already deposited in the lungs in sufficient quantity to give rise to
the physical signs by which their presence is proved, this carefully
compiled table shows that the diminution of the vital capacity already
amounts to one-third of that considered by Dr. Hutchinson to be
necessary to the maintenance of health.

During the pre-tubercular stage the breathing capacity rarely falls so
much as 33 per cent. below the healthy standard, but it is never up to
the normal vital volume. This fact is most significant, especially
when it occurs in an individual whose relatives have succumbed to this
disease; but it rarely attracts sufficient attention from such persons
as to induce them to have their breathing capacity measured, much less
to take effective measures to bring and keep it up to the healthy
standard. So long as there are, to them, no tangible symptoms of
approaching mischief, and they feel fairly well, they act as if they
thought "that all men were mortal but themselves." Yet it is from
among persons who have an inherited but latent tendency to tubercular
disease, and whose lung power is below par, that the great army of
consumptives who die every year is recruited. It is very difficult to
induce persons who ought to be interested in this matter to take
effective measures for their future safety when the terrible symptoms
accompanying the last stages of the disease often fail to shake the
sufferer's confident expectation of recovery; and we sometimes see
them engaged in laying plans for the future when death is imminent. I
regret deeply to be obliged to make these statements, because I am
convinced that if the suggestions laid down in this work were
generally reduced to practice by those who have reason to dread the
development of tubercular disease, many valuable lives would be saved.