Page:Tropical Diseases.djvu/91

III] Although the individual attacks are very amenable to quinine, the infection appears to be of a more persistent nature than that of tertian and subtertian malaria; attacks, therefore, are prone to recur during several years.

The parasite.—The early stage of the benign tertian parasite, Plasmodium vivax (Plate I., Fig. 2),

Chart 1.—Quartan ague.

resembles that of the quartan inasmuch as it consists of a small pale speck on, or in, the invaded red blood-corpuscle (Plate I., Fig. 2, a); it differs in exhibiting very much greater amœboid activity, changing its form and location in the corpuscle incessantly, besides pushing out and retracting pseudopodia (Plate I., Fig. 2, b). This amœboid activity persists during growth and the formation of hæmozoin, though in a progressively diminishing degree; it gives rise to great and rapidly