PARASITES IN MALARIAL FEVER 19 



granules are coarser and always black. The red cor- 

 puscles containing the benign tertian parasites are swollen 

 so that they are larger and paler than the average. In 

 a quartan infection they are slightly smaller, and very 

 slightly darker in colour than the average. 



If the blood be examined at intervals of a few hours 

 these developments are gradually seen to become more 

 pronounced. The parasites increase in size, more and 

 more pigment is formed, brown and fine in the tertian, 

 coarse and black in the quartan. The changes in the 

 red corpuscles become more marked (figs. 6 and 7). 



FIG. 7. a toy, Phases in the asexual development of the benign tertian 

 parasite Plasmodium vivax ; jc to z, phases in the sexual development. 



At length the parasites nearly fill the red corpuscles that 

 contain them ; this requires rather less than two days 

 with the tertian parasite, and less than three days with 

 the quartan. Amoeboid movements at this stage cease. 

 The full growth is thus accomplished, the pabulum 



