Fig. io. Plasmodium, the malarial parasite, 1-16, and • . the mosquito, 



17-22. 1, sporozoite, or form introduced by a mosquito bite into human blood; 

 2, the same free in the blood ; 3-5, changes which it undergoes in the red I l- 

 cell ; 6, merozoites or spores formed by division, with the attendant destruction of the 

 blood-cell; this - 6, may be repeated many times, but eventually 1 



develop in the blood-ce s into sexual forms; 7,8, 9, development of a macrogamete 

 or female element ; 7a, 8a, 9a, 9b, development of microgametes or male element ; 10, 

 conjugation of a macrogamete and a microgamete; 11. ookinet resulting from this 

 conjugation ; it must now enter the mosquito ; 12, ookinet at base of two cells in wall 

 of mosquito's stomach ; 13-16, transformation within the mosquito of an ookinet into 

 an oocyst filled with sporozoites; the sporozoite must then enter the human blood; 

 17-22, see Fig. 220. (After Leuckart-Chun's wall-chart, from Sedgwick's Sanitary 

 Science.) 



