OPHTHALMIA. 
261 
shed upon the nature of the disease and the suggestions they 
furnish for its prevention. Hereditary influence is one of the 
causes which some of the profession claim it arises from, and 
no doubt it can be well sustained, for the records show that in 
those countries where there is no restriction as to what can be 
used for breeding, they have a larger percentage of the disease, 
but there is some doubt in my mind as to whether in this case 
it is the disease that is transmitted or only the predisposition. 
If this is answered “yes,” how then is it that the disease so 
much confines itself to horses of certain ages and situations ? 
If “ no ” is the answer, then ask yourself why the production of 
the disease under certain conditions and states of excitement 
can be most satisfactorily accounted for. I am still firmly of 
the opinion that it is predisponent only and not excitant. 
We now come to the question : whether this disease is con¬ 
stitutional or local ; or, in other words, is it due to some micro¬ 
organism in the blood or is the predisposition inherent in the 
formation or excitability of the eye ? These are most interest¬ 
ing questions of which various facts and observations, current 
among us, may be brought forward by investigation. But it 
matters not whether this is called hereditary or due to an origi¬ 
nal predisposition, it amounts to one and the same thing, and I 
will venture to say that this is by far the most frequent cause of 
the disease ; but while I make this assertion, I stand ready to 
admit that it also arises from a variety of other causes, quite 
adventitious and unconnected with this source. Among these 
may be mentioned indigestion, miasma, neuritis, dentition, de¬ 
bility from overwork, depletion from blood-letting, high feed¬ 
ing, too much confinement and sudden exposure to light. It is 
also a very noticeable fact that those horses not accustomed to 
domestication are, generally speaking, free from it and it is 
noticed to be more prevalent in poorly ventilated stables, the 
same as other constitutional diseases. 
To what then is ophthalmia to be attributed? The advo¬ 
cate of hereditary influence answers : to the circumstance of the 
parent having had it. While others will say, u no,” but to 
