e earliest theories in regard to the cause of the
disease.

For instance, we find some of the very early writers emphasizing the
point that swampy localities should be avoided for they produce animals
that give rise to disease, or that the air is poisoned by the breath of
the swamp-inhabiting animals.

These views of the origin of the fever prevailed until about the
beginning of the eighteenth century when the recently discovered
microscope began to reveal the various kinds of animalculae to be found
in decaying material.

In 1718 Lancisi held that the myriads of insects, particularly gnats or
mosquitoes, that arose from such swampy regions might carry some of
these poisonous substances and by means of their proboscis introduce
them into the bodies of the people, and although he had made no
experiments to test the assumption he did not consider it impossible
that such insects might also introduce the smallest animalculae into the
blood. It took almost two centuries of study and investigation before
this guess was proved to be right.

One reason why the mosquitoes were not earlier associated with these
diseases was that all who investigated the matter at all turned their
attention to the bad condition of the air in these swampy regions.
Malaria means bad air. We all know that we can see the mists arising
from such regions, particularly in the evening or at night, and as
exposure to these mists very often meant an attack of malaria they were
naturally supposed to be the cause of the disease. So for a long time
the whole attention of investigators was turned toward studying and
analyzing these vapors, and various experiments were made which seemed
to show conclusively that the malaria was caused only by these
emanations. The investigations even went so far that the exact germs
that were supposed to cause the fever were separated and experimented
with.

THE PARASITE THAT CAUSES MALARIA

The blood had been studied time and again and the characteristic
appearance of the blood of a malarial patient was well known. In 1880
Laveran, a French army surgeon in Algiers, began to study the blood of
such patients microscopically and soon was able to demonstrate the
parasite that caused the disease. His discoveries were not readily
accepted, but other investigations soon confirmed his observations and
the fact was gradually firmly established. Not until recently, however,
did this distinguished physician receive a full recogn