292 DISEASES OF THE HORSE. 
with wet lands, are universally charged with causing the disease. 
These act on the animal body to produce a lymphatic constitution 
with an excess of connective tissue, bones, and muscles of coarse, open 
texture, thick skins, and gummy legs covered with a profusion of 
long hair. Hence the heavy horses of Belgium and southwestern 
France have suffered severely from the affection, while high, dry 
Jands adjacent, like Catalonia, in Spain, and Dauphiny, Provence, 
and Languedoc, in France, have in the main escaped. 
The rank, aqueous fodders grown on such soils are other causes, but 
these again are calculated to undermine the character of the nervous 
and sanguineous temperament and to superinduce the lymphatic. 
Other feeds act by leading to constipation and other disorders of the 
digestive organs, thus impairing the general health. Hence in any 
animal predisposed to this disease, heating, starchy feeds, such as 
maize, wheat, and buckwheat, are to be carefully avoided. It has 
been widely charged that beans, peas, vetches, and other Leguminose 
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 fond 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 sur- 
rounded by hills where the air is still and such products are concen- 
trated, 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 
game 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. 
