Fully grown they only attain two-thirds or less of the diameter of the erythrocytes, which display an inclination to shrink and then appear darker than the normal (brass-coloured). In the early stage dots or stippling--sometimes called Maurer’s dots--appear on the blood corpuscles as in those attacked by the ordinary tertian parasite (_Plasmodium vivax_), but the Maurer’s dots are relatively coarse and few, and are not easily stained. These dots were first described by Stephens and Christophers in 1900, and subsequently by Maurer in 1902. About thirty hours after the entrance into the blood corpuscles, the parasites are rarely found in the peripheral blood, but they are present in the internal organs, and especially in the spleen. The schizogony, which now begins in the internal organs, proceeds on the same lines as that of the quartan parasite, that is, usually with the merozoites radially arranged around a central agglomeration of dark brown pigment. [Illustration: FIG. 87.--The pernicious malignant or sub-tertian parasite in the red corpuscles of man, asexual stages. (After Manson.)] The number of merozoites formed is quoted differently, _e.g._, 8 to 24, on an average 12 to 16. However, according to the recent cultural researches of J. G. and D. Thomson[204] (1913) the number of merozoites of _P. falciparum_ is 32. D. Thomson, from examination of spleen smears at autopsy, also concludes that the number of merozoites may reach 32. During their formation the blood corpuscle which is attacked gets paler and disintegrates. [204] _Proc. Roy. Soc._, B, lxxxvii, p. 77. [Illustration: FIG. 88.--The crescents of the malignant tertian parasite. (After Mannaberg.) See also fig. 81.] The gametocytes which finally appear are attenuated, curved bodies, rounded at each end and known as crescents (figs. 81, 88), and are provided with a nucleus and with coarse pigment masses. In the males the pigment is more scattered than in the females, where it is around the nucleus. Their length is 9 µ to 14 µ, and their breadth is 2 µ to 3 µ. At first they are still in the pale blood corpuscles, later they free themselves and are found in numbers in the peripheral blood in cases of pernicious malaria of Southern Europe and the tropics, while, on the other hand, they occur much more rarely in the peripheral blood in West African malignant tertian. Their further development takes place under the same conditions as in the other malarial parasites. [Illustration: FIG. 89.--Section through a tubule of the salivary gland of an _Anopheles_ with sporozoites of the malignant tertian parasites; on the left at the top a single sporozoite greatly magnified. (After Grassi).]