Being an animal, the plasmodium naturally would not grow upon culture-media like the vegetable bacilli and bacteria, and this very fact had delayed its recognition, but raised at once the probability that it must be conveyed into the human body by some other animal. Obviously, the only animals that bite our human species with sufficient frequency and regularity to act as transmitters of such a common disease are those Ishmaelites of the animal world, the insects. As all the evidence pointed toward malaria being contracted in the open air, attested by its popular though unscientific name _mal-aria_, "bad air," and as of all forms of "bad air" the night air was incomparably 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.