26 
PROPHYLAXIS OF MALARIA. 
The merozoites or spores consist of a deep blue stained mass of 
cytoplasm containing a compact clump of dark red chromatin situ¬ 
ated somewhere near the periphery. In most instances the mass of 
chromatin is surrounded by a clear, unstained halo representing the 
unstained portion of the nucleus. 
Morphology of Plasmodium falciparum. Tertian estivo-outumnal 
plasmodium (Schizogony or Human Cycle'). —As I have stated, I 
believe that there are two distinct varieties of the estivo-autumnal 
plasmodium, the tertian and quotidian. These are distinguishable 
microscopically, and the symptoms produced by them are character¬ 
istic and easily differentiated clinically. The most common species 
is the tertian or Plasmodium falciparum , and this will first be de¬ 
scribed. 
EXPLANATION OF PLATE 4. 
Figure 1.— Plasmodium malaria. (Quartan plasmodium.) Young parasites. 
The so-called ring forms. Wright’s stain. X 1500. 
Figure 2.— Plasmodium malaria. Half-grown parasite. The so-called band 
form. Wright’s stain. X 1S00. 
Figure 3. — Plasmodium malaria. Three quarters-grown parasite. Wright’s 
stain. X 1500. 
Figure 4.— Plasmodium malaria'. Large band form. Wright’s stain. X 1800. 
EXPLANATION OF PLATE 5. 
Figure 1.— Plasmodium malaria. (Quartan plasmodium.) Pre-sporulating 
parasite. Wright’s stain. X 1500. 
Figure 2.— Plasmodium malaria. Sporulating parasite. Wright’s stain. X 1200. 
Figure 3. — Plasmodium malaria. Sporulating parasite. X 1200. 
Figure 4.— Plasmodium malaria. Young gamete. X 1800. 
Plasmodium falciparum appears first within or upon the infected 
red corpuscle as a round hyaline ring or disk. The infected cell is 
greenish in color, smaller than the normal corpuscles surrounding 
it, and generally crenated. These young “ring-forms" are irregular 
in outline, one portion of the ring being larger than the rest, giving 
it the so-called “signet-ring" appearance. The organism is quite 
actively ameboid and only rarely is there more than two parasites 
observed within one corpuscle. In the course of from 20 to 24 
hours the hyaline forms become pigmented, the pigment occurring 
in the form of fine, reddish-brown granules somewhat resembling 
those found in the tertian parasite. The pigment is in larger amount 
than in the quotidian plasmodium and is generally motile. As soon 
as pigmentation occurs the parasites collect in the internal organs, 
and it is therefore rare to find the half and fully grown forms of 
this plasmodium in the peripheral blood. 
As growth increases ameboid motion becomes lost and at the time 
of segmentation or sporulation, which occurs at the end of 48 hours 
