344 .Mr. Home’s Account of an Orifice 
or in eyes that are blind, also of its being brighter in young 
people, and paler in old, it would appear, that it is only whe'n 
the eye is capable of performing its functions, that there is any 
stain communicated to the retina. 
EXPLANATION OF THE PLATE (Tab. XVII.) 
The drawings from which the figures are engraved were 
made from preparations of the eye lying in water, with a strong 
light shining upon the preparation. In making the drawings, 
the principal object was, procuring a distinct view of the parts 
surrounding the optic nerve; when this could be obtained, the 
situation of the eye itself was not attended to. 
Fig. 1 . A transverse section of the human eye, immediately 
before the ciliary processes. The retina is viewed through the 
posterior portion of the capsule of the crystalline lens. 
a. The termination of the optic nerve. 
b. The aperture in the retina, discovered by Professor 
Soemmering. 
Fig. 2. A longitudinal section of the left eye in the human 
subject, to show the relative situation of the aperture in the re- 
tina to the entrance of the optic nerve, and the mode in which 
it appears to project, when the vitreous humour is disturbed. 
a. The termination of the optic nerve. 
b. The aperture in the retina. 
Fig. 3. A transverse section of the eye of a large monkey, 
to show the aperture in the retina : its situation is the same as 
in the human eye. The zone has the appearance of a star with 
four rays. 
a. The entrance of the optic nerve. 
b. The aperture in the retina. 
