42 
MALARIA 
Fig. 1. The sporogonous and sehizogonous cycles of Plasmodium, falciparum. (From Protozoology 
by Thomson and Robertson through courtesy of Williams and Wilkins Company, publishers.) 
shape is now altered by indentations or out- 
pouchings, and pigment granules appear. 
The erythrocytes infected with this para¬ 
site, unlike vivax-infected red cells, do not 
enlarge as the parasite grows; if anything, 
they tend to shrink in size. Neither do 
they show the same alterations, viz., Schiiff- 
ner’s granules. They do, however, exhibit 
another type of stippling known as 
Maurer’s dots or Maurer’s clefts. These 
differ from Schuffner’s granules in that 
their incidence is usually not so common, 
they are generally darker, more of a brick 
red shade, are not usually as numerous, are 
quite irregular in size and shape, and are 
often larger. It frequently requires a some¬ 
what longer staining period or stronger 
staining solution than usual to bring them 
out. They are said to be more commonly 
present during the afebrile stage of the 
infection^ which would suggest their associ¬ 
ation with older parasites. Undoubtedly 
they represent a change in the erythrocyte 
effected by the growing parasite but the 
mechanism of this is not yet understood. 
The infected cell is often observed to stain 
more intensely. 
Actually these larger and irregular so- 
called “ring” forms are probably equiva¬ 
lent in age to the somewhat less than half- 
grown vivax parasites which we term 
amoeboid forms. Thomson and Robertson 
(1929) state that the trophozoites remain 
“in the peripheral blood in the ring form 
for at least 18-24 hours, possibly longer.” 
Prior to schizogony most of the tropho- 
