88 



PROTOZOA 



nearly fills it. The parasite then sporulates. The rupture of the cyst 

 formed in sporulation, accompanied by the rupture of the wall of the 

 corpuscle, liberates numerous spores in the fluid of the blood. These 

 enter other corpuscles and pass through a similar life history. The setting 

 free of spores from many infected corpuscles corresponding to the starting 



^f In reef ^/^o^ ^^^ 



^o, 



^-^ 



Asexual 

 cycle 

 in man 



Asexual spore 



Eni^r^ man 



Gamefo- 

 cyfes 



Enfer_rnc>5^ifp_._, 



-Sexual 

 spore 



Sexual cycle 



in mosquito 



Macro- |^^8 

 gamefe- 



Sporoblasf 



Ookinete 



13 Oocyst 



Fig. 33. — Diagram of the life cycles of the malarial parasite of the tertian type, show- 

 ing the asexual cycle in man and the sexual cycle in an anopheline mosquito. Stages 1 to 6 

 show the entrance of the spores into a red blood corpuscle and the growth and sporulation 

 of the parasite; stage 7, the production of gametocytes; stage 8, their transformation into 

 gametes; stages 9 and 10, fertilization and the zygote; stages 11 and 12, the change of the 

 zygote to an active form, the ookinete, which penetrates the wall of the stomach and encysts; 

 stage 13, forming an ooajst below the outer layer of the stomach wall; stages 14 and 15, 

 the development of several sporoblasts in the oocyst, the development from each of many 

 spores, and their dispersal into the body cavities; and stage 16, the entrance of these spores 

 into the salivary gland. They are introduced with the saliva into a human being, stage 17, 

 enter red blood corpuscles, and another cycle is begun. 



of a new generatfon, is accompanied by the liberation of poisons in the 

 blood which cause an attack of chills and fever. The time between these 

 attacks, therefore, indicates the period between generations of the 

 parasite. These intervals are 24, 48, or 72 hours, corresponding to three 

 forms of the disease known respectively as pernicious, tertian, and quartan 

 malaria. 



In addition to these spores, there are also produced within the red 

 corpuscles spores which become sexual in character and by means of which 



