i6o 



THE PROTOZOA 



Conjugation in the malaria-causing organism {Plasmodium malaria) 

 is bound up with a change of hosts, thus giving a complicated life- 

 history, which may, and probably does, occur in other kinds of 

 Sporozoa as well, although the phenomenon has been only recently 

 made known. 



Fig. 88. — Life-history of a Coccidium. [SCHAUDINN.] 

 a, b, c, schizonts and asexual reproduction (schizogony). The merozoites at c repeat the cycle 

 or pass on to the following stages, d, e,f, development of the female or macrogamete. h, i,J, 

 development of the male flagellated gametes; g, copulation of the male and female gametes; k 

 and 1, stages in the formation of the four spores and sporozoites. 



The sporozoon which is now positively known to be the cause of 

 " malarial disease," lives in the human blood under various forms, 

 which may possibly be distinct species differing from one another in 

 the number of spores produced and in the pathogenic effects. Sev- 

 eral varieties at least have been described and specially named on 

 account of minute differences, but it is probable that these can be 



