Page:Popular Science Monthly Volume 59.djvu/204

194 enter, and in which they repeat the cycle, thus bringing about autoinfection.

Another Italian naturalist, Golgi, in 1889, showed that the spore formation of the parasites and the well-known pyrexial attacks on the part of the patient occur at the same time, and the phenomena were interpreted as cause and effect. The direct cause of the attack was then found to be the liberation into the blood plasm of the melanin

The sporozoites penetrate epithelial cells {a) and grow to adult size. When ready to sporulate, they are free in the lumen of the organ. The nucleus divides repeatedly (b) and each of the ultimate sub-divisions becomes the nucleus of a merozoite (c). These re-enter epithelial cells (a) and repeat the cycle. After five or six days the merozoites have a different fate. Some (d—g) enlarge and form egg-cells; others (h—j) form minute flagellated male cells, or microgametes. One of these fuses with one egg cell, (g—k), and the copula then forms spores (k), each of which form, in turn, two sporozoites (l). In this condition the organism is taken into a new host and the process is then repeated.

granules, which, acting like a poison, throw the entire system into disorder. In different types of malaria, the attacks sometimes occur every 72 hours, sometimes every 48 hours, and in some cases at irregular intervals. These different effects are produced by slightly different forms of the malaria organism. One form, known as Plasmodium malariæ, sporulates every 72 hours; another, Plasmodium