the young, of the weak rather than the
strong.

FOOTNOTES:
[1] The term exudation is used to designate the
passing of cells and fluid from the vessels in inflammation; the
material is the exudate.

[2] By transudation is meant the constant interchange between
the blood and the tissue fluid.

CHAPTER V

INFECTIOUS DISEASES.--THE HISTORICAL IMPORTANCE OF EPIDEMICS OF
DISEASE.--THE LOSSES IN BATTLE CONTRASTED WITH THE LOSSES IN ARMIES
PRODUCED BY--INFECTIOUS DISEASES.--THE DEVELOPMENT OF KNOWLEDGE OF
EPIDEMICS.--THE VIEWS OF HIPPOCRATES AND ARISTOTLE.--SPORADIC AND
EPIDEMIC DISEASES.--THE THEORY OF THE EPIDEMIC CONSTITUTION.--THEORY
THAT THE CONTAGIOUS MATERIAL IS LIVING.--THE DISCOVERY OF BACTERIA BY
LOEWENHOECK IN 1675.--THE RELATION OF CONTAGION TO THE THEORY OF
SPONTANEOUS GENERATION.--NEEDHAM AND SPALLANZANI.--THE DISCOVERY OF
THE COMPOUND MICROSCOPE IN 1605.--THE PROOF THAT A LIVING ORGANISM IS
THE CAUSE OF A DISEASE.--ANTHRAX.--THE DISCOVERY OF THE ANTHRAX
BACILLUS IN 1851.--THE CULTIVATION OF THE BACILLUS BY KOCH.--THE MODE
OF INFECTION.--THE WORK OF PASTEUR ON ANTHRAX.--THE IMPORTANCE OF THE
DISEASE.

These are diseases which are caused by living things which enter the
tissues of the body and, living at the expense of the body, produce
injury. Such diseases play an important part in the life of man; the
majority of deaths are caused directly or indirectly by infection. No
other diseases have been so much studied, and in no other department
of science has knowledge been capable of such direct application in
promoting the health, the efficiency and the happiness of man. This
knowledge has added years to the average length of life, it has
rendered possible such great engineering works as the Panama Canal,
and has contributed to the food supply by making habitation possible
over large and productive regions of the earth, formerly uninhabitable
owing to the prevalence of disease. It is not too much to say that our
modern civilization is dependent upon this knowledge. The massing of
the people in large cities, the factory life, the much greater social
life, which are all prominent features of modern civilization, would
be difficult or impossible without control of the infectious diseases.
The rapidity of communication and the increased general movement of
people, which have developed in equal ratio with the massing, would
serve to extend widely every local outbreak of infection. The
principles underlyin