The Comparative Morphology of the Sporozoites of the Human Species of Plasmodium, Marchiafava and Celli, 1885

The sporozoites figured in Plates I, II, and III were traced from camera lucida drawings. Those in Plates I and III were made from smears prepared from the salivary glands of specimens of Anopheles quadrimaculatus in which infections had just matured. Glands were crushed in a small drop of albumin water, spread and fixed in hot sublimate alcohol. They were then stained, either with iron hematoxylin or with Giemsa's stain. Those in Plate II were from glands which had been crushed in saline, air dried, fixed in the methyl alcohol of Wright's stain, and stained with the latter. We have never observed any motility of sporozoites, in the sense of locomotion, in unfixed fluid preparations made from the salivary glands. In unfixed fluid preparations of stomachs, in which sporozoites were escaping from mature cysts, a very active vibratory movement of groups or masses of sporozoites is noted, but we have not been able to distinguish the source of the motion. It has not been possible to discern the contribution made by any of the individuals comprising the group. In some of these preparations, there has been a suggestion that sporozoites isolated in the fluid were progressing by a very slow gliding movement. Most sporozoites in gland preparations finally undergo an imperceptible flexation without any change of location. This is probably a degenerative change. Sporozoites are long slender organisms, with a length from 10 to 30 times their diameter. In general their diameter is uniform, but some individuals appear to be enlarged in the middle portion, while others have a greater diameter toward one extremity. The length is subject to great variation, although the limits of variation among those secured