Monthly Mlcroscoplcan 
Journal, Nov. 1, 1SC9. J 
Histology of the Eye. 
249 
Fig. 12. 
Spinning an excessively fine web around the cells and fibres, it 
maintains them all in position, and it supports the blood-vessels 
when these are present. To sum up, the connective tissue occurs 
in three forms — membranous, as the membrana limitans externa 
and interna ; fibrous, as Miiller's radial fibres ; and as an exces- 
sively finely-fibrillated interstitial web. 
It is a remarkable circumstance that the retina in the greatest 
number of vertebrate animals does not contain any hlood-vessels. 
A retinal vascular system is confined, I believe, to mammalia ; and 
amongst these there are great differences in the distribution of the 
vessels. In man, the whole extent of the retina, from the optic 
nerve entrance to the ora serrata, is vascularized ; and the same 
obtains, I believe, in the ox, sheep, deer, and antelope ; while in the 
hare the vessels are restricted to the area of the opaque nerve- 
fibres ; and in the horse they form a narrow zone around the optic 
nerve entrance. 
In the human retina no capillaries penetrate farther outwards 
than the intergranule layer or the inner surface of the outer granule 
layer. In consequence of 
this arrangement, the rods 
and cones are nearer to 
the chorio-capillaris than to 
the retinal capillaries. This 
alone would make it pro- 
bable that they derive their 
nourishment from the capil- 
laries ; and morbid anatomy 
abundantly confirms this, for 
it is an established fact that 
atrophy of the chorio-capil- 
laris, entailing atrophy of 
the hexagonal pigment epi- 
thelium, is also followed by 
atrophy of the rods and 
cones. 
In the common hedge- 
hog I have observed a pecu- 
liar disposition of the ves- 
sels, which is intermediate 
between the typical distri- 
bution in man and most 
other mammals I have ex- 
amined, and that which ob- 
taiiis in the lower vertebrates ; viz. the larger vessels, arteries, and 
veins, channel the capsula hyaloidea, while capillaries only pierce 
the retina. 
Vertical Sectioa of Retina, to illustrate the Distribution 
of the Vessels. 
