changing irregularities in the contour of the parasite (Plate I., Fig. 2, c, d, e), but is almost entirely suspended by the time hæmozoin-concentration is effected. In the tertian parasite the hæmozoin particles are, on the whole, finer than those of the quartan parasite; and, moreover, are in a state of much more active and incessant movement, constantly changing their position in the peripheral region in which they, for the most part, seem to lie (Plate I., Fig. 2, f). Another, and highly characteristic, accompaniment of tertian infection is the considerable hypertrophy and marked decoloration of the corpuscles containing the parasite (Plate I., Fig. 2, d, e, f , g). Sometimes the affected corpuscles seem nearly twice the diameter of the healthy ones; and nearly always, if the parasite is of any magnitude, the rim of hæmoglobin has a "washed-out" look, sometimes being almost colourless.
In corpuscles invaded by the tertian parasite, deep coloration with Leishman's or Giemsa's stains brings out a feature which does not occur in those attacked by quartan or subtertian parasites. With these stains in tertian-invaded corpuscles the hæmoglobin is speckled with chromophilic particles called " Schüffner's dots." This is a feature of some diagnostic value. In the very young phases of the parasite it is not always present; unfortunately for its diagnostic value, these are just the phases that are difficult to diagnose from quartans and subtertians.
In the tertian parasite, when segmentation is completed, the resulting body, instead of the very symmetrical, daisy-like figure of the quartan, resembles rather a cluster of grapes in some more or less central part of which one or two masses of dark pigment have accumulated among the berries (Plate I., Fig. 2, h; also Figs. 1 and 2, b). The little spherules forming the cluster fifteen to twenty-six in number are smaller, smoother, and more spherical than those of the quartan parasite; seldom, in the unstained condition, exhibiting their nuclei. I believe that in natural, uncompressed conditions the tertian "rosette," as it is called, tends to pass from the disc form,
