332 
ON SOME OF THE DISEASES OF THE EESPI- 
llATORY ORGANS OF THE HORSE AND 
OTHER ANIMALS. 
By Professor Brown^ M.R.C.V.S. 
(Continuedfromp. 203.) 
The prevalence of diseases of the breathing organs is a 
fact not difficult of explanation, when we consider the 
delicacy of the structures implicated, and the influence 
which the various atmospheric changes must necessarily 
exert upon them. 
Theoretically, the function of respiration is of vital im¬ 
portance ; any interruption to the process, or serious dete¬ 
rioration of the medium inhaled, should be followed or 
attended by general systemic disturbance. Not only is the 
blood restored, and rendered fit for the offices of nutrition 
by the absorption of oxygen, but numerous effete products 
are at the same time, and by the medium of the same 
physical process, eliminated; indirectly, therefore, the 
removal of the refuse and the supply of new material in the 
animal economy together depend upon the perfect per¬ 
formance of respiration. 
Notwithstanding the absolute truth of these statements, 
we are constrained to admit that derangement of the function, 
and deterioration of the medium inhaled do coexist without 
any very decided or palpable interference with nutrition. 
We do not intend to promulgate the doctrine that impure 
air may be breathed habitually with impunity, nor that 
organic disease of the lungs is compatible with fine health; 
but we cannot shut our eyes to the facts of everyday 
experience, showing how very disproportionately small an 
amount of injury does result under circumstances the very 
suspicion of whose existence would have justified the 
gravest apprehensions. 
AYhat we have often alluded to as the restorative power of 
the organism, the faculty which seems to oppose a passive 
but effective resistance to the effects of the various disturbinsr 
influences, may be adduced in the place of a better argument 
to explain what must have occurred to every observer as a 
problem not easy of solution. 
The resistant power of the system varies, however, very 
considerably,and,under certain circumstances, a susceptibility, 
