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10 coiling-up movement, usually seen just before the microgamete finally ceases to move.

It is of importance to bear in mind that these flagellated bodies are never seen in newly drawn blood, and that they come into view only after the slide has been mounted for some time ten to thirty minutes, or even longer, according to circumstances.

Source of the flagellated body.—Careful observation shows that the flagellated bodies are developed from a particular phase of the intracorpuscular parasite, a phase which differs in form according to species namely, in certain types from what is known as the "crescent body"; in other types from certain large intracorpuscular parasites closely resembling the mature parasite (Fig. l, j) just prior to concentration of haemozoin and segmentation.

The crescent body.—These bodies, and consequently the flagellated body, are not present in the blood at the commencement of a malarial infection, or necessarily, especially if it be long delayed, at the commencement of the recrudescence of a latent infection. They come into the blood only after a week or ten days of acute clinical symptoms. At first few in number, and perhaps difficult to find, they gradually become more numerous and persist for days after the disappearance of the other forms of the parasite and the decline of the acute symptoms, and then gradually disappear. Unlike the other forms of the parasite, they are not affected by quinine. They may vanish from the blood after a week, or persist in it for six weeks or longer. They may be very numerous, several in every field of the microscope, or so scanty that many preparations may have to be searched before one is found. Not infrequently they cannot be discovered at all; especially is this the case in malignant (subtertian) infections in the tropics, although, strange to say, when the same patients suffer a relapse in Europe it is generally easy enough to find the crescent body in the blood.

The shape, size, and structure of the crescent body can best be comprehended from the illustration (Fig. 5). It exhibits no amoeboid movements.