such as maize,
wheat, and buckwheat, are to be carefully avoided. It has been widely
charged that beans, peas, vetches, and other Leguminosae are dangerous,
but a fuller inquiry contradicts the statement. If these feeds are well
grown, they invigorate and fortify the system, while, like any other
fodder, if grown rank; aqueous, and deficient in assimilable principles,
they tend to lower the health and open the way for the disease.

The period of dentition and training is a fertile exciting cause, for
though the malady may appear at any time from birth to old age, yet the
great majority of victims are from 2 to 6 years old, and if a horse
escapes the affection till after 6 there is a reasonable hope that he
will continue to resist it. The irritation about the head during the
eruption of the teeth, and while fretting in the unwonted bridle and
collar, the stimulating grain diet and the close air of the stable all
combine to rouse the latent tendency to disease in the eye, while direct
injuries by bridle, whip, or hay seeds are not without their influence.
In the same way local irritants, like dust, severe rain and snow storms,
smoke, and acrid vapors are contributing causes.

It is evident, however, that no one of these is sufficient of itself to
produce the disease, and it has been alleged that the true cause is a
microbe, or the irritant products of a microbe, which is harbored in the
marshy soil. The prevalence of the disease on the same damp soils which
produce ague in man and anthrax in cattle has been quoted in support of
this doctrine, as also the fact that, other things being equal, the
malady is always more prevalent in basins surrounded by hills where the
air is still and such products are concentrated, and that a forest or
simple belt of trees will, as in ague, at times limit the area of its
prevalence. Another argument for the same view is found in the fact that
on certain farms irrigated by town sewage this malady has become
extremely prevalent, the sewage being assumed to form a suitable nidus
for the growth of the germ. But on these sewage farms a fresh crop may
be cut every fortnight, and the product is precisely that aqueous
material which contributes to a lymphatic structure and a low tone of
health. The presence of a definite germ in the system has not yet been
proved, and in the present state of our knowledge we are only warranted
in charging the disease to the deleterious emanations from the marshy