bacillus of tuberculosis.
Every year more than one hundred and twenty-five thousand people of the
United States die because they are unable to withstand its persistent
attacks; five million Americans now living are doomed to death at the
hands of these executioners, and the figures must be more than doubled to
cover the casualties on the human side in the battles with the regiments
of all the species of bacteria causing disease.

The competition between and among the individuals of one and the same
species is the third part of the struggle for existence, and it is often
unsurpassed in its ferocity. When two lion cubs of the same litter begin
to shift for themselves, they must naturally compete in the same
territory, and their contest is keener than that which involves either of
them and a young lion born ten or fifteen miles away. The seeds of one
parent plant falling in a restricted area will be engaged in a competitive
struggle for existence that is much more intense than many other parts of
nature's warfare. In brief, the intensity of the competition will be
directly proportional to the similarity of two organisms in constitution
and situation, and to the consequent similarity of vital welfare. The
interests of the white man and the Indian ran counter to each other a few
hundred years ago, and the more powerful colonists won. The assumption of
the white man's burden too often demonstrates the natural effect of
diversity of interest, and the domination of the stronger over the weaker.
In any civilized community the manufacturer, farmer, financier, lawyer,
and doctor must struggle to maintain themselves under the conditions of
their total inorganic and social environments; and in so far as the object
of each is to make a living for himself, they are competitors. But the
contest becomes more absorbing when it involves broker and broker, lawyer
and lawyer, financier and magnate, because in each case the contestants
are striving for an identical need of success.

Although the severity of the conflict imposed by nature is somewhat
modified in the case of social organisms, where community competes with
community and nation with nation, no form of social organization has yet
been developed where the individual contest carried on by the members of
one community has been done away with. It is an inexorable law of nature
that all living things must fight daily and hourly for their very lives,
because so many are brought into t