778 THE ILEMATOZOON OF MALARIA 



epithelial cells lining the mucous membrane, again changes to the spherical 

 shape and forms a small cyst in the muscular wall. Measuring at first 

 6/A in diameter it gradually grows, lifting the outer wall of the stomach and 

 forming an hernia into the body cavity of the insect, until it ultimately 

 attains a diameter of 60-80/z. Its chromatin is collected into a central mass. 

 Changes now begin, culminating in the formation of the oocyst. The 

 chromatin splits into numerous small fragments which, passing to the peri- 

 phery and becoming surrounded with protoplasm, form the sporoblasts 

 (fig. 375). From the sporoblasts are formed the sporozo'ites , which are at first 

 spherical but subsequently elongate and become pointed at the ends. Then 

 the oocyst bursts (fig. 376) and the sporozo'ites are set free into the body cavity 

 of the mosquito, from whence they are swept along by the circulation into the 

 thorax and head and invade especially the salivary glands. When an 

 Anopheles mosquito thus infected bites a healthy individual it inoculates 

 into the victim's blood both its venin and these sporozoites. The sporozoites 

 act as merozoi'tes, infect the red cells and give rise to intra-corpuscular 

 spherical amoeboid parasites. 



FIG. 375. The hsematozoon of malaria. FIG. 376. The haematozoon of malaria. A 



Ripe oocyst. (After Grassi.) ruptured oocyst from which the sporozo'ites are 



escaping. (After Grassi.) 



The different species of haematozoa found in malaria. 



Golgi, Grassi and Feletti, and other Italian observers have for a long time 

 considered that there is more than one species of the malarial hsematozoon 

 and the majority describe three, corresponding to the parasites of quartan, 

 tertian and the irregular tropical fevers. Manson however considers that 

 there are five species corresponding to as many different clinical types of 

 the disease. 



In the present chapter Golgi's classification will be followed. 



FIG. 377. Life history of the malarial parasite (after Grassi and Schaudinn). 



A. Schizogony. I. A free sporozoite. 2. A sporozoite entering a red cell. 

 3, 4, 5, 6. Growth of the intracorpuscular amoeboid parasite preceding multipli- 

 cation and division into merozoites. 7. Merozoites which have burst the red cell 

 and become free in the blood stream. Some merozoi'tes penetrate other red 

 cells and pass through the same series of changes (1-7) others become gametes. 



B. Sporoaony.Q&'Usi. Growth and differentiation of the female cell or 

 macrogamete 9b-13b. Growth and differentiation of the male cell or micro- 

 gametocyte. 14b. Budding off of microgametes from the microgametocyte. 

 15b. Free microgamete or flagellated body. 16. Fertilization of the macro- 

 gamete by the microgamete. 17. The fertilized cell or zygote (ookinete). 18. 

 Infection of the epithelial cells lining the walls of the mosquito's stomach. 19-24. 

 Growth and development of the oocyst and formation of sporozoites within it. 

 25-27. Rupture of the oocyst, and discharge of the sporozoites which travel to 

 the salivary glands of the mosquito . 1 . Discharge of a sporozoite from the mouth 

 dunng biting. (From Mense's Handbuch der Tropenkrankheiten.) 



