exist in the vital fluid in unusually large quantities, or if the
respiratory capacity be inadequate, the natural internal crematory
operations are a partial failure. But nature will not tolerate the
presence of such impurities in the vital fluid; if they cannot be
eliminated by natural means they must by unnatural means; therefore
such material is very frequently deposited in various parts of the
body, the point of deposit being often determined by some local
disturbance or irritation.

For instance, if a person whose blood is in fairly good condition
takes a cold that settles on his lungs, he either recovers of it
spontaneously or is readily cured by means of some cough mixture; but
if his blood be loaded with tubercular matter, the latter is extremely
liable to be deposited in his lungs; the cough that was excited in the
first place by a simple cold becomes worse and persistent, in a few
months his lungs show signs of disorganization, and he has consumption
of the acute or chronic type, as the case may be.

On the other hand, if the impure matter by which the blood is loaded
be of the kind that causes the pulmonary solidifications of pneumonia,
the latter disease is very likely to be developed if a cold on the
lungs be caught.

The liability of any individual to attacks of acute pneumonia is
therefore determined very largely by the presence or absence in his
blood of the matter already alluded to. If his blood be free from it,
no cold, however severe, is competent to originate the disease.

There can be no question but that good living and sedentary habits
have a strong tendency to befoul the blood; the former renders