FIG. 270. Life history of malaria parasite, Plasmodium pracox. i, sporozoite, introduced 

 by mosquito into human blood; the sporozoite becomes a schizont. 2, young schizont, 

 which enters a red blood corpuscle. 3, young schizont in a red blood corpuscle. 4, full- 

 grown schizont, containing numerous granules of melanin. 5, nuclear division preparatory 

 to sporulation. 6, spores, or merozoites, derived from a single mother-cell. 7, young macro- 

 gamete (female) , derived from a merozoite and situated in a red blood corpuscle, 70, young 

 microgametocyte (male) derived from a merozoite. 8, full-grown macrogamete. 8a, full- 

 grown microgametocyte. In stages 8 and 8 a the parasite is taken into the stomach of a 

 mosquito; or else remains in the human blood, g, mature macrogamete, capable of fertiliza- 

 tion; the round black extruded o'bject may probably be termed a "polar body." ga, mature 

 microgametocyte, preparatory to forming microgametes. gb, resting cell, bearing six flagellate 

 microgametes (male). 10, fertilization of a macrogamete by a motile microgamete. The 

 macrogamete next becomes an ookinete. n, ookinete, or wandering cell, which penetrates 

 into the wall of the stomach of the mosquito. 12, ookinete in the outer region of the wall of 

 the stomach, i. e., next to the body cavity. 13, young oocyst, derived from the ookinete. 

 14, oocyst, containing sporoblasts, which are to develop into sporozoites. 15, older oocyst. 

 id,, mature oocyst, containing sporozoites, which are liberated into the body cavity of the 

 mosquito and carried along in the blood of the insect. 77, transverse section of salivary gland 

 of an Anopheles mosquito, showing sporozoites of the malaria parasite in the gland cells 

 surrounding the central canal. 



1-6 illustrate schizogony (asexual production of spores);- 7-i6,sporogony (sexual production 

 of spores). 



After GRASSI and LEUCKART, by permission of Dr. Carl Chun. 



235 



