parallel to the 
direction of the layer, constitute its proper substratum ; and 
amongst these lie imbedded small nuclei, and in some of the lower 
animals, e. g. chelonians and fishes, large branched corpuscles of 
very considerable dim.ensions. 
The inner granules, like the outer ones, are also cells or nuclei. 
According to their sizes, which vary much, they fall into two sets 
— smaller granules, everywhere numerous ; and larger ones, most 
abundant near the inner surface of the layer, which I cannot dis- 
tinguish from ganglion-cells. On the one side, the inner granules 
receive the fibres sent inwards towards them through the inter- 
granular layer from the outer granules ; and, on the other side, 
they send fibres inwards into the granular layer towards the 
ganglion-cells. 
The grartular layer, as Schultze correctly pointed out, is re- 
solved, by a sufiiciently high magnifying power, into a very finely 
fibrillated spongy web, which manifestly hangs together with, and 
is in great part a derivative of, the connective radial fibres entering 
it. The only nervous elements occurring in it are the internuncial 
fibres which traverse it, and the outermost ganglion-cells bedded in 
its inner surface. The term granular, which simply expresses its 
