ILLUSTRATIONS. 



Plate I. 



Fig. 1. Plasmodium petheci sp. nov. Ringform like the tropical pla3modiuni. 



2. Amoeboid form with vacuole. 



3. Double infection. 



4. Adult form with pigment granules and differentiated chromatin. 



5. Mierogametes like quartan parasites. 



6. Macrogametes like quartan parasites. 



7. Schizogony according to the type of the human tertian parasite. 



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