PLATE VI. 



O 





FIGS, i, 2, and 3 show three phases of the parasite of tertian fever. 

 Fig. i, ring form, showing beginning pigment formation. Fig. 2, full- 

 grown parasite. Fig. 3, segmenting bodies. (WELCH and THAYER.) 



FIGS. 4, 5, and 6 show the parasite of quartan fever at different stages of 

 growth. Fig. 4, moderately developed iutracorpuscular parasite. Fig. 5, 

 large swollen extracorpuscular form. Fig. 6, flagellate body. (WELCH 

 and THAYER.) 



FIGS. 7, 8, and 9 illustrate the aestivo-autumnal parasite. Fig. 7, ring-like 

 body, with a few pigmented granules. Fig. 8, crescent still in blood-cor- 

 puscle. Fig. 9, vacuolatiou of crescent. (WELCH and THAYER.) 



FIG. 10. Amoeba from section of intestine hardened 'in alcohol and 

 stained with methylene blue. (COUNCILMAN and L,AFLEUR.) 



