268 
ON PNEUMONIA. 
Over-exertion is a frequent cause of Pneumonia. It appears to 
have its influence by the congestion that takes place in the lungs, 
in consequence of the increased action of the heart, the right 
side acting as equal to two, whilst the left is equal only to one. 
An impure atmosphere, we are informed, produces its baneful 
effects by causing inflammation of a chronic kind, which ulti¬ 
mately terminates in tubercles and vomicae, and the disease thus 
engendered is more generally, I believe, the commencement of 
farcy and glanders, than of acute inflammation of the lungs. Mr. 
William Percivall, to whom we are all much indebted for his well- 
written lectures on the veterinary art, considers that Pneumonia 
is not produced by breathing a foul air; and he furnishes us with 
many important arguments and facts in support of this theory. 
As I am not disposed, gentlemen, to combat with such a formid¬ 
able opponent, I will, by your permission, read a passage from 
his lecture on the diseases of the lungs, which relates to this 
part of our subject; and shall then leave you to draw your own 
conclusion. He says, Vol. II, page 314, “ Can an atmosphere 
of a mean temperature, contaminated with the animal effluvia 
generated in the decomposition of the excretions, and the car¬ 
bonic acid gas cast off with the expired air, be considered of 
itself as an excitant of Pneumonia ? Now as heat is a pretty 
constant constituent of such an atmosphere, it appears, at first 
view, difficult to say whether it be to one or the other that we 
should ascribe the excitation of disease: from numerous facts 
and observations, however, collected by practitioners who have 
paid attention to this subject, with many of whom I have held 
converse, I feel inclined to believe that Pneumonia is rather the 
product of heat than of animal poison. There have been situa¬ 
tions occupied by great numbers of horses in which these poison¬ 
ous agents may be said to have been present without the co¬ 
operation of heat; and where, though the prevalence of other 
diseases sufficiently evinced their morbid influence, Pneumonia 
was hardly ever seen. In averring thus much, I allude more par¬ 
ticularly to what happened in the practice of the veterinary 
surgeons (of whom I myself was one) who did duty with the 
army in the Peninsula. Both in Portugal and Spain most 
of the stables, or places used as stables, were dirty and filthy 
in the extreme, being either without any pavement at all, or 
so badly paved that there were no sewers to drain off the 
urine. In these situations both horses and mules, of which 
the number was considerable during the march, contracted 
farcy , glanders , and mange; but very few of them inflam¬ 
mation of the lungs: and simply, I believe, for this reason, 
that the stables, though unwholesome from being so foul, were 
