It first appears as a very minute colorless body with active amoeboid movements, and increases in size, attacks a succession of corpuscles, and finally attains a size as large as or larger than a corpuscle.

The corpuscles attacked become pale by the destruction of haemoglobin, swell up and disintegrate, the haemoglobin becoming converted into granules of black pigment inside the parasite.

Having attained a definite size the organism forms a rosette and divides into a number of forms similar to the smallest seen inside the corpuscles; these small forms enter other corpuscles and the cycle again begins.
This cycle of development takes place in forty-eight hours, and segmentation is always accompanied by a paroxysm of the disease shown in a chill followed by fever and sweating which is due to the effect of substances liberated by the organism at the time of segmentation.

A patient may have two crops of the parasite developing independently in the blood, and the two periods of segmentation give a paroxysm for each, so that the paroxysms may appear at intervals of twenty-four hours instead of forty-eight (Fig.

20).