The Human Malarial Parasites 



535 



a distinct blue dot, and the center appears colorless and like 

 a vacuole. The dot is usually on the side of the vacuole that 

 has the thinner protoplasmic outline. The smallest such 

 rings usually have a diameter equal to about ^ the diameter 

 of the blood-corpuscle. The tiny ring-form, or, as it might 

 better be called, the "seal-ring form," continues until the 

 schizont becomes half the diameter of the blood-corpuscle, 

 when its protoplasm has begun to increase so rapidly that 

 the vacuole no longer appears to be so conspicuous. The 

 organism also becomes irregular in shape and is actively 



Fig. 176. Parasite of tertian malarial fever: a, b, c, d, e, f, g, Grow- 

 ing pigmented parasite in the red blood-corpuscles; h, spores formed 

 by segmentation of the parasite no rosette is formed, but concentric 

 rings of the cytoplasm divide; i, macrogametocyte; ;, microgametocyte 

 with flagella. 



ameboid, its protoplasm streaming this way and that when 

 examined in fresh blood. At this time it may be noticed 

 that the infected blood-corpuscle is increasing in volume, 

 sometimes becoming twice the normal size, and also becoming 

 pale in color. It seems also as though the disk shape of the 

 corpuscle was lost, and it had become swollen into a more 

 spherical sometimes irregular form. The parasite, which 

 may still show a relic of its original ring- form, now shows plen- 

 tifully throughout its protoplasm exceedingly fine granules of 

 yellow-brown pigment. When from thirty-six to forty hours 

 old, all trace of the " seal-ring " form disappears, the ame- 



