24 
PROPHYLAXIS OF MALARIA. 
motility was present at the time of fixation many irregular forms, of 
the “ring*’ are observed, due to minute pseudopodia arising from 
the periphery of the organism. Delicate, blue-stained filaments of 
cytoplasm may be observed spreading over the infected erythrocyte 
and the chromatin mass may be situated at any portion of the para¬ 
site, quite often within one of the pseudopodia. As the schizont 
becomes larger the blue-stained cytoplasm is observed to contain 
greenish pigment and the single dot of chromatin has increased 
until the cytoplasm contains threads and granules of this substance 
stained a brilliant red. At a certain period of development the 
chromatin divides into such fine filaments and grains that in the 
stained preparations the parasites at this stage appear to be almost 
devoid of this substance but prolonged staining will generally 
demonstrate a collection of very fine chromatin crannies inclosed 
within an unstained area, the vesicular portion of the nucleus. As 
sporulation approaches the cytoplasm stains more intensely blue 
and the chromatin becomes arranged in irregular clumps through¬ 
out the cytoplasm. The sporulating plasmodia present a cytoplasm 
filled with spherical or oval masses of red chromatin and careful 
examination will demonstrate that each chromatin mass is surround¬ 
ed by a blue-stained ring of the cytoplasm; the pigment is collected 
into one or more irregular masses within the organism along with 
some residual cytoplasm which stains a pale blue. Not infrequently 
free spores, or merozoites , are observed in stained preparations, and 
are composed of a ring-shaped or almost solid mass of blue-stained 
cytoplasm containing a small bright red dot of chromatin. 
Morphology of Plasmodium malarias (the quartan plasmodium ) 
(Schizogony or Human Cycle'). —This species of malaria plasmo¬ 
dium completes its development in man in 72 hours, producing that 
type of the disease characterized by a chill and a rise in temperature 
at the end of every third clay. With the exception of the quotidian 
form of estivo-autumnal infection, this is the most uncommon form 
of malaria. 
Like the tertian plasmodium, the organism causing quartan ma¬ 
larial infections appears at first, in the living specimen, as a small 
actively ameboid hyaline body within or upon the red blood cor¬ 
puscle. It will be noticed that ameboid motion is less marked than 
in the tertian parasite, and that the youngest forms are smaller than 
the youngest forms of the latter species. The quartan parasite rap¬ 
idly becomes pigmented, the pigment being dark brown in color, 
less motile than the pigment of the tertian plasmodium, and ar¬ 
ranged around the periphery of the organism. The outline of the 
parasite, at every stage of development, is much more distinct than 
is that of the tertian parasite, and the infected red corpuscle, instead 
