The diagnosis of malaria, like its pathogenesis, has a scientific life of scarcely two decades. The subject has been roughly handled since an acquaintance with its microscopic diagnostic methods has reached the general profession from the laboratories of scientific biologists and clinicians. As in all newly developed methods, medical and otherwise, there is a tendency to swing from one extreme to the other. Great skepticism greeted Laveran's initial reports that certain parasitic elements existing in the blood of malarial patients and hitherto confused with pigment-bearing leucocytes, were the cause of malaria. The general skepticism of Laveran's colleagues is now superseded by equally universal credulity. While previously no parasites were admitted, now they are even confused with the constituents of the normal blood. Five years ago the existence of malaria in Chicago was denied, while today many vague diseases, especially obscure or obstinate fevers, are diagnosticated malaria.
I. DIAGNOSIS OF THE