TERTIAN MALARIA 



645 



of six to twelve spores (/). The quartan parasite does not 

 form crescents, and the flagellated bodies (h), which 

 are rarely seen, are developed from large pigmented 

 parasites. 



(2) Benign, or spring, tertian fever (Fig. 62 ; Plate 

 XXVII, 6). This is the commonest form of malaria. 

 The benign tertian parasite (Plasmodium vivax) completes 

 its asexual life-cycle in forty-eight hours, an attack 

 occurring every other day, or, reckoning the day of the 



FIG. 62. The benign tertian parasite : a, b, c, d, amcebulae ; e, sporo- 

 cyte ; /, free spores ; g, female gametocyte with so-called polar 

 bodies ; h, male gametocyte. (After Rees.) 



previous attack, every third day. In the early stage it 

 resembles the quartan, but shows much more active 

 amoeboid movement. The pigment-granules are also finer 

 than in the quartan, and incessantly change their position. 

 The parasite finally invades the whole corpuscle, which 

 becomes enlarged and pale. Enlargement of the corpuscles 

 is a marked feature in the benign tertian infection (d). 



Segmentation takes place, but is symmetrical (e), 

 resulting in the formation of a grape-like cluster of twelve 

 to twenty spores (/). As in the quartan, no crescentic 

 bodies are developed, and the gametocytes (g, h) are 

 similar to, but larger than, the quartan (Plate XXIX, a). 



