own in
America, but sought in vain: there had at that time been no systematic
study. The fundamental study which set us on the track was a
demonstration by Patrick Manson,(3) in 1879, of the association of
filarian disease with the mosquito. Many observations had already
been made, and were made subsequently, on the importance of insects as
intermediary hosts in the animal parasites, but the first really great
scientific demonstration of a widespread infection through insects was
by Theobald Smith, now of Harvard University, in 1889, in a study of
Texas fever of cattle.(4) I well remember the deep impression made upon
me by his original communication, which in completeness, in accuracy of
detail, in Harveian precision and in practical results remains one of
the most brilliant pieces of experimental work ever undertaken. It is
difficult to draw comparisons in pathology; but I think, if a census
were taken among the world's workers on disease, the judgment to be
based on the damage to health and direct mortality, the votes would be
given to malaria as the greatest single destroyer of the human race.
Cholera kills its thousands, plague, in its bad years, its hundreds of
thousands, yellow fever, hookworm disease, pneumonia, tuberculosis,
are all terribly destructive, some only in the tropics, others in more
temperate regions: but malaria is today, as it ever was, a disease to
which the word pandemic is specially applicable. In this country and in
Europe, its ravages have lessened enormously during the past century,
but in the tropics it is everywhere and always present, the greatest
single foe of the white man, and at times and places it assumes the
proportions of a terrible epidemic. In one district of India alone,
during the last four months of 1908, one quarter of the total population
suffered from the disease and there were 400,000 deaths--practically
all from malaria. Today, the control of this terrible scourge is in our
hands, and, as I shall tell you in a few minutes, largely because of
this control, the Panama Canal is being built. No disease illustrates
better the progressive evolution of scientific medicine. It is one of
the oldest of known diseases. The Greeks and Graeco-Romans knew it well.
It seems highly probable, as brought out by the studies of W.H.S. Jones
of Cambridge, that, in part at least, the physical degeneration in
Greece and Rome may have been due to the great increase of this disease.
Its clinical m