the
worst, it must be some insect which flew and bit by night; which by
Sherlock Holmes's process promptly led the mosquito into the dock as the
suspected criminal. It wasn't long before he was, in the immortal
language of Mr. Devery, "caught with the goods on"; and in 1895 Dr.
Ronald Ross, of the Indian Medical Service, discovered and positively
identified the plasmodium undergoing a cycle of its development in the
body of the mosquito. He attempted to communicate the disease to birds
and animals by allowing infected mosquitoes to bite them, but was
unsuccessful. Two Italian investigators, Bignami and Grassi, saw that
the problem was one for human experiment and that nothing less would
solve it. Volunteers were called for and promptly offered themselves.
Their blood was carefully examined to make sure that they were not
suffering from any latent form of malaria. They then allowed themselves
to be bitten by infected mosquitoes, and within periods varying from six
to ten days, eight-tenths of them developed the disease. It may be some
consolation to our national pride to know that although the organism was
first identified in the mosquito by an Englishman and its transmission
to human beings in its bite by Italians, the first definite and
carefully worked-out statement of the relation of the mosquito to
malaria was made by an American, King of Washington, in 1882; though it
is only fair to say that suggestions of the possible connection between
mosquitoes and malaria had, so to speak, been in the air and been made
from scores of different sources, from the age of Augustus onward.

Another mystery was solved--and what a flood of light it did pour upon
our speculations as to the how and wherefore of the catching of malaria!
In some respects it curiously corroborated and increased our respect for
popular beliefs and impressions. While "bad air" had nothing to do with
causing the disease, except in so far as it was inhabited by songsters
of the _Anopheles_ genus, yet it was precisely the air of marshy places
which was most likely to be "bad" in this sense. So that, while in one
sense those local wiseacres, who would point out to you the pearly mists
of evening as they rose over low-lying meadows and bottom-lands, and
inform you that there before your very eyes was the "mylary just
a-risin' out of the ground," were ludicrously mistaken, in another their
practical conclusion was absolutely sound; for it is in just such air,
a