ON THE RECENT EPIZOOTIC AMONG HORSES. 703 
conjunction with decayed vegetable matter and moisture. On this 
principle we may, in some measure, account for its not being more 
universal; for it makes its attack only here and there. If the at¬ 
mosphere was universally empoisoned, its effects would not be so 
locally confined, and more animals would become infected; whereas 
it runs its course with two or three farm horses or hacks on one 
farm or in one stable, breaking out again in contrary sites, a mile 
or two apart; the intervening farms and stables remaining free. 
This shews that the malaria capable of causing it is generated, 
not universally, but from definite situations, under certain condi¬ 
tions, and fluctuating in the atmosphere in detached parts or portions, 
and there being no visible indication of its presence. 
To return to moisture: it is regarded, when stagnant on dead 
vegetables, as the frequent source of malaria, forming gases unfit 
for respiration, and of an heterogeneous kind, capable of producing 
diseases in the animal frame: and, no doubt, the influenza in 
horses—could but the eye discern this miasmatic vapour—would 
appear like cumulo-stratus clouds, wafted over hill and dale. 
The effect of drought on the surface or superficial herbage of the 
earth is a deprivation or suspension of their natural juices, and 
inert, probably, in this state: a warm temperature with humecta- 
tion follows; animal bodies are brought into existence, and me¬ 
phitic vapours arise and empoison the air. This is a fruitful field 
for research and inquiry, and well may we say, let us 
“ Search undismayed 
Nature’s dark profound, that works in secret.” 
Vitiated emanations, whether arising from deca 3 md animal or 
vegetable matter, produce disease in conformity with the resulting 
products of their decomposition. Measles, scarlatina, variola, &c., 
according to pathologists, have their own inherent agency or prin¬ 
ciple. Some, again, assert malaria to be the produce of diseased 
secretions arising from living vegetable matter in a state of disease. 
This may be a too limited speculation. It would be requisite to 
have a large area or space of diseased vegetable substances in 
order to maintain an empoisoned air; whereas moisture, on a soil 
not possessing an absorbent (quality, would keep up, in conjunction 
with vegetable matter under the laws of inorganic or organic de¬ 
cay, an undeterminable evolution of noxious vapours. 
An animal coming into contact with the aerial poison which pro¬ 
duces the influenza, whether depasturing or in the stable, probably 
imbibes a portion, or, in other words, one of the constituents of the 
vital fluid has an affinity for it. The result will be a new com¬ 
pound or an uncoirjbined agent—both injurious to animal life— 
going the round of the circulation, and, like most general or local 
