the disease had previously prevailed, practically banished the
affection. Whatever contributes to strength and vigor is protective;
whatever contributes to weakness and poor health is provocative of the
disease in the predisposed subject.

_Symptoms._--The symptoms vary according to the severity of the attack.
In some cases there is marked fever, and in some slighter cases it may
be almost altogether wanting, but there is always a lack of vigor and
energy, bespeaking general disorder. The local symptoms are in the main
those of internal ophthalmia, in many cases with an increased hardness
of the eyeball from effusion into its cavity. The contracted pupil does
not expand much in darkness, nor even under the action of belladonna.
Opacity advances from the margin, over a part or whole of the cornea,
but so long as it is transparent there may be seen the turbid, aqueous
humor with or without flocculi, the dingy iris robbed of its clear,
black aspect, the slightly clouded lens, and a greenish-yellow
reflection from the depth of the eye. From the fifth to the seventh day
the flocculi precipitate in the lower part of the chamber, exposing more
clearly the iris and lens, and absorption commences, so that the eye may
be cleared up in ten or fifteen days.

The characteristic of the disease is, however, its recurrence again and
again in the same eye until blindness results. The attacks may follow
one another after intervals of a month, more or less, but they show no
relation to any particular phase of the moon, as might be inferred from
the familiar name, but are determined rather by the weather, the health,
the feed, or by some periodicity of the system. From five to seven
attacks usually result in blindness, and then the second eye is liable
to be attacked until it also is ruined.

In the intervals between the attacks some remaining symptoms betray the
condition, and they become more marked after each successive access of
disease. Even after the first attack there is a bluish ring around the
margin of the transparent cornea. The eye seems smaller than the other,
at first because it is retracted in its socket, and often after several
attacks because of actual shrinkage (atrophy). The upper eyelid, in
place of presenting a uniform, continuous arch, has, about one-third
from its inner angle, an abrupt bend, caused by the contraction of the
levator muscle. The front of the iris has exchanged some of its dark,
clear brilliancy for