Page:Tropical Diseases.djvu/47

I] in question was not efficient as regards another blood parasite of birds—namely, hæmoproteus—or as regards the malaria parasites of man. Thus, by direct observation and by analogy, Ross distinctly, and first, proved that the extracorporeal phase of the malaria parasite is passed in particular species of mosquitoes, and, by analogy, that the parasite is transferred from man to man by the mosquito.

MacCallum's discovery.—A gap in Ross's observations was filled in by MacCallum, who showed,



principally by observations on hæmoproteus, also a malaria-like parasite of birds, that the function of the filament after it breaks away from the parent sphere, or flagellated body, is to impregnate (Fig. 10, c, f) the granular crescent-derived spheres, which then become transformed into sharp-pointed travelling vermicules. Doubtless, although the process has not been directly observed, it is in virtue of the locomoting and penetrating properties of the travelling vermicule that the malaria parasite is enabled to lodge itself, where Ross first found it, in the stomach wall of the mosquito.