take care of
themselves. The bacilli are not the only ones who can be numbered in
their billions. If there are billions of them there are billions of us.
We are not mere units--scarcely even individuals--except in a broad and
figurative sense. We are confederacies of billions upon billions of
little, living animalcules which we call cells. These cells of ours are
no Sunday-school class. They are old and tough and cunning to a degree.
They are war-worn veterans, carrying the scars of a score of victories
written all over them. _They_ are animals; bacteria, bacilli,
micrococci, and all _their_ tribe are _vegetables_. The daily business,
the regular means of livelihood of the animal cell for fifteen millions
of years past has been eating and digesting the vegetable. And all that
our body-cells need is a little intelligent encouragement to continue
this performance, even upon disease germs; so that we needn't be afraid
of being stampeded by sudden attack.

The next cheering find was that the worst enemies of the bacillus were
our best friends. Sunlight will kill them just as certainly as it will
give us new life. The germs of tuberculosis will live for weeks and even
months in dark, damp, unventilated quarters, just precisely such
surroundings as are provided for them in the inside bedrooms of our
tenements, and the dark, cellar-like rooms of many a peasant's cottage
or farmhouse. In bright sunlight they will perish in from three to six
hours; in bright daylight in less than half a day. This is one of the
factors that helps to explain the apparent paradox, that the dust
collected from the floors and walls of tents and cottages in which
consumptives were treated was almost entirely free from tuberculous
bacilli, while dust taken from the walls of tenement houses, the floors
of street-cars, the walls of churches and theatres in New York City, was
found to be simply alive with them. One of the most important elements
in the value of sunlight in the treatment of consumption is its powerful
germicidal effect.

CHAPTER VII

TUBERCULOSIS, A SCOTCHED SNAKE

II

Closely allied to the discovery that sunlight and fresh air are fatal to
the microoerganisms of tuberculosis came the consoling fact that these
bacilli, though most horribly ubiquitous and apparently infesting both
the heavens above and the earth beneath, had neither wings nor legs, and
were absolutely incapable of propelling themselves a fraction of an
inch.