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118 tested by it. In many forms of malarial disease, if life is to be saved, action must be prompt, decisive, energetic, and based on accurate diagnosis. The diagnosis of ordinary agues may be postponed for a day or two without much danger, and be made correctly enough without the microscope; but every now and again a pernicious attack is sprung upon the practitioner, the nature of which he must be able to recognize at once, and recognize with confidence. When the parasite is seen in the blood, it is surely known that there is a malarial element in the case and that quinine is indicated. Confidence in directing treatment is a great matter. It cannot, therefore, be too strongly urged on the tropical practitioner to avail himself of every opportunity to gain experience in the use of the microscope in blood examinations, and to take care to have a suitable instrument in working order and available at a moment's notice. The practical difficulties in carrying out this recommendation are insignificant in comparison with the importance of the results. With practice, five minutes usually suffices to effect a positive microscopical diagnosis of malaria. Every tropical practitioner should be provided with a travelling microscope, or, at least, carry about with him a few microscope slips for blood films. He must be on his guard, however, against concluding from the discovery of malaria parasites in his films that malaria is necessarily the only, or even the principal, disease his patient is suffering from.