PROPHYLAXIS OP MALARIA. 
27 
in this species, ameboid motility is entirely absent. At this time 
the fully developed parasite fills slightly more than half of the in¬ 
fected cell, the pigment is collected at the center in a small compact 
almost black mass, and radial striations are noted dividing the para¬ 
site into from 10 to 15 segments or merozoites. In some instances 
as high as 21 merozoites have been observed. Sporulation occurs 
within the red blood corpuscle and considerable of the infected cell 
is still undestroyed at the time that sporulation begins. The spor- 
ulating forms occur very rarely in the peripheral blood, but are 
present in large numbers in the capillaries of the internal organs, 
notably the spleen, liver, and brain, and in the bone marrow. 
In stained preparations, using the Wright method, the staining 
reactions are the same as occur in Plasmodium vivax and Plasmo¬ 
dium malaria >, the differential diagnosis resting upon certain mor¬ 
phological features to be noted later in this contribution. 
Morphology of Plasmodium falciparum quotidianum. Quotidian 
esttco-autumnal plasmodium (Schizogony or Human Cycle). —The 
quotidian estivo-autumnal plasmodium, in the living condition, is 
noticed fust within or upon the red blood corpuscle as a very minute 
ring-shaped or disk-like hyaline body, which upon close inspection is 
seen to have a very active ameboid motion, the periphery of the 
parasite continually changing in appearance, due to the protrusion 
and retraction of minute pseudopodia. The outline of the organism 
at first is indistinct, but becomes more distinct as growth proceeds, 
and when the parasite is fully developed the outline is very clear cut 
and the organism is very refractive. The infected red corpuscle is 
generally smaller in size than the normal corpuscle, darker green or 
“ brassy ” in color, and frequently crenated, and in many instances 
triple infection of the corpuscle is observed. In the peripheral blood 
the hyaline, round or “ ring-shaped ” organisms are those which 
are most frequently observed, although a small number of the 
younger pigmented forms are not uncommon. The pigment consists 
of a small, solid block or mass, almost black in color, situated at 
some portion of the periphery of the parasite, or at the center, and 
is never motile. Very rarely the pigment consists of fine granules, 
but the granules never number more than three or four. 
In this species of plasmodium sporulation occurs at the end of 24 
hours, and the sporulating forms are very rarely observed in the 
peripheral blood, although blood from the spleen taken at the proper 
time will present numerous segmenting organisms. Just before 
sporulation the plasmodium occupies a little more than one-fourth 
of the infected corpuscle, thus easily distinguishing it from Plas¬ 
modium vivax or Plasmodium malaria which entirely fill the red 
blood cell when fully developed. As sporulation begins the pigment 
