Page:Tropical Diseases.djvu/99

III] recognized or adequately described. Many regard them as but varieties of the common subtertian infection.

The parasite.—The parasites are said to be of two kinds (very generally in association), the pigmented, Laverania præcox (Plate II., Fig. 1), and the unpigmented, Laverania immaculata. In both the cycle is approximately one of twenty-four hours; in both the young parasites exhibit very active movements, and tend to assume the ring form. Before segmentation they grow so as to occupy from one-fifth

Chart 3.—Quotidian infection.

to one-third only of the corpuscle. Both form little heaps of from six to eight very minute spores.

In the unpigmented parasite hæmozoin is never seen unless it be in the crescent phase—a phase the occurrence of which has not been satisfactorily established; in this phase, however, hæmozoin is never absent. In the pigmented parasite there is a considerable amount of fine hæmozoin, which at the segmenting stage—rarely seen in peripheral blood—collects in the usual way into one or two more or less central clumps.

The fever.—The fever is such as just described, a typhoid-like depression being generally a prominent feature in well-marked cases (Chart 3).