The best minds of the profession had been attracted to a solution of the problem, but all in vain.

Commission after commission had been appointed, with negative results; various organisms had been described as the cause, and there were sad illustrations of the tragedy associated with investigations undertaken without proper training or proper technique.

By the year 1900, not only had the ground been cleared, but the work on insect-borne disease by Manson and by Ross had given observers an important clue.

It had repeatedly been suggested that some relation existed between the bites of mosquitoes and the tropical fevers, particularly by that remarkable student, Nott of Mobile, and the French physician, Beauperthuy.

But the first to announce clearly the mosquito theory of the disease was Carlos Finlay of Havana.