The gametes show practically the characteristics of the benign tertian ones but are smaller.
Plasmodium Falciparum.—The young schizont of malignant tertian is extremely difficult to detect in fresh preparations, there being noted early in the rather long continued, hot stage, as small crater-like dots, about one-sixth of the diameter of a red cell which, however, show an active amoeboid movement.
Fig. 5.—Plasmodium vivax. Mature schizont and merocyte. Found in the blood just before and at onset of chill. X 2200. (MacNeal after Doflein.)
Malignant tertian blood tends to show rather marked vacuolation of the red cells and these central vacuoles have a resemblance to young ring forms. The malarial parasites are most often peripherally placed and they do not enlarge and diminish in size on focusing up and down as do the vacuoles.
Fig. 6.—Plasmodium malariae. (Quartan.) Development of nonsexual parasite in blood of man. X 2200. (From MacNeal after Doflein.)
Later on in the hot stage these ring-like dots enlarge to become about one-third of the diameter of a red cell, most often occupying the periphery of the infected red cell. About this time, or at the very commencement of the pigmentation, the schizont-containing red cells disappear from the peripheral circulation so that the further development is rarely observed in blood specimens.
The infected cell is brassy in color and shrunken in shape—it shows evidences of degeneration. The gametes appear as crescent-shaped bodies, which are absolutely characteristic of malignant tertian, the male gamete being more hyaline and delicate while the female one is more granular and larger.