374 



THE ETIOLOGY OF TROPICAL DISEASES 



irregularities in the condition of the corpuscle, which becomes swollen, 

 pale in colour, and may show deeply-stained " spots." The pigment 

 granules are finer than in the quartan parasite. The final 



FIG. 30. Tertian Malaria Parasite. 



decolonisation of the corpuscle is very marked. The "rosette 

 body" or sporocyte in this species is composed of some fifteen to 

 twenty-five spores, small, smooth, and oval; the gametes are 

 spherical. The benign tertian parasite is probably the commonest 

 form found in malaria, and is widely distributed over the globe. 



(c) The Malignant Infections (sestivo - autumnal, malignant 

 quotidian, malignant tertian). The amcebulce in these conditions 

 are much smaller than in the benign types, but may occur in pro- 

 digious numbers, and their movements are very active. The organism 

 causes considerable modifications in the shape and size of the corpuscle, 

 which has a tendency to shrivel. It is not filled by the parasite in the 

 same degree as in the other forms. Sporulation occurs in the spleen 



FIG. 31. Malignant Malaria Parasite. 



and other internal organs, and not in the blood, and, therefore, the 

 sporocytes in this form are not found in the blood in the usual way. 

 The most distinctive feature of all is that the malignant parasites 

 (gametes) form "crescents," and attack a larger proportion of red 

 corpuscles than in the other forms. The classifications, minor 



