DISEASES OF THE RESPIUATOHY ORGANS. 
333 
as remarkable as the previous immunity, is perceived. In 
no instance is this more-marked than during the prevalence 
of epidemic catarrh, which attacks subjects in the most 
capricious manner, often leaving those seemingly most pre¬ 
disposed, and certainly most under the influence ^of atmo¬ 
spheric causes, to affect others whose condition should have 
afforded a protection, and on wliose behalf every possible 
precaution had been taken. Even in the case of common 
cold, which often assumes an enzootic or epizootic character, 
so much as to give rise to a very general belief of its infectious 
nature, it has often seemed to us to occur when no reasonable 
charge could be alleged against the atmosphere, which, so far 
from experiencing extreme change, has, on the contrary, pre¬ 
served a remarkable uniformity, giving no colour to the plea 
of transition from hot to cold, or cold to hot, upsetting our 
nicely constructed arguments, and settling the controversy 
as to relative influences of each by proving to demonstration 
that neither was coneerned, and forcing one to the somewhat 
unsatisfactory conclusion that some poison, of a nature so 
subtle as to elude detection, must be present in the air we 
breathe. 
It accords, we believe, with general experience to state, 
that among respiratory diseases we meet with very little of 
an active charaeter. Fifteen years ago, and even later, we 
can recollect cases of inflammation of the lungs, attended with 
a full, bounding pulse of 70 or 80, maintaining its force after 
three or four bleedings in the course of two or three davs ; 
cases which would support the effects of depletive treatment 
for a fortnight, and leave the animal not more prostrated 
than he now is left after a few days^ illness, with a system of 
treatment whieh permits depletion to be only very cau¬ 
tiously and temperately employed. What has become of 
those full venesections, those exhausting rowels, those 
fabulous doses of digitalis, or hellebore, and all the medicinal 
host whose aid we were wont to invoke in our efforts to kill 
disease ? Gone! all of them, to make up a harrowing 
record in our earlier case-books, whose perusal in the present 
day makes us almost doubt the evidence of our own hand¬ 
writing. 
According to established usage, it is necessary to attempt 
some sort of classification of the maladies which are located 
in different parts of the respiratory system, in order to escape 
the confusion that must otherwise occur where diseases pass 
into eaeh other almost imperceptibly. In a great number of 
cases we find the mucous membrane particularly affected, 
from the nostrils to the larynx, and ultimately to the 
