22 Mr . Home’s Lecture 
thickened cornea, and the vessels in its substance have poured 
out red blood. 
The cornea is not only capable of uniting by the first inten- 
tion, inflaming, and suppurating, but when the inflammation 
is carried to a great height, a portion of its substance is some- 
times removed by ulceration, and the ulcer so formed is filled 
up by coagulating lymph, which afterwards becomes cornea, 
acquiring the necessary property of transparency. This new 
formed part is weaker than the rest of the cornea, and com- 
monly projects beyond it, forming one species of staphyloma ; 
in the substance of the cornea, round the basis of the staphy- 
loma, I have frequently seen vessels carrying red blood. 
From the opinion of the cornea being devoid of life, the 
opacities which are found to take place on it have been consi- 
dered apart from common surgery, and entrusted to the care 
of men who are supposed to have made the diseases of the eye 
their particular study. 
According to this theory, the opacity was supposed to arise 
from a film of inanimate matter laid over the cornea, and upon 
that idea very acrid and irritating applications were employed 
with the view of scraping it off, or destroying it, as powdered 
glass, powdered sugar, &c. and such applications being of 
service, confirmed the opinion which gave rise to the practice. 
Having shown that the cornea is possessed of life, I shall 
now point out the parts of the body it resembles in structure, 
and to which it bears the greatest analogy, both in its healthy 
actions, and those arising from disease; and endeavour, by 
comparing them, to establish some general principle which 
will explain the beneficial effects of irritating applications in 
cases of inflammation and opacity of the cornea. 
