244 ON THE PRESENT EPIZOOTIC AMONG HORSES. 
would say, let them give the position some reflection before they 
entirely condemn it. There can be little doubt that the exist- 
ence of almost all epidemical and epizootic diseases is attri- 
butable to a peculiar state of the common medium by which we 
are surrounded. There is a certain peculiarity in the atmo- 
sphere of which we cannot take cognizance, excepting through 
the medium of the marked effects which it produces on the animal 
economy. The question then arises — How does it produce those 
effects] Is it by coming merely in actual contact with the par- 
ticular part affected ] Or is it through the medium of respiration 
that the vital stream becomes impregnated, and thus disseminates 
the morbid principle throughout the entire system, to exert its in- 
fluence on those parts on which it seems to have its specific action ? 
Surely such a theory is by no means untenable, especially when 
we take into consideration that there are many tangible forms 
of poison, which, no matter however introduced into the sys- 
tem, invariably produce the same specific effect when destruc- 
tive to life: thus arsenic, when applied with fatal effect even to 
the external surface alone, will cause inflammation and ulceration 
of the stomach ; and tartar emetic, when injected into the vascu- 
lar system, produces exactly the same effect as when taken into 
the stomach — violent vomition. There are, however, many patho- 
logical facts, which completely set aside the probability of the 
parts affected with epidemic disease having become so merely 
by their contact with the miasma floating in the atmosphere. 
While on the continent, I had an opportunity of investigating a 
disease of the spleen which raged as an epizootic among the 
bovine cattle throughout the whole of the south of Europe for a 
considerable time. Sudden in its attack, rapid in its course, 
and generally fatal in its termination, it was the means of causing 
an incredible scarcity of ox meat for a long period throughout 
every district that it visited. Here it must be admitted the 
theory of actual contact falls to the ground. These facts, and a 
number of phenomena which present themselves consequent on 
the mode of treatment that has been usually adopted, induce me 
to come to the conclusion that the seat of diseased action in the 
present equine epizootic rests in a derangement of function in 
the organic system of nerves, more particularly that portion of 
them which influences the action of the mucous surfaces. Whe- 
ther this derangement of the organic system be primary, as the 
seat of the disease, or secondary, as the effects of sympathetic 
action, there are no means of exactly determining; the elucida- 
tion of disease being a matter that admits of bat little theorising. 
Yet it must be borne in mind, that, whether primary or secondary, 
it is frequently so intense, as, by a species of reflex action on 
