This is one of those fairy tales of science which people are inclined to doubt, but any one who has worked at the subject and taken the trouble to go through the long series of preparations which have been sent home from India can not for a moment have the slightest doubt that what Ross stated was absolutely true, and that not only for bird but for human malaria. So soon as the idea got abroad that the key to the way in which the malarial parasite is propagated had been found the Italians immediately set to work with renewed vigor and with the utmost skill. Almost at once they demonstrated that what happened in the case of Ross’s sparrows happened also with the human subject: that the appropriate species of mosquito fed upon the human malarial subject and subsequently allowed to feed upon a non-malarial subject conveyed the malarial parasite and malarial disease, and that the appropriate species of mosquito belonged to the genus anopheles. There can not be the slightest doubt that the mosquito acts the part of transmitting agent as well as definitive host of the malarial parasite. This is a piece of knowledge of the utmost importance to mankind, for we know that malarial disease in tropical countries--which, after all, in the future will be the most important parts of the world, seeing that they can produce more food than temperate countries and can therefore support a larger population--causes more deaths and more disposition to death by inducing cachectic states predisposing to other affections than all the other parasites affecting mankind put together. We know now in what way this parasite is acquired. Depend upon it, in time, in virtue of this knowledge, we will get enormous power over the disease and sooner or later we will be able to prevent the infection of man by the parasite. It is only a question of study and the application of the knowledge already acquired, only a question of money and perseverance and a little ingenuity, and these results will come. It may not be in ten years or twenty years, but sooner or later the energies of a considerable portion of scientific mankind now being expended in endeavoring to devise means for preventing the infection of men with the malarial germ by the mosquito will bear valuable fruit.