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G. ED. LEECH. 
mation, and in general require some considerable time for its 
completion. The first attack, mild in its nature and not of long 
duration, may leave the eye altered only in such respects as in 
the course of a long intermission may be rectified. Commonly 
after the second attack and occasionally after the first there will 
still remain more or less haziness of the cornea, through which 
we perceive the iris lustreless and murky in its aspect, the 
pupil contracted and without any of its natural bright blue to 
be seen. The corpora nigra also appears more pendulous than 
usual, wanting their jetty blackness and on occasions exhibit¬ 
ing light specks or opacity, and every subsequent attack will 
add to these structural changes. 
Morbid Anatomy.— D’Arbovals, the eminent French veteri¬ 
narian, says that observation shows that an absence of any dis¬ 
tinct chambers containing aqueous humor, nothing, in fact, but 
a single cavity remaining ; sometimes the iris appears lacerated, 
detached from the lens, reduced to a very small volume, its cap¬ 
sule only remaining perhaps thickened and opaque ; at other 
times the lens is of its natural size, its capsule being opaque, 
with some white spots in its substance and concretions upon its 
inner surface. The posterior portion of the crystalline lens is 
thickened and indurated, almost as if it had been boiled, and it 
reflects a bottle-<?reen color. The fibres of the iris surrounding 
the lens on some occasions become osseous and in the place ot 
the vitreous humor, resulting from its decomposition, we find a 
viscous orange-colored fluid heavier than water. Instead of the 
retina there is a fibrous membrane behind the crystalline, the 
optic nerve is flabby and softened. 
Geldings are more liable to suffer from this disease than 
mares, and by some writers it is supposed that there is some 
connection between dentism and ophthalmia. The eye most 
subject to this disease is the very small dark looking one, which 
does not disclose any appearance of the white, wall or watch 
eyes seeming to be exempt. 
The causes of periodic ophthalmia demand the greatest 
attention from us, both upon account of the light which they 
